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5043 - Cumberland Trucks

1. ik raisi SECTION 3 Maintenance Spring brake chambers are an important part of the braking system While they do not require scheduled servicing it is good preventive maintenance to inspect the spring brake and service brake actuators externally to ensure they continue to perform within design specification MGM Brakes recommends the following routine inspections whenever the equipment is in the shop for regular servicing or at a minimum of every 50 000 miles It is important to note that virtually all spring brake chambers today have been mechanically sealed at the factory for your protection There are no user serviceable parts inside the spring brake chamber so you should never attempt to disassemble the unit for any reason The spring brake contains a large powerful spring with extreme force that could cause serious bodily injury if it were suddenly and inadvertently released If the spring brake has failed or been damaged remove either the entire actuator as described in Section 7 or the single piggyback as described in Section 5 and properly dispose of the unit as outlined in Section 10 Identifying An MGM Brakes Product All MGM brake actuators made after October 1987 have an aluminum identifi cation tag attached to the actuator that has the MGM Brakes part number date of manufacture and often a customer part number clearly stamped on it Refer to the adjacent illustration for the location of the I D tag
2. TECH SERVICE ai gt Serr studyj X Tra ini g Program Tu SA 11 7 Spring Brakes Table of Contents Introduction How to Use the Study Guide 2 3 e MGM Brakes Brief Company History 4 5 e SECTION 1 Foundation System 6 8 e SECTION 2 Spring Brakes and Service Chambers 9 11 e SECTION 3 Maintenance 12 18 e SECTION 4 Manually Releasing the Brake 19 21 e SECTION 5 Replacing the Single Piggyback Chamber 22 25 e SECTION 6 Removal and Replacement of the Service Diaphragm 26 28 e SECTION 7 Removing the Combination Tandem BifTaKe Ib 29 SECTION 8 Procedure to Cut the Universal Service Push Rod 30 31 e SECTION 9 Reinstalling the Combination Tandem Brake 32 35 e SECTION 10 Recommended Disposal Procedure 36 37 e SECTION 11 Brake Adifustment 38 41 e SECTION 12 3 Inch Long Stroke Brakes 42 44 Final Revlevv 46 61 e Mail In Quiz Form 63 VVARNING Installation maintenance and replacement of MGM Brakes
3. Then paying close attention to assure all mating surfaces are in alignment and that the air inlet ports are properly positioned to mate with the vehicle air supply lines install the new clamp band Install the new clamp band bolts and nuts and alternately tighten each nut in 5 to 10 Lbs Ft torque increments while constantly rechecking the alignment of the mating parts If re alignment of the mating parts is required loosen the clamp nuts and repeat the installation process To help seat the clamp band firmly tap around the circumference of the clamp band with a plastic or rubber hammer Fig 38 while alternately tightening Figure 38 the nuts to 30 35 Lbs Ft of torque Be sure to reinstall or replace any 1 D tags that may have been attached to the clamp band bolt such as the 3 inch trapezoid identification tag or the Heavy Duty identification tag Reinstall the air supply lines to the chamber making sure each line is mated to the correct air inlet port follow the identification marks made earlier Be sure to apply a non hardening sealing compound to the fittings and tighten them according to the manufacturer s recommended specifications MGM Brakes recommends that the fittings be tightened to 25 30 Lbs Ft of torque into the chamber air inlet ports Now using the vehicle s system air charge the parking brake with full line pressure minimum 100 psi and check for air leaks by applying soapy water or leak detec
4. OFF NOT APPLIED Angle must always be greater than 90 due to various slack adjuster lengths and installation setups Refer to axle or Original Equipment Manufacturer s manual for recommended angle Stroke should be as short as possible with no lining to drum contact To check brake adjustment apply 90 to 100 psi air pressure to the service chamber Consult the vehicle manufacturer for the correct angle between the slack adjuster arm and push rod and or the push rod length This is necessary since different dimensions are required for automatic or manual slacks various slack lengths and different slack adjuster manufacturers IMPROPERLY ADJUSTED BRAKES ON APPLIED oer 277 Maximum recommended readjustment ge stroke has been exceeded p See Recommended Readjustment Stroke chart on next page Fig 75 Figure 74 Recommended Readjustment Stroke APPROX RATED MAXIMUM B MV MA TYPE EFFECTIVE DIAPHRAGM STROKE OF STROKE WITH RECOMMENDED O D CHAMBER BRAKES READJUSTMENT ADJUSTED STROKE oo L 9 500 125 1 75 45 12 12 550 140 175 45 SHOULD 16 16 600 150 225 57 BEAS 16 16 600 150 250 64 SHORT AS 20 20 650 165 225 57 POSSIBLE 20L 20 650 165 250 64 WITHOUT 24 24 700 175 225 57 DINING TO 21 24 700 175 250 64 ap 24 700 175 300 76 CONTACT 50 30 1866 200125060 64 SRARES 30LP3 350 18 00 2000
5. True False lf leaks are detected around the circumference of the clamp band tighten the clamp band bolts until the leaks cease True False When storing the release bolt in the storage pocket on the brake tighten the release bolt nut against the flat washer to 10 Lbs Ft of torque True False To uncage a spring brake with an integral release bolt use an impact wrench and turn the bolt until it is fully engaged into the unit and the slotted nut bottoms out True False Sections 7 amp 8 51 52 53 54 55 Before you begin to remove the combination tandem brake from the vehicle A manually release the brake B determine the manufacturer of the brake C visually inspect the brake for any damage D None of the above E Allthe above The X dimension is measured from A the bottom of the actuator to the end of the piston rod B the bottom ot the actuator to the center of the yoke pin C the bottom of the actuator to the end of the yoke D the end of the rod to the end of the threads E None ofthe above Before marking the push rod to be cut on the new unit A remove the release bolt and place it in the storage pocket B remove the jam nut from the push rod C make sure the push rod is fully retracted to the zero 0 stroke position D insert the dust cap into the release bolt hole and snap tightly into place E Allthe above Failure to fully cage release the spring brake to zero 0 st
6. angled away from each other angled in toward each other parallel to each other touching each other All the above m om p 25 Placing the split or hardened steel flat washers between the brake chamber and the bracket will A allow the chamber to flex resulting in premature failure of the N P chamber B allow the installer to apply an additional 25 Lbs Ft of torque to the nuts C provide additional support to the N P chamber D reduce the possibility of corrosion between the bracket and N P chamber E B amp C 26 MGM Brakes recommends routine inspection of the brake chambers whenever the equipment is in the shop or ata minimum of every 75 000 miles True False 27 To reduce the possibility of serious injury when removing an uncaged actuator use a vise grip to relieve the pressure being applied to the slack adjuster True False 28 f the vent holes in the head of the brake become restricted with dirt or concrete they can be reamed out using a power drill witha 3 8 inch drill bit True False 29 When installing an MGM Brakes spring brake equipped with an external breather tube the tube must be positioned in the upper quadrant 9 00 to 3 00 o clock away from the road surface True False 30 Any hose with damage extending through the outer reinforcement ply or with a bulge or swelling when air pressure is applied will cause the vehicle to be placed Out of Service by an inspecting officer True Fal
7. A WARNING DO NOT use a power drill as you may damage the diaphragm or other internal parts Carefully inspect all air lines hoses and fittings attached to the chamber Fig 19 Remove and replace any damaged or leaking parts Remember never disconnect any air hose or air line that contains air pressure as it may whip as the air escapes Never remove a component or pipe plug unless you re absolutely sure that all system pressure has been depleted Be careful to never exceed recommended air pressures Always wear safety glasses while working with pressurized air and never look directly into air jets or direct them at anyone NOTE North American Uniform Out of Service Criteria identifies the following items relating to air lines hoses and fittings as cause to place any commercial vehicle Out of Service 1 Any hose with damage extending through the outer reinforcement ply Rubber impregnated fabric cover is not a reinforcement ply Thermoplastic nylon may have braid reinforcement or color difference between cover and inner tube Any exposure of the second color is an out of service condition 2 Any hose with a bulge or swelling when air L within pressure is applied m 2 3 Any hose or tubing with an audible air leak AP 6 anyvvhere other than at a proper connection sil ka 4 Two hoses improperly joined such as a splice made by sliding the hose ends over a piece of tubing and clamping the
8. 1 2 brake toward the 20 out of service rule while any brake 1 4 inch or more beyond the readjustment limit will count as one 1 defective brake Example BRAKE ADJUSTMENT PASSENGER SSIDE 1 1 2 1 1 2 iz ua E AXLE 1 2 3 4 5 STEER AXLE DRIVE AXLE DRIVE AXLE TRAILER AXLE TRAILER AXLE DRIVER S SIDE 1 1 2 1 3 4 2 1 8 2 1 8 2 1 4 Ss GHAN CLAMP TYPE CHAMBERS Figure 73 In this example Fig 73 the brakes on Axles 1 and 2 are within the recommended readjustment limit The brakes on the driver s side of Axles 3 and 4 are 1 8th of an inch over the recommended readjustment limit for a type 30 chamber Each will count as 1 2 brake toward the 20 rule for a total of one 1 full brake The brake on the driver s side of Axle 5 is 1 4 inch beyond the recommended readjustment limit and counts as one 1 full brake Therefore the total number of defective brakes totals two 2 on this five 5 axle vehicle placing the vehicle out of service under the 20 rule NOTE A brake found at the adjustment limit is not in violation See Cam Brake Adjustment Chart below Fig 74 for important information CAM BRAKE ADJUSTMENT ALL MODELS SPRING BRAKE AND SERVICE BRAKE ACTUATORS NOTE The last half of an air chamber stroke is less efficient than the first half Therefore the following adjustments are recommended for maximum efficiency when using manually adjusted slack adjusters BRAKES
9. 27 Incidentally the unscrewing and or removal of the release bolt from MG T models does not actually cage the power spring as it does on MJ ET units This operation only removes the power spring force from the slack adjuster To reinstall and or retighten the release bolt in all piston type models apply line pressure to the spring brake and screw the release bolt completely into the chamber and tighten to 35 45 Lbs Ft of torque Fig 32 Miia T Figure 32 To make the manual release procedure easier on double diaphragm brakes you can apply 90 100 psi air pressure to the inlet port marked SPRING BRAKE prior to inserting the RELEASE BOLT but be sure to exhaust all air pressure after establishing the proper amount of thread extends above the RELEASE NUT To release the brake reverse the order of operation After the brake has been released re install the RELEASE BOL I FLAT WASHER and RELEASE NUT into the storage pocket on the side of the brake MGM Brakes recommends applying 10 Lbs Ft of torque to the nut against the flat washer SECTION 5 Replacing the Single Piggyback Chamber To begin with make sure the wheels of the vehicle have been securely chocked or blocked to prevent the vehicle from moving Now manually or with system air pressure extend the service push rod slightly and clamp it in place with vise grip pliers to prevent sudden separation of the single piggyback from the service chamber
10. Tighten the RELEASE NUT against the flat WASHER to 10 Lbs Ft torque If the spring brake chamber is equipped with an integral release bolt Fig 29 use a 15 16 inch wrench DO NOT USE AN IMPACT WRENCH and simply turn the release bolt clockwise until the bolt 7 p LE 8 is fully engaged into the unit and the slotted nut bottoms out Tighten the Figure 42 nut to 45 50 Lbs Ft of torque SECTION 6 Removal and Replacement of the Service Diaphragm Often when a leak is detected in the service side of the spring brake service brake chamber the problem can be corrected by simply replacing the SERVICE DIAPHRAGM Fig 43 To begin with make sure the wheels of the vehicle have been securely chocked or blocked to prevent the vehicle Figure 43 from moving Now manually or with system air pressure extend the service push rod slightly and clamp it in place with vise grip pliers to prevent sudden separation of the single piggyback from the service chamber when the clamp band is removed Fig 44 Be sure to cage the single piggyback spring brake before removal following the procedures outlined in Section 4 of this booklet or in Section 2 of the MGM Brakes TR Service Manual Form 5011 Figure 44 NOTE In many cases it may not be necessary to disconnect the air lines from the spring brake during the diaphragm replacement procedure as long as correct and straight part
11. Type 30 chambers from 2 00 inches to A 2 25inches B 2 50 inches C 2 75inches D 3 00 inches E Noneofthe above 90 All Long Stroke chambers are identified by A permanent markings B square inlet ports C redtriangular tags D trapezoidal D tags E A B amp D 91 Increase in chamber stroke caused by improper brake adjustment has little or no effect on the distance required to stop the vehicle True False 92 Elevated brake temperatures are a major factor in the loss of braking effectiveness True False 93 The performance of 2 50 inch standard stroke brakes that are technically in adjustment suffer little or no loss in braking performance when drum temperatures are raised to a realistic operating temperature of 600 F True False Notes MAIL IN QUIZ FORM Name Section 1 1 9 10 ALI BO CO DU EL AU BUCO DU EU ALI BL CL DU EU ALI BL CO DU EU ALI BO CO DU EU TO FO TO FO TO FO TO FO TO FO Section 2 11 12 13 14 15 16 17 18 19 20 ALI BL CL DU EU ALI BL CL DU EU ALI BO CO DU EU ALI BL CL DU EU ALI BL CL DU EL TO FO TO FO TO FO TO FO TO FO Section 3 21 22 23 24 25 26 27 28 29 30 ALI BO CO DU EL ALI BU CO DU EU ALI BL CO DU EU ALI BO CO DU EU ALI BL CL DU EL TO FO TO FO TO FO TO FO TO FO Company Street City Section 4 31 32 33 34 35 36 37 38 39 40 Se
12. and slack adjuster True False 17 A spring brake has two chambers service brake chamber and parking brake chamber True False 18 The parking emergency brake chamber contains a large powerful spring True False 19 Double diaphragm brakes are the only types of spring brake used on trucks buses trailers and other heavy duty commercial vehicles today True False 20 To park the vehicle air is applied to the parking brake through a valve mounted on the vehicle s dash True False Section 3 21 Before proceeding with the recommended inspection procedure be sure to A totally deplete the air system and manually release the brakes B tum off the engine and chock or block the wheels C manually release the brakes and engage the transmission turnoff the engine and manually release the brakes E None ofthe above 22 ACVSA inspector will if any non manufactured holes or cracks have been detected in the spring brake housing section of the parking brake A ask you to adjust the brakes B place the vehicle Out of Service C provide areplacement brake D allowthe vehicle to continue operation E None ofthe above 23 On an MGM Brakes spring brake eguipped with an external breather tube the end of the breather tube should be inserted a minimum of into each elbow A 1 8 inch B 1 4 inch C 1 2 inch 3 4 inch E None of the above 24 When properly torgued the clamp band ears should be
13. been designed to allow you to work at your own pace regardless of your schedule to become better acquainted with the maintenance and safety procedures relating to the repair replacement inspection and preventive maintenance of service chambers and spring brakes in general and MGM Brakes products in particular How To Use The Study Guide Begin by carefully reading the text portion of each chapter Feel free to make notes underline or highlight if you wish This can help you remember what you have read At the end of this booklet you will find a final review quiz This is your final test Be sure to answer each question to the best of your ability The questions contained in the quiz are straightforward multiple choice or true and false and there are no trick questions If you are unsure about your answer to a particular question review the appropriate chapter The correct answer to the question is contained in the text of the chapter Study at your own pace There is no time limit on completing this program MGM Brakes will issue a Certificate of Completion and a patch to each participant scoring a minimum of 85 Information on how to obtain your Certificate and patch is provided at the end of this booklet MGM Brakes Brief Company History MGM Brakes was established in 1957 when John Miller Swen Gummer and Joseph Meyers developed and marketed the very first MGM Brake Gummer owner of a sawmill and a logger him
14. chambers reguire a high degree of skill and experience Improper installation maintenance or replacement can result in brake failure and resulting loss of control of the vehicle and possible injury or death MGM Brakes a division of Indian Head Industries Inc IHI does not authorize anyone other than highly skilled and experienced persons to attempt to utilize the instructions contained in this booklet Although every precaution has been taken in the preparation of this booklet MGM Brakes assumes no responsibility for errors or omissions Neither is any liability assumed for damages resulting from or claimed to be the result of the use of the information contained herein Information subject to change without notice MGM Brakes and IHI shall have no liability of any kind for damages arising out of any other use of the information contained within this booklet Copyright 2000 MGM Brakes All rights reserved Printed in U S A No part of this booklet shall be reproduced stored in a retrieval system or transmitted by any means electronic mechanical photocopying recording or otherwise without written permission from MGM Brakes Self Study Training Program Introduction Welcome to MGM Brake s BrakeTECH SERVICE Self Study Training Program MGM Brakes created this program for maintenance personnel involved in maintaining and repairing the service and spring brake chambers on commercial vehicles and heavy equipment This booklet has
15. disc brakes utilize a slack adjuster to transfer force True False Wedge brakes utilize a bushing and roller assembly to spread the brake shoes and force the lining against the drum True False Disc brakes consist of a rotor hub wheel and caliper True False The caliper is an assembly that positions the brake pads relative to the rotor True False Section 2 11 12 13 The functions independently of the spring brake chamber master brake service brake slave brake wedge brake A amp C mU uz Spring brakes function as A service brakes B emergency brakes C parking brakes D Allthe above E None ofthe above The performs the normal slowing and stopping function A treadle valve B service brake C spring brake D relay valve E None ofthe above 14 The parking emergency brake contains a diaphragm piston amp lock ring diaphragm piston amp o rings diaphragm or piston amp large powerful spring diaphragm piston amp drive nut None of the above mTUO uz 15 are the two main types of spring brakes commonly used on trucks buses trailers and other types of heavy duty commercial vehicles throughout the world Double diaphragm amp piston diaphragm Air over hydraulic and double diaphragm Piston diaphragm amp roto lock Double diaphragm amp single roll diaphragm None of the above mTU uz 16 The service push rod is connected to the foundation brake via a yoke
16. hold the single piggyback in place Now using a plastic or rubber mallet tap the clamp band around its circumference while alternately tightening the clamp band nuts in 5 10 Lbs Ft torque increments Fig 49 Constantly checking the alignment of the mating parts Figure 48 during this operation will ensure proper seating MGM Brakes recommends tightening the clamp band nuts to 30 35 Lbs Ft of torque Be sure to reinstall or replace any I D tags that may have been attached to the clamp band bolt such as the 3 inch trapezoid identification tag or the Heavy Duty identification tag Figure 49 Now you can apply air pressure to the service chamber and using soapy water NEVER USE ANY TYPE OF OIL or leak detection solution check for air leaks If leaks are detected repeat the clamp band installation procedure When you are satisfied that there are no leaks remove the vise grip pliers from the service chamber push rod SECTION 7 Removing the Combination Tandem Brake Before you start to remove the combination tandem brake trom the vehicle be sure to inspect the brake for any damage following the procedure in Section 1 of this booklet or Section 3 of the MGM Brakes TR Service Manual Form 5011 Once you are sure the brake has not been damaged and can be safely handled determine the manufacturer of the combination tandem chamber you will be removing from the vehicle and manually release the spr
17. hose to the tube 5 Any air hose or tubing that is damaged by heat or that is cracked broken or crimped in such a manner as to restrict airflow Figure 20 Inspect the PUSH ROD Fig 20 to be sure it is working freely that it is not bent or binding and is square to the chamber bottom within 3 in any direction and at any point during the stroke of the chamber If the PUSH ROD is not Square make corrections by repositioning the chamber on the mounting bracket or by shimming the slack adjuster to the right or left of the camshaft as required Figure 21 On units equipped with a DUST BOOT Fig 21 check the BOOT for damage and replace as necessary Inspect the YOKE ASSEMBLY Fig 22 Make sure the YOKE PIN is installed and locked into place with a COTTER PIN Replace any damaged worn or missing parts MGM Brakes recommends that the YOKE JAM NUT be tightened to 25 35 Lbs Ft of torque Figure 22 Figure 23 J And finally before you come out from under the vehicle visually inspect the foundation brake Fig 23 to make sure there are no loose missing or broken mechanical components Many commercial vehicles are placed out of service by Commercial Vehicle Safety Alliance CVSA inspectors for the following highly visible problems 1 Absence of effective braking action when air is applied to the service brakes i e brake linings failing to move or contact the drum 2 Missing or b
18. most commonly used foundation brake on heavy duty commercial vehicles today Fig 2 L a i br i R t ni J 7 NK 8 b m 2 i d E Figure 2 Cam brakes operate through the action of the brake chamber which is attached to a bracket mounted to the foundation brake The brake chamber operates on compressed air supplied through the service port to the top of the service diaphragm When compressed air enters the service chamber the service diaphragm is forced downward against the service piston The service piston is linked to the foundation brake by the piston push rod which is connected to a manual or automatic slack adjuster by a yoke The slack adjuster is attached to the camshaft and when the push rod is forced outward the slack adjuster transforms the movement which is linear force into a twisting or rotating force or torque The torque applied to the end of the camshaft causes the S cam on the other end to rotate spreading the brake shoes This forces the brake linings out against the drum slowing the vehicle Wedge Brakes While cam brakes rely on the slack adjuster to transfer linear force into torque to apply the brakes wedge brakes operate entirely ona different principle Fig 3 Figure 3 Wedge brakes utilize a wedge and roller assembly to spread the brake shoes and force the lining against the drum The angle of the wedge and the size of the brake chambe
19. on the various models manu factured by MGM Brakes Fig 9 Figure 9 MGM Brakes actuators are assigned a seven 7 digit part number that begins with a 1 2 3 4 or 5 depending on the Model Date codes simply show the month day and year MMDDYY and are prefixed by the letter C for Cloverdale CA and M for Murphy NC which identifies the plant where the actuator was manufactured Example M102999 e Letter prefix identifies the manufacturing plant e First two digits identify the month of manufacture e Second two digits identify the day of manufacture Final two digits identify the year of manufacture Therefore the brake in this example would have been manufactured in Murphy North Carolina on October 29th 1999 Externally the MGM Brakes logo can be found on all die cast aluminum cylinder cases and center sections and on most stamped steel heads pressure caps and non pressure chambers The MGM Brakes logo can also be found on the clamp bands and the plastic end cap Internally the MGM Brakes logo can be found stamped on the mounting bolt heads and piston plates and embossed on the diaphragms External Inspection Points and Procedures Before proceeding with the recommended inspection points there are a few common sense precautions that should be taken First be sure you turn off the engine before working under any vehicle and always chock or block the wheels Depleting the air system pressur
20. proper clothing C proper eye protection D Allthe above E None of the above 74 To make sure the coils of the power spring have been completely cut you should A remove the chamber from the container and shake it B use your finger to see if the coils of the power spring are loose remove the release bolt to see if the brake still vvorks use a screwdriver to check that the coils are loose All the above mM O 75 The proper disposal of old spring brake chambers is a major concern throughout the industry True False 76 Spring brake actuators should be safely disarmed to prevent serious personal injury from the sudden accidental release of the high energy power spring True False 77 Wearing protective clothing and eye protection are an option when operating an acetylene gas torch True False 78 Cutting through the first coil of the power spring may produce a low pitched popping sound and cause the brake to jump inside the container True False Section 11 79 During roadside inspections the single most cited reason for a commercial vehicle to be placed Out of Service Is A oil soaked brakes B bent or crimped air lines C audible air leaks D out or adjustment brakes E mismatch of chamber size 80 A fully loaded truck trailer traveling at 40 MPH under the best of road conditions will require approximately feet of stopping distance A 342 B 298 C 260 D 189 E None of the above 81 ACommerc
21. that unit Otherwise since dimensions vary between automatic and manual slack adjusters slack lengths and different manufacturers it will be necessary to refer to the vehicle manufacturer s recommendation for the correct angle between the slack adjuster arm and push rod and or the push rod length Failure to fully cage release the failed unit to zero 0 stroke before taking either the X or Y dimension measurement will result in the push rod on the new unit being cut to an operational length longer than required The additional length will be equal to the distance remaining within the old chamber needed to achieve zero 0 stroke The extra rod length will have a negative effect on the life of the brake Causing among other things premature failure of the center section seal and excessive contact between the push rod and the push rod hole in the non pressure housing In some cases the additional push rod length has contributed to the cracking and eventual failure of the non pressure housing at the mounting studs or even the failure of the mounting bracket Before marking the push rod to be cut on the new unit be sure the spring chamber and push rod are fully retracted to the zero 0 stroke position This may be done with the release or caging bolt or by applying 90 100 psi air pressure to the spring chamber air inlet port Then take the measured X dimension from the removed unit and mark the push rod of the new
22. well done will go one step further toward singling you out in the eyes of your colleagues and customers as a true expert on MGM Brakes products and the service procedures associated with them Participants failing to score the required 85 will be sent a letter of encouragement along with another booklet MGM Brakes will allow such a participant to make a second effort to succeed with the BrakeTECH SERVICE Self Study Training Program Quiz Questions Section 1 1 The actual braking function is performed by the A brake drum B foundation brake C spring brake D brake shoes E slack adjuster 2 foundation brake consists of the A brake drum spider brake shoes amp linings B camshafis return springs anchor pins amp rollers C brake chamber slack adjuster air lines amp fittings D A amp B E Noneofthe above 3 The converts air pressure into mechanical pressure A return springs B slack adjuster C brake shoes D brake chamber E None ofthe above 4 There are types of air operated foundation brakes used on medium and heavy duty trucks two three four five SIX TU WO gt 5 Thethree types of air operated foundation brakes are vacuum hydraulic amp cam hydraulic wedge amp cam cam wedge amp disc cam wedge amp vacuum All the above A B C D 6 The slack adjuster converts air pressure into mechanical pressure True False 10 Like cam brakes
23. with the American Trucking Association the National Highway Traffic Safety Administration NHTSA and other industry leaders have worked very closely with CVSA on the Long Stroke concept Because of the performance benefits CVSA has increased the Out of Adjustment criteria for 3 inch Long Stroke brakes to 2 5 inches compared to 2 inches for standard 2 5 inch stroke chambers Due to this additional allowance in stroke it is extremely important that you know how to identify Long Stroke chambers Identification All Long Stroke chambers are identifiable by square ports trapezoidal I D tags and permanent markings Fig 77 Long Stroke Spring Brake Identification SERVICING INSTRUCTIONS ARE STANDARDIZED TRAPEZOIDAL EMBOSSED INTO THE FLANGE SHAPED TAG SECURED DASE POR AH TOSERVICE sing I REQUIRED m CLAMP BAND BOLT 1 WITH FAL HLIT SOUARE PORTE ARE CAST FIGHT ATG FLASIE CASE TO Lie aoe THAT G CC asd EASILY ETEL TABLE Figure 77 NOTE IMPORTANT When servicing a truck trailer equipped with 3 Inch Long Stroke actuators it is crucial that you replace like for like and do not install a standard stroke actuator in place of a Long Stroke actuator Installing a standard stroke 2 5 inch chamber in place of a Long Stroke 38 inch chamber can produce an imbalance in the stoppi
24. 04 547 9367 fax e mail mail mgqmbrakes com WWW mgmbrakes com 2000 MGM Brakes All Rights Reserved Printed in U S A
25. 300 DRAGGING 35 36 900 230 300 6 SOURCE MVMA Motor Vehicle Manufacturers Association Note The push rod must remain perpendicular to the bottom surface of the non pressure chamber NPC within 3 zero to full stroke Figure 75 SECTION 12 3 Inch Long Stroke Brakes Elevated brake temperatures are a major factor in the loss of braking effectiveness We have seen how stopping distances were adversely affected by the increase in stroke caused by improper brake adjustment Now consider the increase in stroke brought on by the heat induced expansion of the brake drum If the temperature of the drums on the same test vehicle were raised to a realistic operating temperature of 600 F the stopping distance would increase to approximately 692 feet even though the brakes were adjusted to the CVSA limit You can see that even though the brakes were technically in adjustment the influence of heat on the chamber stroke in conjunction with normal brake lining fade more than doubled the stopping distance That is why 3 inch Long Stroke brakes Fig 76 Figure 76 have become one of the hottest topics in the trucking industry today The bottom line for the use of Long Stroke brakes is safety Even with proper maintenance and the incorporation of automatic slack adjusters vehicles equipped with standard 2 5 inch stroke chambers can still suffer a loss in braking performance That is why MGM Brakes along
26. MUST replace with a 3 inch Long Stroke diaphragm Using the incorrect diaphragm will change the performance characteristics of the actuator adversely effecting its operating efficiency which could result in catastrophic failure of the actuator Notes Final Review Congratulations You have completed the MGM Brakes BrakeTECH SERVICE Self Study Training Program and now you are ready to test your knowledge about the maintenance and repair of brake actuators To begin remove the perforated Mail In Quiz Form answer sheet from the back of the booklet Next read the quiz questions on pages 47 61 circling your choice for the best answer for each question Finally use a black or blue ink pen and completely darken the box on the Mail In Quiz Form which corresponds to each question This will allow us to more efficiently process your quiz Make sure you answer each and every question unanswered questions will be graded as incorrect When you have finished fold your answer sheet as indicated and tape or staple it closed no envelope is required Attach the proper postage and send your Mail In Quiz Form back to MGM Brakes Please allow at least four weeks for grading Participants scoring 85 or better will have successfully completed the BrakeTECH SERVICE Self Study Training Program and will receive a Certificate of Completion from MGM Brakes along with a BrakeTECH SERVICE patch These tokens of our appreciation for a job
27. Next through one of the openings in the side of the container use an acetylene gas torch to cut a hole 1 1 2 to 2 inches in diameter in the head of the brake to expose the power spring At this point DO NOT Information concerning where to obtain a suitable container is available from your MGM Brakes representative cut the power spring Repeat the process through the opening on the opposite side of the container Cutting two holes opposite each other provides the torch with sufficient oxygen for the cutting of the power spring Now use the torch to completely cut through one of the coils of the exposed power spring Cutting the first coil may produce a low pitched pop or may cause the brake to jump in the box Repeat the process through the opening on the opposite side of the container A WARNING DO NOT cut the clamp band bolts before cutting the power spring coils To make sure you have completely cut the power spring coils use a screwdriver or similar tool to check that the coils are loose inside the head of the brake DO NOT PLACE YOUR HANDS OR FINGERS INSIDE THE CONTAINER If the coils can be moved the brake has been rendered harmless and can be discarded MGM Brakes does not rebuild nor condone the use of rebuilt air brake actuators This is because they are very important safety devices that actuate foundation brakes and perform vital parking and emergency brake functions Because they operate in the worst possible e
28. are ready to proceed with the inspection of the brake The first thing you want to inspect is the plastic END CAP or DUST PLUG Fig 11a Make sure it is not damaged and that it is snapped tightly in place and if it is designed to be attached to the head it is securely attached While these caps plugs require no special positioning or maintenance they must be snapped tightly into the release bolt access hole to prevent ingestion of large particles of contamination such grit d and gravel Failure to properly install the cap plug can adversely effect the warranty on some models of spring brakes such as Figure 12 MGM Brakes models equipped with the external breather tube The END CAP on MGM Brakes TR T and TR TS model brakes are equipped with a rubber O ring Fig 12 to help seal out moisture Ensure the O ring is free of damage and is properly positioned on the END CAP A WARNING Operating units equipped with the EXTERNAL BREATHER TUBE without the END CAP and O RING securely in place will void the MGM Brakes Warranty without remedy Next inspect the exterior surfaces of the spring brake for signs of damage or excessive corrosion If any of these conditions are seen or suspected carefully remove the combination tandem brake by following the manufacturer s recommended procedure For MGM Brakes see Section 7 of this booklet or refer to Section 3 of the MGM Brakes TR Service Manual Form 5011 Be
29. ctions 5 amp 6 41 42 43 44 45 46 47 48 49 50 Sections 7 amp 8 51 52 53 54 55 56 57 58 59 60 ALI BO CL DU EU ALI BO CL DU EU ALI BO CL DU EL ALI BO CL DU EL ALI BO CO DU EL TO FO TO FO TO FO TO FO TO FO ALI BO CO DU EU ALI BO CL DU EL ALI BO CL DU EL ALI BO CL DU EU AU BU CO DU EU TO FO TO FO TO FO TO FO TO FO ALI BO CO DU EU ALI BU CL DU EU ALI BO CL DU EU ALI BO CL DU EL ALI BL CO DO TO FO TO FO TO FO TO FO TO FL State Zip Date Section 9 61 62 63 64 65 66 67 68 69 70 Section 10 71 72 73 74 75 76 77 78 Section 11 79 80 81 82 83 84 85 86 87 88 ALI BL CL DL EL ALI BOCODU EU ALI BOCODU EU AU BOCODU EU AU BOCODU EU TO FO TO FO TOFO TO FO TOFU ALI BOCO DU EU AU BOCODU EU AU BOCODU EU ALI BOCODU EU TOFO TOFO TOFO TO FO AU BO CL DU EU ALI BOCO DUO EU ALI BL CL DL EU ALI BL CL DL EL ALI BL CO DO EU TOFO TOFU TO FO TOFO TOFU Section 12 89 90 91 92 93 ALI BL CO DO EU ALI BL CL DO EL TLIFL TOFO TOFO fold here first PLACE STAMP HERE SERVICE Brake TECH MGM Brakes 8530 Cliff Cameron Drive Charlotte NC 28269 Attn Administration tape or staple here Form 5043 Revised 04103 MGM MeM Brakes 8530 Cliff Cameron Drive Charlotte NC 28269 800 527 1534 704 547 7411 7
30. e The proper disposal of old spring brake chambers is a concern of every fleet maintenance department and repair shop throughout the industry All retired spring brake actuators must be safely disarmed before they are disposed of to prevent serious personal injury from accidental sudden release of the high energy spring as much as 2700 165 of force in the parking chamber MGM Brakes has always recommended that the coils of the power spring be cut with an acetylene gas torch prior to disposal as outlined in MGM Brakes Technical Bulletin 031 This simple procedure renders the power spring inoperable permitting the chamber to be safely discarded Place the single piggyback or combination tandem unit in a properly constructed steel container Fig 70 The container must have openings to expose the head where it is to be cut with an acetylene gas torch It must also be strong enough to prevent parts from hurtling out should the unit suddenly separate before it is safely disarmed NOTE It is the user s responsibility to ensure the steel container is safe Position the chamber so the head can easily be accessed through the holes in the container Depending Figure 70 on the size of the container it may be necessary to cut the service push rod in order to fit a combination tandem spring brake into the container disarming box A WARNING Never operate an acetylene gas torch without wearing proper clothing and eye protection
31. e 58 recommended 133 155 Lbs Ft of torque Fig 59 NOTE If repositioning of the air inlet ports is required to assure proper mating and alignment with vehicle air lines with the inlet ports follow the procedure outlined in Section 5 of this booklet or in Section 4 of the MGM Brakes TR Service Manual Form 5011 The air lines should line up directly with the inlet ports and there should be no sharp bends or kinks in the air lines DO NOT use a 90 elbow fitting as this may restrict air flow and affect the performance of the unit Figure 59 NOTE IMPORTANT When installing any MGM Brakes model with the breather tube it is mandatory to position the breather tube so that it faces away from the road surface Fig 60 Failure to comply will void the MGM Brakes Warranty without remedy on these models Now you can reconnect the yoke to the slack adjuster being sure that the correct diameter and length of yoke pin is installed into the correct hole in the slack adjuster Be sure to secure the yoke pin with a new cotter pin Fig 61 Inspect the push rod to be sure that it is working free not bent or binding and is square to the chamber bottom within 3 in any direction at any point in the chamber stroke Fig 62 If the push rod is not square make corrections by repositioning the chamber on the mounting bracket and Figure 63 or by shimming the slack adjuster to the right or left on t
32. e may allow the vehicle to roll Also remember to keep your hands away from the actuator push rods and slack adjusters as they may apply as system pressure decreases Now before you begin working on or around the spring brake chamber or the foundation system take a few minutes to visually inspect the chamber to make sure it hasn t been damaged Fig 10 Brake chambers are positioned under the vehicle close to the road so they tend to take a lot of punishment If you suspect the brake has sustained structural damage for example the head is severely dented DO NOT attempt to cage the brake To reduce the possibility of serious injury when removing an Figure 10 uncaged actuator use an acetylene gas torch to cut the service push rod to relieve the pressure being applied to the slack adjuster After the push rod is cut carefully remove the unit from the vehicle and disarm the spring brake by following the recommended disarming procedure as described in Section 10 of this booklet NOTE Commercial Vehicle Safety Alliance CVSA inspectors will place a vehicle out of service if any non manufactured holes or cracks in the spring brake housing section of a parking brake are detected so be sure to thoroughly inspect the brake Also still on the subject of safe handling procedures NEVER strike any part of a spring brake with a hammer or other heavy object and NEVER drop a spring brake as structural damage may result Now you
33. epeat this step until you are sure of positive engagement Now using a 3 4 inch 15 16 inch for type 3036 and 3636 Models wrench DO NOT USE AN IMPACT TYPE WRENCH turn the RELEASE BOLT NUT clockwise until the RELEASE BOLT thread extends above the nut Fig 28 indicating that the brake is at zero 0 stroke Refer to the manufacturer s specifications for proper measurement NOTE For MGM Brakes TR TR T and TR TS models use the following information as a guideline Type 2430 amp 3030 Models 3 25 inches of thread above the nut Type 3036 amp 3636 Models 4 00 inches of thread above the nut NOTE It is essential that the brake being serviced be fully released to zero 0 stroke to assure that any measurements taken concerning rod length be correct should the decision be made to replace the complete i unit Improperly measuring the push rod length X amp Y dimensions on the old rod may result in the push rod on the replacement unit being cut to an incorrect length This may result in premature failure of the center seal on the replacement unit For example If the brake being serviced was a type 3030 model and the technician caged the brake so that only 2 50 inches Figure 29 of the release bolt thread protruded above the release bolt nut there would be approximately 3 4 inch of stroke remaining in the brake Therefore if the rod measurement of the brake being serviced were transferred to the rep
34. eption Time 75 Seconds Average Driver Reaction Time 75 Seconds Total Driver Perception And Reaction Time Distance Traveled In 1 5 Seconds Average Brake Lag Distance Time For Air To Pass Through a System in Good Working Order Distance Traveled In 27 Seconds Effective Braking Distance Feet Traveled After Brakes Make Contact With Drums With Good Braking Efficiency On Good Dry Pavement the Coefficient of Friction 8 Deceleration Rate 19 3 Feet Per Sec Average e Distances Based Upon a Fully Loaded Tractor Trailer NOTE These are the best possible stopping distances Under average conditions these distances will increase considerably Under the same test conditions at 60 MPH except that the brakes were adjusted to the CVSA accepted readjustment limit the stopping distance increased to 458 feet Considering that the brakes may be well out of adjustment the potential for disaster suddenly becomes all too real Currently CVSA inspectors will immediately place a truck trailer combo Out of Service if the number of defective out of adjustment brakes is equal to or greater than 20 percent of the brakes on the vehicle or combination truck and trailer combined Fig 72 Any defective out of adjustment brake that is less than 1 4 inch beyond OUT OF SERVICE 20 GUIDE EBS ES NUMBER OF BRAKES OF AXLES oF BRakes 20 REQUIRED FOR SE SERVICE Figure 72 the readjustment limit will count as
35. ess there is a severe air leak this should cage the brake allowing insertion of the release tool into the piston Install the flat washer and nut and tighten the nut finger tight Be sure to exhaust all air pressure once the brake has been manually caged Figure 50 Figure 52 SECTION 8 Procedure to Cut the Universal Service Push Rod Carefully and accurately measure and record the X and Y dimensions The X Dimension is measured from bottom of actuator to end of piston rod while the Y Dimension is measured from bottom of actuator to centerline of yoke pin Fig 52 NOTE If for some reason the release tool cannot be properly inserted into the piston and the brake cannot be caged either manually or with air pressure then the X and Y dimensions will need to be obtained from another like chamber on the same vehicle However it is important to verify that the chamber selected is an original equipment installation or if a replacement chamber that the push rod has been cut to the proper length If the vehicle is equipped with automatic slack adjusters this can be established by using the slack adjuster set up template to verify the correct angle between the slack adjuster arm and the push rod Be sure the chamber being used has been fully retracted to its zero 0 stroke position before taking any measurements Then the X and Y dimensions can be taken from
36. ference with a plastic or rubber mallet while A applying pressure to the clamp band ears with vise grip pliers B using your free hand to gently rock the piggyback from side to side C alternately tightening the nuts to 35 40 Lbs Ft of torque D turning the release bolt nut in a counter clockwise direction E None of the above 43 To detect air leaks around the clamp band and air fittings hold the brake under water to see if bubbles appear apply soapy water or leak detection solution apply soapy water or a light mineral oil listen for air escaping from the clamp band and fitting areas None of the above moO W gt 44 45 46 47 48 49 50 When reinstalling the external breather tube be sure to insert the end of the tube into the rubber elbow extending from the non pressure housing A 1 4 inch B 1 2 inch C 3 4 inch 1 inch E as far as possible Before installing a new diaphragm you should for damage or wear visually inspect the return spring visually inspect the piston plate visually inspect the non pressure chamber visually inspect the flange case All the above m uc un When installing new clamp band bolts and nuts it is best to completely tighten one of the nuts before tightening the other True False When reinstalling the air supply lines apply a non hardening sealing compound to the fittings and tighten them to 25 30 Lbs Ft of torque into the chamber air inlet ports
37. g the new combination tandem brake you should take a few minutes to apply a protective coating of grease to the bracket surface apply a coat of epoxy paint to the bracket surface remove any burrs or debris ensure the bracket surface is free of cracks C amp D mU O Ww gt 62 After the brake has been installed on the bracket make sure the push rod is working freely and is square to the chamber bottom within A 5 B 4 GC 23 D 42 E None of the above 63 A push rod that is not square to the chamber bottom can be adjusted by installing an off set slack adjuster repositioning the chamber on the mounting bracket applying heat to the rod and bending it to fit shimming the slack adjuster to the right or left as required B amp D mTUO WS 64 When installing the air lines on the chamber A apply anon hardening compound to the hose fittings B tighten the fittings into the air inlet ports to 25 30 Lbs Ft of torque be sure each air line is mated to the correct inlet port use soapy water or leak detection solution to check for air leaks E Allthe above OO 65 When replacing the release bolt into the storage pocket on the brake chamber be sure to tighten the release bolt nut against the flat washer to 10 Lbs Ft of torque 15 Lbs Ft of torque 20 Lbs Ft of torque 25 Lbs Ft of torque None of the above mTU Ww gt 66 When mounting the brake to the bracket be sure to insta
38. he camshaft as required Fig 63 Apply a non hardening sealing compound to the hose fittings and reinstall both air lines to the chamber Fig 64 Be sure that each fitting is mated to the correct air inlet port according to markings made earlier MGM Brakes recommends the fittings be tightened to 25 30 Lbs Ft of torque into the chamber air inlet ports Using the vehicle s system air charge the spring brake with full line pressure minimum 100 psi Using only soapy water or leak detection solution NEVER USE ANY TYPE OF OIL inspect for air leaks at the air supply lines and fittings If bubbles appear tighten fittings Slightly but not over 30 Lbs Ft of torque BREATHER TUBE Figure 60 Figure 62 Figure 64 Figure 65 NOTE If the service brake clamp band was loosened to reposition the air inlet ports apply air to the spring brake and then apply and hold foot brake treadle valve down to charge the service brake chamber Test for air leaks around the circumference of the service clamp band If bubbles appear release the air from the chamber and using a plastic hammer or rubber mallet firmly tap the circumference of the clamp band Fig 65 while alternately tightening the clamp band nuts to 30 35 Lbs Ft of torque Repeat the leak test procedure If no more leaks are detected exhaust the air from the service side of the unit Now with air still applied to the spring brake side rem
39. hould be parallel to each other Fig 16b not angled or bent Fig 16a If the ears appear to be over torgued or damage is detected or suspected cautiously remove the piggyback spring brake chamber by following the directions in Section 5 of this booklet Next check the actuator to be sure it is mounted solidly to the mounting bracket by placing one hand on the head of the brake and try to move the brake up and down or to the side Fig 17 The mounting stud nuts should also be properly tightened to the manufacturer s recommended specification MGM Brakes recommends 133 155 Lbs Ft of torque clockwise Check to be sure that the split lock washers or hardened steel flat washers used by MGM Brakes are positioned properly in place between the nut and the bracket Placing the washers between the brake chamber and the bracket will allow the chamber to flex resulting in premature failure of the NON PRESSURE CHAMBER Figure 17 Inspect the NON PRESSURE CHAMBER Fig 18 for damage and or cracks around the 2 MOUNTING STUDS f damage or cracks are evident remove the complete chamber by following the directions in Section 7 of this booklet or refer to Section 3 of the MGM Brakes TR Service Manual Form 5011 Inspect the VENT HOLES in the NON PRESSURE CHAMBER to ensure they are fully open and unrestricted If the holes are restricted use a 3 8 inch drill bit and carefully ream the holes out by hand Fig 13
40. ial Vehicle Safety Alliance CVSA inspector will place a truck trailer Out of Service if the number of defective brakes is equal to or greater than of the brakes on the vehicle A 10 B 20 C 30 D 40 E None of the above 82 83 84 85 86 87 88 A defective out of adjustment brake 1 4 inch or more beyond the readjustment limit will count as 1 2 brake toward the 20 rule count as 1 full brake toward the 20 rule need to be replaced with a new unit not have any effect on the Out of Service status of the vehicle None of the above JOW m The recommended readjustment stroke for a type 30 3 inch 76 mm Long Stroke brake is A 1 5inches B 2 00 inches C 2 25inches D 2 50 inches E 3 00inches Proper brake adjustment is critical to the safe operation of commercial vehicles True False A vehicle with 20 of its brakes defective out of adjustment will be placed Out of Service True False The number of brakes required under the 20 rule for a five 5 axle truck trailer to be placed Out of Service is two 2 True False The last half of the chamber stroke is more efficient than the first half True False The maximum stroke with the brakes adjusted should be as short as possible without lining to drum contact True False Section 12 89 Because of the performance benefits of 3 inch Long Stroke chambers CVSA has increased the readjustment limit on
41. iameter Hole BREATHER TUBE you will need to drill a 1 2 inch diameter hole 1 inch from the top lip of the non pressure chamber to insert the connecting rubber elbow Be sure to drill the hole at a point closest to the centerline between the air ports Fig 40 Figure 39 NOTE On brakes equipped with an EXTERNAL BREATHER TUBE m the BREATHER TUBE must be l positioned in the upper half or upper quadrant 9 00 to 3 00 o clock facing away from the road 1 2Anch surface Fig 15 Failure to comply with these installation instructions will void the MGM Brakes Warranty without remedy m B z m Figure 40 Remove any metal burrs from around the newly drilled hole and then install a new rubber elbow on the non pressure chamber Again wipe the open end of the connector tube clean to be sure no oil is present apply a high guality rubber adhesive to the end of the tube and insert the tube into the flexible elbow to a minimum 1 2 inch engagement Fig 39 Now exhaust the air pressure from the service chamber but maintain line pressure in the spring brake Remove the RELEASE BOLT Snap the plastic END CAP or DUST PLUG tightly into the release bolt access hole Use the RELEASE BOLT to press the END CAP securely into place Fig 41 Install the RELEASE BOLT NUT and WASHER into their storage Figure 41 pocket Fig 42 on the side of the chamber or put them into the vehicle tool box or glove box
42. ing brake completely following the manufacturer s instructions Instructions for all MGM Brakes Model Series TR TR T and TR TS spring brakes are given in Section 2 of the MGM Brakes TR Service Manual Form 5011 Service Manuals for all other design series of spring brakes are also available upon request from MGM Brakes Remove the cotter pin from the yoke pin then knock out the yoke pin Fig 50 If the yoke pin is rusted frozen into the yoke it may be necessary to use an acetylene gas torch to remove the pin Be sure to observe all safety precautions when operating an acetylene gas torch and wear proper protective clothing and eye protection Next remove both air supply lines from the assembly making sure to note which air line was connected to the inlet port marked SPRING BRAKE This is important for later reinstallation reference Masking tape and a felt tip marker are handy for this purpose Fig 45 Using a 15 16 inch wrench unscrew the hex nuts on the mounting bolts and cautiously remove the old chamber from the mounting bracket Fig 51 Make sure the spring chamber of the removed actuator is fully released power spring caged and the service brake push rod is fully retracted to zero 0 stroke position i e brake fully released If the power spring is broken and installation of the release tool is impaired due to the angle of the piston apply 90 100 psi air pressure to the inlet port marked SPRING BRAKE Unl
43. lacement brake the rod would be cut approximately 3 4 inch too long Figure 28 For MGM brakes equipped with an INTEGRAL RELEASE BOLT Fig 29 i e models LTR T and LTR L3 use a 15 16 inch wrench DO NOT USE AN Figure 30 IMPACT TYPE WRENCH to turn the RELEASE BOLT counter clockwise until the power spring is fully caged Fig 30 NOTE The service chamber push rod must retract the same approximate distance the release bolt extends from the head of the brake Use the following information as a guideline LTR T pre 6 1 98 2 25 2 5 inches Type 24 and 30 Chambers LTR T post 5 31 98 3 0 inch Type 24 and 30 Chambers LTR L3 3 0 inch Type 24 and 30 Chambers A WARNING DO NOT exceed any of these recommended lengths and DO NOT exceed 50 Lbs Ft of torque on the RELEASE NUT at any time or you may damage the RELEASE BOLT or other internal components which could prevent correct manual release of the chamber NOTE With MGM Brakes Magnum piston type brakes models MG T and MJ ET Fig 31 the spring brake is manually released by turning the release bolt counter clockwise using a 3 4 inch deep socket wrench The release bolt can be completely removed on MG T models However MJ ET units have a non removable release bolt Use the following recommendations 2 Woda when manually releasing MJ ET models Figure 31 Brake Stroke Release Bolt Protrusion 2 50 Std Stroke 1 07 3 00 Long Stroke 1
44. ll spacers between the bracket and non pressure housing True False 67 Itis recommended that an impact type wrench be used to tighten the mounting bolt nuts when installing a new chamber on the vehicle True False 68 When installing a brake equipped with an external breather tube it is important that the tube be positioned facing the road surface True False 69 Itis important to inspect the push rod to be sure it is working free and is square to the chamber bottom to within 6 in any direction at any point in the chamber stroke True False 70 Failure to install the end cap securely in place on a brake equipped with an external breather tube will void the warranty True False Section 10 71 To properly dispose of an old spring brake MGM Brakes recommends A throwing it into a metal scrap bin B caging the brake and throwing it into a metal scrap bin C that the clamp band bolts be cut with an acetylene gas torch D that the coils of the power spring be cut with an acetylene gas torch E None of the above 72 When cutting the coils of the power spring with an acetylene gas torch the brake should be A caged and placed in a bucket B caged and placed in a vise on a workbench C placed on the shop floor away from combustible materials D placed into a properly constructed steel container E None ofthe above 73 The person operating the acetylene gas torch should never do so without A proper training B
45. lled with compressed air when the vehicle is in operation This air exerts pressure upon the diaphragm or piston depending upon the design of the actuator compressing the power spring thereby holding the parking brake in the disengaged position Fig 8a a b c d Figure 8 Since the service brake and parking brake chambers are isolated from each other by a seal Fig Sb the parking brake cannot interfere with the normal operation of the service brake The parking brake chamber serves two functions 1 it provides for parking the vehicle 2 it is part of the emergency brake system To park the vehicle air in this chamber is released by activating a parking brake valve generally mounted on the vehicle s dash This releases the compressed air from the parking chamber enabling the power spring to force the push rod down toward the lower service chamber This downward motion of the push rod exerts force against the service chamber s push rod causing engagement of the vehicle s foundation brakes via the yoke and slack adjuster Fig 8c The MGM manual release bolt allows easy release of spring brakes to reline brakes or move the vehicle in the absence of air pressure Fig 8d Most North American heavy duty commercial vehicles have spring brakes installed on their drive axles only while a typical trailer will have spring brakes on all axles Service chambers are typically used on front axles Firin
46. nd deepest product line in the industry Fig 1 MGM Brakes offers two types of double diaphragm spring brakes one with a detachable release tool and one with an integral release tool as well as a full line of piston diaphragm spring brakes Many models are available in both standard and 3 Inch Long Stroke designs Severe Service spring brakes targeted at industries with characteristically harsh environments such as mining livestock hauling industrial waste and refuse are also available Additionally MGM Brakes manufactures remote mount cylinders typically used as tailgate locking mechanisms as well as wedge brakes Combining this robust line up with our expansive array of service chambers it soon becomes evident just why MGM Brakes is the industry leader and why MGM Brakes products are standard equipment on more than 125 makes of heavy duty vehicles in over 40 countries SECTION 1 Foundation System The actual braking function is performed by the foundation brake which consists of the brake drum spider brake shoes and linings camshafts return springs anchor pins and rollers While the brake chamber converts air pressure into mechanical pressure the foundation brake is where motion kinetic energy is converted into heat energy friction There are three types of air operated foundation brakes used on medium and heavy duty trucks e Cam Brakes e Wedge Brakes e Disc Brakes Cam Brakes Cam brakes represent the
47. ng capability of the vehicle when the standard stroke chamber exceeds its recommended 2 inch readjustment point In addition during a roadside inspection the inspecting officer coming into contact with the 2 5 inch standard stroke chamber at the beginning of his inspection may assume that the remaining chambers on the vehicle are also 2 5 inch standard stroke and conduct his inspection accordingly Therefore although the remaining chambers have a readjustment limit of 2 5 inches and are NOT in violation when beyond 2 inches of stroke they could be cited by the officer for being out of adiustment resulting in the vehicle being placed Out of Service To identify that a vehicle is fitted with 3 inch Long Stroke spring brakes MGM Brakes has made available an identification decal Fig 78 This decal should be affixed to both sides of the vehicle s frame rail forward of the first drive axle so that it is visible to the inspecting officer If the vehicle is not equipped with the decals they can be obtained by contacting MGM Brakes ATTENTION INSPECTOR This axle is equipped with 3 LONG STROKE SPRING BRAKE CHAMBERS Maximum Readjustment Stroke 2 50 Reference North American Uniform Vehicle Out of Service Criteria Appendix A Part 11 Long Stroke Clamp Type Brake Chamber Data MGM Brakes Figure 78 A WARNING When replacing the service diaphragm of a Long Stroke chamber you
48. nvironments under the most severe conditions it is impossible to accurately determine the condition and service life remaining in critical components such as the non pressure housing mounting base flange case center section power spring and center push rod seal These are all components that are typically cleaned up and or repainted and reused in rebuilt actuators Basically witha rebuilt actuator you have no reliable way of knowing which components have been replaced and how long the unit can be expected to last SECTION 11 Brake Adjustment Proper brake adjustment is critical to the safe operation of commercial vehicles Out of Adjustment brakes are the single most sited reason for commercial vehicles to be placed Out of Service throughout North America during roadside inspections Obviously truck trailer combinations do not stop on a dime Tests have shown that a fully loaded truck trailer with fully adjusted cold brakes 200 F drum temperature traveling at a speed of 60 MPH under the best of road conditions required an average of 342 feet of stopping distance The chart below Fig 71 demonstrates the average distances required to stop a truck trailer traveling at various speeds SPEED vs TOTAL STOPPING DISTANCE SPEED PERCEPTION EFFECTIVE TOTAL BRAKE LAG MILE S FEET REACTION L DISTANCE BRAKING STOPPING PER PER DISTANCE DISTANCE DISTANCE HOUR SEC Figure 71 Average Driver Perc
49. ove the release bolt nut and washer Replace the END CAP or DUST PLUG Use the RELEASE BOLT to seat the END CAP or DUST PLUG securely Fig 66 Operating units equipped with the EXTERNAL BREATHER TUBE not having the END CAP with O RING securely in place will void the MGM Brakes warranty without remedy Figure 67 Next place the release bolt nut and washer securely into the storage pocket Fig 67 on the i chamber Tighten the nut against the flat washer to 10 Lbs Ft of torque Fig 68 The release bolt can also be stored in the vehicle toolbox or glove box Be sure to completely exhaust the air from both sides of the chamber when finished Figure 68 If the chamber is fitted with an external breather tube be sure both ends of the tube are engaged a minimum of 1 2 inch into each of the flexible rubber elbows Fig 69 The tube must be securely fastened into both elbows either by applying a high quality rubber adhesive or with hose clamps Apply Ardhesiva Hera 1 24 Minimum f Engagenent 1 2 Inch Diameter Hole Figure 69 NOTE IMPORTANT When installing any MGM Brakes model with the breather tube it is mandatory to position the breather tube in the upper half or upper quadrant 9 00 to 3 00 o clock facing away from the road surface Fig 60 Failure to comply will void the MGM Brakes Warranty without remedy on these models SECTION 10 Recommended Disposal Procedur
50. pressed air pushes against the diaphragm simultaneously compressing the return spring and extending the push rod Since the push rod is connected via a yoke and slack adjuster to the vehicle s foundation brake whether drum or disc the result is a gradual slowing of the vehicle dependent upon the amount of air pressure force that is applied to the diaphragm Spring Brake Spring brakes function as b Service Brakes e Parking Brakes e Emergency Brakes The spring brake has two chambers A The service brake chamber Fig 6a performs the normal slowing and stopping function B The parking emergency brake or piggyback i chamber Fig 6b mounted in tandem on top of Figure 6 the service brake chamber contains a diaphragm or piston and a large powerful spring a A WARNING Do not attempt to service or disassemble the spring chamber or any spring brake actuator A large spring in the spring chamber having extreme force could cause serious bodily injury if it were suddenly released due to inadvertent removal of the clamp band or tamper resistant head Currently two main types of spring brakes are commonly used worldwide for applications on trucks buses trailers and other heavy duty commercial vehicles the double diaphragm type Fig 7a and the piston diaphragm type Fig 7b The parking brake or emergency brake chamber can utilize either a piston or a diaphragm and normally remains fi
51. r determine the braking force that is generated Thin wedges with small angles produce greater braking force over larger wedges with larger angles The operation of the wedge brake is rather simple As air enters the service chamber the push rod which is against one end of the wedge assembly forces the wedge into the actuator between the adjusting and anchor pistons or plungers as they are sometimes called This moves the pistons onto the wedge assembly rollers forcing the brake shoes out contacting the lining against the drum thus slowing or stopping the vehicle Disc Brakes Disc brakes Fig 4 consist of two parts e A rotor which is a round cast iron disc that attaches to and rotates with the wheel hub e Acaliper which is an assembly that positions the brake pads relative to the rotor The brake pads linings fit into the caliper on either side of the rotor As the brake is applied the caliper squeezes the pads until they make contact with the rotor causing it and the wheel to which it is attached to slow down and stop Figure 4 SECTION 2 Spring Brakes and Service Chambers Service Brake The service brake chamber Fig 5 6a functions indepen dently of the spring brake chamber and provides stopping power for the vehicle during normal operation when full air pressure is available When Figure 5 the brake pedal is depressed compressed air fills the chamber When this occurs the influx of com
52. r pressure to the air inlet port marked Spring Brake D remove the air lines to reduce the pressure inside the chamber E Noneofthe above Exceeding 50 Lbs Ft of torque on the release bolt nut at anytime may damage the release bolt or other internal components True False The removable release bolt is essential to the release procedure and should be stored in the pocket of the brake or in the glove box or toolbox of the vehicle True False To accelerate the release procedure use an impact wrench to turn the release bolt nut clockwise until the release bolt thread extends above the nut True False 39 MGM Brakes spring brakes equipped with an integral release bolt can be fully caged by turning the release bolt clockwise until the power spring is fully caged True False 40 The release bolt of the MGM Brakes Model LTR L3 will extend 4 00 inches from the head of the brake when the unit is fully caged True False Sections 5 amp 6 41 To prevent sudden separation of the single piggyback trom the service chamber when the clamp band is removed A extend the service push rod slightly and clamp it in place with vise grip pliers B remove the pin connecting the yoke to the slack adjuster C remove the air lines to assure total release of air from within the chamber D make sure the release bolt thread extends above the nut 3 25 inches E None ofthe above 42 To help seat the clamp band firmly tap around circum
53. roke prior to taking the X and Y dimensions will result in improper alignment of the slack adjuster the push rod on the new unit being cut too short the push rod on the new unit being cut too long improper installation of the yoke and jam nut None of the above 00 24 When servicing a vehicle eguipped with MGM Brakes 3 inch Long Stroke spring brakes it is essential A 3 inch Long Stroke and 2 5 inch standard stroke chambers not be mixed B 93 inch Long Stroke diaphragms be used to service 3 inch Long Stroke units C only the piggyback be replaced if the production unit Is equipped with the MGM Brakes Welded Yoke D All the above E None of the above 56 The release bolt should be used to manually release the spring brake to assure it can be safely handled True False 57 Ifthe yoke pin is rusted or frozen in the yoke it will be necessary to remove and replace the slack adjuster True False 58 Before cutting the universal service push rod the X and Y dimensions should be estimated and marked True False 59 Prior to marking the push rod to be cut on the new unit the spring chamber and push rod on the old unit should be fully retracted to the zero stroke position True False 60 If the unit being replaced is an MGM 38 inch Long Stroke brake equipped with the MGM Brakes welded yoke replacement of the single piggyback is recommended True False Section 9 61 Prior to installin
54. roken components such as brake shoes brake drums anchor pins and spiders Cracked loose or missing brake lining or pads a Lining cracks or voids 1 16 inch in width observable on the edge of the lining b Portions of the lining segment missing so that a rivet or bolt is exposed when viewing the lining from the edge c Loose lining segments with approximately 1 16 inch movement d Complete lining segment missing Evidence of oil seepage onto or out of the brake lining or drum area This includes wet contamination of the lining edge accompanied by evidence that further contamination will occur such as oil running from the drum or bearing seal NOTE Grease on the lining edge back of shoe or drum edge and oil stains with no evidence of fresh oil leakage are not conditions for out of service consideration Any lining with a thickness less than 1 4 inch or to wear indicator if lining is so marked measured at the shoe center for drum brakes or less than 1 8 inch for disc brakes Absence of effective braking action on any steering axle of any vehicle required to have steering axle brakes including the dolly and front axle of a full trailer Mismatch of chamber size or slack adjuster length across any power unit steering axle Recognizing and providing a remedy for these problems while the vehicle is in the shop can prevent costly down time SECTION 4 Manually Releasing The Brake Before releasing the brake
55. s be sure to chock or block the wheels to prevent the vehicle from moving On units eguipped with a REMOVABLE RELEASE BOLT use a 3 4 inch 15 16 inch for type 3036 and 3636 Models wrench to remove the nut flat washer and release bolt from the storage pocket on the side of the chamber Fig 24 It is important to remember that these parts are essential to the release procedure and should be stored in the pocket provided or in the glove or toolbox of the vehicle The spring parking brake cannot be released without them Figure 24 Remove the plastic END CAP or DUST PLUG from the spring brake chamber Fig 25 Insert the RELEASE BOLT into the RELEASE BOLT ACCESS HOLE Fig 26 in the head of the brake Be sure the formed end or tee end of the bolt has been properly inserted into the hole in the piston inside the Hana chamber Insert the RELEASE BOLT until it bottoms out then turn rotate the bolt 1 4 turn clockvvise Novv lift the bolt to lock the formed end into the piston If the RELEASE BOLT does not lock into the piston vvithin at least 1 2 inch of lifi remove the bolt and repeat the proced ure When you are sure the RELEASE BOLT is locked into the piston hold it in position and install the flat washer and nut Turn the nut down against the flat a vvasher until finger 7 tight Fig 27 Figure 26 A WARNING If you are not absolutely sure that the bolt to piston engagement is correct r
56. s alignment can be obtained during the re assembly operation Figure 45 Next should you decide to remove the SERVICE and SPRING BRAKE supply lines from the single piggyback chamber be sure to mark the air line connected to the inlet port marked SPRING BRAKE Fig 45 This way it can be easily identified and properly connected to the correct inlet port during the reinstallation process lf the brake is equipped with an EXTERNAL BREATHER TUBE disconnect the tube from the rubber elbow Fig 46 Because the tube is bonded to the rubber elbow by a rubber adhesive it may be necessary to roll the rubber eloow away from the tube to achieve separation Now you re ready to remove the single piggyback from the service chamber Using a 9 16 inch wrench remove the CLAMP BAND NUTS on the SERVICE CLAMP BAND Then while holding the single piggyback chamber securely in place with one hand remove the CLAMP BAND Fig 47 and separate the spring brake from the service chamber Remove and discard the old service diaphragm Carefully inspect all visible components for damage i e return spring piston plate non pressure chamber and flange case Replace any severely worn or damaged components Place a new diaphragm into the cavity of the single piggyback chamber flange case Fig 48 and 2 align the single piggyback with the Figure 47 non pressure chamber Install a new clamp band and tighten the nuts finger tight to
57. s essential that the correct diaphragm be used when servicing a 3 inch Long Stroke chamber Obviously a 2 5 inch standard stroke diaphragm will fit into the service side of a 3 inch Long Stroke chamber However the performance characteristics of the Long Stroke chamber will be adversely affected If replacement of the complete tandem unit is required MGM Brakes recommends using a replacement unit with the Welded Yoke Figure 56 Figure 53 Figure 55 SECTION 9 Reinstalling the Combination Tandem Brake Remove the hex nuts and the flat _ k washers from the mounting bolts of the new chamber Prior to installing e the new combination tandem brake take a few minutes to inspect the mounting bracket to insure the bracket surface is free of all cracks burrs and debris that may prevent the brake from mounting flush to the bracket s surface Fig 57 Figure 57 Now install the new chamber on the bracket paying close attention to positioning the chamber air inlet ports for correct alignment to the vehicle air supply lines Fig 58 Make sure you mount the brake directly to the bracket DO NOT use any spacers washers or shims between the mounting bracket and the non pressure housing Install one flat washer and hex nut on each mounting bolt and using a 15 16 inch hand wrench DO NOT USE AN IMPACT TYPE WRENCH tighten the nuts to the MGM Brakes Figur
58. se Section 4 31 The release bolt should be inserted into the spring brake until it bottoms out then install the nut and washer then rotate the bolt 1 4 turn counter clockwise then rotate the bolt 1 2 turn clockwise then rotate the bolt 1 4 turn clockwise None of the above WO gt 32 To verify that an MGM Brakes TR2430T Model spring brake has been completely caged to zero 0 stroke the release bolt thread should extend above the nut A 2 75 inches B 3 00 inches C 3 25 inches D 3 50 inches E 4 00 inches 33 34 35 36 37 38 To manually release cage the power spring on an MGM Brakes Model MG T piston type spring brake the release bolt should A extend 4 00 inches above the head of the brake B be inserted into the brake and tightened to 40 45 Lbs Ft of torque C be completely removed using a 3 4 inch deep well socket wrench D turned clockwise until it extends 3 25 inches above the pal nut E None ofthe above Unlike double diaphragm spring brakes the unscrewing or removal of the release bolt from an MGM Brakes piston type spring brake A does not actually cage the power spring B only removes the power spring force from the slack adjuster C requires a metric socket wrench D Allthe above E A amp B To make the manual release procedure easier you can A apply lithium grease to the release bolt threads B useanairimpact wrench C apply 90 100 psi ai
59. self had experienced first hand the dangers inherent in hauling heavy loads up and down steep rugged poorly developed forestry roads This environment was a torture chamber for the braking systems commonly found on heavy trucks during that time period Frequent brake failures resulted in costly accidents and even loss of life Recognizing the need for a device that would lesson the probability of such events occurring Gummer and his two colleagues succeeded in inventing an innovative safety device which they fitted to their trucks with excellent results This MGM Brake soon swept through the logging industry and quickly revolutionized the entire trucking industry Figure 1 Vehicles fitted with spring brakes had areal safety advantage Sudden losses in emergency brake system air pressure will cause the spring brake to engage giving the operator the ability to bring a fully loaded vehicle to a safe controlled stop Manual release of the system air utilizing a dash mounted valve also provided the operator with an effective parking brake The spring brake became very popular during the ensuing decades and MGM Brakes grew to become the premier spring brake manufacturer supplier in the world Today MGM Brakes the acknow ledged leader in the development of new spring brake technology is the only full line spring brake manufacturer in the world offering more types more models and more combinations of brakes for the widest a
60. sure to inspect the VENT HOLES Fig 11b in the head of the spring brake to ensure they are fully open and unrestricted Brakes need to breathe when operating When installed on vehicles operating in dump truck ready mix concrete and other similar operations spring brakes can become encrusted with dirt or concrete which can prevent the circulation of air through the unit and entrap Figure 13 moisture and contaminants f the holes are restricted carefully ream the holes out by hand with a 3 8 inch drill bit Fig 13 BREATHER WARNING DO NOT use a tg power drill as you may damage J the diaphragm or other internal parts On units equipped with an EXTERNAL BREATHER TUBE Fig 14 be sure to inspect the breather tube and elbows for damage Make sure the BREATHER TUBE is inserted a minimum of 1 2 inch into each elbow and securely fastened with a high quality rubber Figure 15 adhesive or clamp Figure 14 NOTE IMPORTANT When installing any MGM Brakes model with the breather tube it is mandatory to position the breather tube in the upper half or upper quadrant 9 00 to 3 00 o clock facing away from the road surface Fig 15 Failure to comply will void the MGM Brakes Warranty without Figure 16 remedy on these models Inspect the SERVICE CLAMP BAND and CLAMP BAND EARS for damage and make sure the clamp band is securely in place When properly torqued 30 35 Lbs Ft the clamp band ears s
61. tion solution NEVER USE ANY TYPE OF OIL to the air lines and fittings If bubbles appear around the fittings tighten them slightly but not over 30 Lbs Ft of torque Figure 37 With the spring brake still fully charged with full line pressure apply and hold the foot brake treadle valve down to charge the service brake chamber At this time the vise grip pliers can be removed from the service push rod so that the piston can return to a normal position in the chamber Now apply soapy water or leak detection solution to the circumference of the service clamp band If bubbles appear firmly tap the circumference of the clamp ring with ahammer Fig 38 and retighten the clamp band nuts 30 35 Lbs Ft of torque until the leaks cease However if the leaks persist around the clamp band release the air from the unit loosen the clamp band and repeat the installation procedure If the new unit is equipped with an EXTERNAL BREATHER TUBE insert the end of the tube into the flexible rubber eloow extending from the NON PRESSURE HOUSING to a minimum 1 2 inch engagement Secure the tube Apply in place using the hose clamps furnished Adhesive with the unit or wipe the open end of Here the tube to be sure that no oil is present and apply a high quality rubber adhesive to the tube before inserting it into the rubber elbow Fig 39 If the old single piggyback unit was 172 Inch not equlpped with an EXTERNAL D
62. unit from the bottom of the actuator Fig 53 Next thread the yoke jam nut past the mark you made on the push rod and align the bottom edge of the nut with the mark Use a hacksaw to cut the push rod on the mark Fig 54 After cutting the rod turn the RE yuna am nut off the rod to clean up the cut Figure 54 thread Replace the jam nut back onto the push rod at a sufficient length to allow installation of the yoke and thread the yoke onto the push rod Fig 55 It is possible to reuse the yoke from the old unit provided yoke pin hole is not worn Adjust the yoke to the same Y dimension as measured from the old unit Be sure to hold the yoke to prevent it from turning and tighten jam nut against the yoke to 25 35 Lbs Ft of torque NOTE If the unit being replaced is an MGM Brakes 3 Inch Long Stroke brake there is a chance that the unit may have the MGM Brakes Welded Yoke Fig 56 attached to the push rod making removal and re use of the yoke impossible Therefore unless the non pressure housing mounting base push rod and or yoke have been damaged or are severely worn MGM Brakes recommends replacement of the single piggyback unit only Be absolutely sure that you replace the 3 inch Long Stroke piggyback with a 3 inch Long Stroke replacement unit Mixing 2 5 inch standard stroke chambers with 3 inch Long Stroke chambers across an axle is not recommended In addition it i
63. when the clamp band is removed Fig 33 Figure 33 Now following the manufacturer s recommended procedure manually release or cage the spring brake Next remove the SERVICE and SPRING BRAKE air supply lines from the chamber Be sure to mark the air line connected to the inlet port marked SPRING BRAKE so it can be easily identified and properly connected to the correct inlet port during the installation Bun process Fig 34 Figure 35 If the brake is equipped with an EXTERNAL BREATHER TUBE Fig 35 disconnect the tube from the rubber elbow Because the tube is bonded to the rubber elbow by a rubber adhesive it may be necessary to roll the rubber elbow away from the tube to achieve separation Now you re ready to remove the single piggyback chamber Using a 9 16 inch wrench remove the CLAMP BAND NUTS on the SERVICE CLAMP BAND Then while holding the single piggyback chamber securely in place with one hand remove the CLAMP BAND Fig 36 and separate the spring brake from the service chamber Figure 36 Once you have removed the spring brake take the opportunity to inspect all the parts in the service chamber and replace any parts that may be damaged or worn especially the diaphragm and clamp band Before installing the new single piggyback spring brake make sure it is fully released to zero stroke Now position the new diaphragm into the bottom recess of the single piggyback chamber Fig 37

5043 - Cumberland Trucks

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