5003 - Cumberland Trucks
Contents
1. What do I do for a replacement Unless the non pressure chamber NPC or mounting base H push rod I and or yoke J have been damaged or are severely worn replacement of the single piggyback unit ONLY is recommended NOTE See MGM Brakes Product Bulletin 03 003 Otherwise if replacement of the combination tandem unit is required it should be replaced with a welded yoke replacement unit ONLY NOTE See MGM Brakes Product Bulletin 03 003 Do not attempt to replace a welded yoke actuator with a universal cut to fit aftermarket all threaded replacement unit While it may be possible to cut the push rod at or near the correct length the combination of the threaded yoke and jam nut K may prevent the unit from achieving zero stroke Also if the push rod opening in the non pressure chamber NPC or mounting base is large enough the jam nut will protrude into the NPC and may damage the protective stone shield NOTE See MGM Brakes Technical Bulletin 03 002 What happens if I replace long stroke chamber with a different stroke unit Due to the difference in operational characteristics of 2 5 inch and 3 inch stroke chambers mixing strokes across an axle may cause an imbalance in the braking capability of the vehicle This may result in the vehicle being pulled toward the side with the long stroke unit during emergency stopping situations2. IMPORTANT NOTE When servicing a truck trailer bus equipped with 3 inch long stroke actuators it is crucial that you replace like for like and do not install a standard 2 5 inch stroke actuator in place of the long stroke unit NOTE See MGM Brakes Technical Bulletin 02 002 What s the readjustment limit for 3 inch long stroke chambers The readjustment limit has been set at 2 50 inches for 3 inch long stroke actuators Is the service side diaphragm different for a 3 inch long stroke brake Yes When replacing the service diaphragm of a 3 inch long stroke chamber you MUST replace with a 3 inch long stroke diaphragm Installation of an incorrect diaphragm will change the performance characteristics of the actuator adversely affecting its operating efficiency and may result in a catastrophic failure The service brake is not applying adequate force 1 Improper brake adjustment With brakes applied check the brake chamber push rod to see if the orange MGM Brakes Stroke Alert stripe is showing L If so readjust the slack adjuster in accordance with its manufacturer s instructions Be certain that the spring parking brake chamber is fully released during this adjustment 2 Available air pressure to brake chamber is insufficient M Is the system air pressure gauge reading normal If it s reading low check compressor for proper operation Look for kinked or blocked air
3. information All available literature can be downloaded at your convenience 24 hours a day 7 days a week The MGM Brakes BrakeTECH Service Self Study Program is also available free of charge and allows participants to learn common procedures for maintaining and servicing spring brakes and service chambers Also keep in mind that most heavy duty truck trailer bus parts dealers and fleet specialists can provide MGM Brakes product information and genuine OEM service replacement assemblies At MGM Brakes our commitment doesn t stop when you buy our products The way we See it it s just beginning PUBLICATIONS The following publications have been referenced in this guide All can be downloaded from the MGM Brakes website where hard copies can also be requested Please visit our website or contact your local regional MGM Brakes representative for more information e MGM Brakes Product Bulletin 03 003 Replacement Units for MGM Brakes 3 Inch Long Stroke Chambers with Welded Yokes MGM Brakes Technical Bulletin 03 002 Field Replacement of MGM Brakes Chambers Equipped with Welded Yokes MGM Brakes Technical Bulletin 02 002 Mixing Standard amp Long Stroke Chambers MGM Brakes Model TR Series Service Manual Form No 5011 MGM Brakes Model LTR Series Service Manual Form No 5042 MGM Brakes Model MAGNUM Performance Plus MJ Series Service Manual Form No 5044 e M
4. lines Check for defective valves 3 4 Excessive brake lining or drum wear Handle in accordance with the manufacturer s inspection instructions Check brake chambers to ensure they are fully released when brakes are not applied Also check for incompatibility of truck and trailer brake chambers Improper slack adjuster operation or Set up The angle made by the brake actuator push rod with respect to the mounting 12 surface should be perpendicular within 3 from zero to full stroke The push rod clearance hole N in the non pressure chamber NPC or mounting base for the brake actuator push rod should not be elongated or show evidence of rubbing or wear from the rod With brakes applied using 80 90 psi of air pressure the angle O between the push rod and slack adjuster should never beless than 90 Follow the slack adjuster manufacturer s recommendation for proper operation and set up 5 Damage to mounting bracket or non pressure chamber NPC or mounting base Check bracket and NPC for cracks or other signs of damage Verify that mounting nut torque is as specified in the appropriate MGM Brakes Service Manual If structural damage is found replace the defective parts immediately Be sure to follow MGM Brakes Service Manual instructions for proper removal and reinstallation 6 Improper sizing of brake chambers or excessive payload weight Consult with vehicl
5. to determine whether the gap S between the top of the piston and spring chamber housing head is approximately 200 inches If not replace the single piggyback with an MGM Brakes Piggyback or Piggyback Plus Kit kit includes piggyback clampband and diaphragm 4 Broken service chamber return spring T Remove the piggyback and service diaphragm U then inspect return spring T If broken replace with a new return spring and new diaphragm Order ONLY genuine MGM Brakes brand replacement parts and install in accordance with instructions in the appropriate MGM Brakes Service Manual 18 5 Ruptured diaphragm V or damaged push rod seal W Check for leakage at the parking chamber vent holes or through the release bolt hole Remove the release bolt access hole dust cap X and apply air to spring brakes release If you feel or hear air escaping in these areas the diaphragm is defective Replace entire piggyback as instructed in appropriate MGM Brakes Service Manual 6 If air applied to the spring chamber has a tendency to apply the service brake or to cause the service exhaust valve to leak the push rod seal W is leaking To verify disconnect the service air line and apply air to the parking chamber If air is detected escaping through the open service air inlet port the push rod seal is leaking Replace the entire piggyback as instructed in the appropriate MGM Brakes Service Manual A
6. GM Brakes BrakeTECH Service Self Study Training Program Form No 5043 Brakes A Division of Indian Head Industries Inc 8530 Cliff Cameron Drive Charlotte North Carolina 28269 9786 Phone 800 527 1534 704 547 7411 Fax 704 547 9367 E mail mail mgmbrakes com Website www mgmbrakes com
7. MGM Brakes TROUBLESHOOTING GUIDE FAST ANSWERS FOR TOUGH BRAKE PROBLEMS FAST BHAKE TROUBLE SHOOTING GUIDE INDEX INTRODUCTION 3 3 4 Q amp A e Why does my spring brake have square POTS 5 e Why is the yoke welded to the service pushrod cues nari Reha gH Yo neni 7 e What do I do for a replacement 7 What happens if I replace a long stroke chamber with a different stroke unit 9 What s the readjustment limit for 3 inch long stroke chambers eese 9 e Is the service side diaphragm different for a 3 inch long stroke 10 The service brake is not applying adequate LON cett 10 The parking brake 18 not holding There is insufficient parking force 16 The parking brake will not stay released dragging brakes 17 Service brakes apply or the service exhaust valve leaks when air is applied to the parking brake 21 21 PUBLICATIONS 23 MGM BRAKES wants to help you keep your trucks trailers and buses on the road At MGM Brakes we know how important it is to keep your vehicles on the road and out of the garage so the whole idea behind this F
8. The parking brake is not holding There is insufficient parking force Refer to the possible causes just discussed under The service brake is not applying adequate force Broken power spring Remove the dust plug P from the release bolt access hole of the brake chamber Use a flashlight to check for evidence of spring breakage Brake chamber stroke Q can also be checked while applying and releasing the parking brake If the expected range of motion is not observed the spring may be broken Also the contents will rattle if the piggy back is removed and shaken indicating a probable broken spring Replace with the appropriate MGM Brakes piggyback 16 ts NH ww 3 en JN The parking brake will not stay released dragging brakes l Available air pressure to the brake chamber is insufficient Is the system air pressure gauge reading normal If it s low check the compressor for proper operation Look for kinked or blocked airlines Check for defective valves 2 Service application air is not exhausting properly Apply and release service brakes while listening to exhaust If the sound is not normal check for kinked or blocked air lines or defective valves 3 The spring brake piston is binding before it is fully retracted Release the parking brake Remove the dust plug P and apply 90 100 psi of air pressure Look into the dust plug hole
9. ast Brake Trouble Shooting Guide is to answer questions you might have and help you find a solution to problems fast But first here are a few common sense precautions to take before you start PRECAUTIONS 1 Besure to turn off the engine before you work under any vehicle 2 Always chock the wheels Depleting air system pressure may allow the vehicle to roll Keep your hands away from actuator push rods and slack adjusters they may apply as the system pressure drops 3 Never connect or disconnect a hose or line that contains air pressure It may whip as air escapes Never remove component or pipe plug unless you re sure that all system air pressure has been depleted Never exceed recommended air pressure and always wear safety glasses while working with air brake systems Never look directly into air lines or fittings and never direct them at anyone Never try to dismantle a component until you have read and understand the recom mended procedures Some units contain powerful springs and injury is possible if they are not properly dismantled Use only the correct tools and observe all precautions relative to the use of those tools INSPECTION Before you begin testing the air brake system it s important to perform the following checks 1 Examine all tubing and or hoses for signs of kinks or dents 2 Check all tubing and or hoses for signs of wear drying out or damage due to
10. e manufacturer docu mentation or representative 7 Brake chamber or air system lines fittings valves leakage There may be a system leak if the compressor comes on often or pressure is unable to be maintained Examine all lines fittings and valves for proper connection and leakage If no problems are found inspect brake chambers for leakage Listen for an 14 audible sound or spray clampbands with a soap water solution and inspect for air bubbles If leakage is found at the service side clampband area check the torque on clampband bolts and verify it is adequate per the appropriate MGM Brakes Service Manual If the leakage persists replace the diaphragm and clampbands per instructions in the manual CAUTION If leakage is found at a spring side crimp area b end plug c first valve in air line ahead of the spring brake emergency release replace the valve if required or replace the entire piggyback per instructions in the appropriate MGM Brakes Service Manual Be sure to install the release bolt and cage the spring by following the manual s instructions prior to removal Never attempt to open or disassemble the single piggyback chamber on any spring brake 8 Improper push rod length 1 This may be the problem if proper rod angularity is difficult to achieve and or frequent readjustment is necessary Consult the vehicle manufacturer for proper push rod length
11. excessive heat 3 Check the suspension of all tubing and or hoses They should be supported and should not vibrate Position them so they will not be subject to excessive heat or rub or wear against another part 4 Determine the brand name model and or part number of the spring brake Q amp A Now you re ready to start Here s a list of commonly asked questions and complaints in red along with possible causes and recommendations on how to correct them Why does my spring brake have square air inlet ports Trucks tractors trailers and buses are being manufactured with both standard 2 5 inch stroke and 3 inch ong stroke spring brakes and service chambers so it is important to know how to identify what is on your equipment 1 3 long stroke chambers be easily identified by their square air inlet ports A trapezoidal I D tags B and servicing instructions embossed into the aluminum center case C 2 Long stroke service chambers are identified by a 1 2 inch high square raised embossment on top of the pressure cap D along with the trapezoidal I D tag E and embossed instructions on the pressure cap F Why is the yoke welded to the service push rod Many 3 inch ong stroke spring brakes and service chambers are equipped with welded yokes G which are permanently attached to the service push rod making removal and reuse virtually impossible G j
12. utoslack over adjustment or camshaft linkage binding Consult the manufacturer s service manual Broken power spring Y or return spring Z in parking brake section A broken power spring can be diagnosed as discussed in the previous section A broken return spring in the parking chamber is difficult to diagnose Either case requires the complete replacement of the piggyback Service brakes apply or the service exhaust valve leaks when air is applied to the parking brake l Air is leaking through the push rod seal W Replace the entire piggyback as instructed in the appropriate MGM Brakes Service Manual NOTE As the industry leader MGM Brakes backs its products with strong warranties and an equally strong commitment to the people and companies who buy them While the Fast Brake Trouble Shooting Guide is a result of that dedication our commitment doesn t end here The air brake system is a complex web of valves tubing and other components and try as we might it s impossible to cover every trouble shooting eventuality If you need advice on problems that go beyond what we have presented here feel free to call your MGM Brakes Sales Representative or contact our Customer Service Department at 1 800 527 1534 Please visit the MGM Brakes website at www MGMbBrakes com to reference our publications including technical bulletins service manuals product brochures and general catalog
Download Pdf Manuals
Related Search