BENDIX BW7499 User's Manual
Contents
1. Bendix Versajust Automatic Slack Adjuster DESCRIPTION The Bendix Versajust automatic slack adjuster is designed for use on cam actuated drum brakes the type in use on most highway vehicles Like a manual slack adjuster the Versajust slack adjuster multiplies and transforms the linear force of the air actuator into a rotational force or torque which is used to apply the foundation brake In addition the Versajust slack adjuster automatically adjusts the clearance between the brake lining and drum to compensate for wear A variety of Bendix Versajust slack adjuster configurations are offered including both straight arm and s yoke offset models The Versajust slack adjuster is offered in arm lengths of 5 5 2 and 6 inches and worm gear splines to accommodate the standard 1 s and 1 2 SAE 10C 24 and 28 tooth splines Either of two yoke designs easy on and quick connect in combination with an external manual adjuster hex provides for convenient installation and maintenance of the Bendix Versajust slack adjuster Note The manual adjuster hex is intended for use during installation CAUTION Automatic slack adjusters should not be adjusted manually to correct excessive push rod stroke OPERATION GENERAL The automatic adjustment provided by the Bendix Versajust slack adjuster results in consistent brake lining to drum clearance and brake actuator stroke The key to its operation is the ability to compl2. 15 x4 16 5 x7 AL Factor Brake Front Tractor Truck Brake or Bus Brake CHART 3 AL FACTOR BENDIX VERSAJUST SLACK ADJUSTER REMOVAL Note Make certain the vehicle has been prepared according to the instructions under the heading GENERAL SAFETY GUIDELINES in this manual 1 If the Versajust slack adjuster is equipped with the easy on yoke assembly illustrated in Figure 2 A Loosen the brake actuator push rod jam nut and run it back on the brake actuator push rod approximately s inch 16 5 x7 B Loosen the easy on yoke adapter and run it back on the brake actuator push rod until it is free of the yoke C Rotate the manual adjustment hex counterclockwise until the Versajust slack adjuster is clear of the brake actuator push rod Note Considerably more torque is required to rotate the manual adjustment hex counterclockwise than is necessary to rotate it clockwise The torque may be as high as 70 foot pounds 2 Ifthe Bendix Versajust slack adjuster is equipped with the quick connect yoke assembly illustrated in Figure 3 A Rotate the Versajust slack adjuster s manual adjustment hex counterclockwise until the brake actuator push rod begins to move just out of the actuator B Pinch the legs of the retaining ring together and pull the Versajust slack adjuster away from the brake actuator push rod until the adapter bushing is free of the yoke Remove the retaining ring from the adapter bushing C
3. The Bendix Versajust automatic slack adjuster can replace a manual slack or competitive automatic slack adjuster provided some considerations are kept in mind 1 Excessive duty cycles high application pressures and brake force compounding can result in reduced slack adjuster durability 2 Determine that the AL factor of the vehicle to be retrofitted is 195 or less To determine the AL factor multiply the slack adjuster arm length from the center of the cam spline to the center of the yoke pin hole in use times the brake chamber size For example a Type 30 brake chamber connected to a 6 inch arm slack adjuster A 30 square inches L 6 inches therefore 30 x 6 180 AL factor 3 Make sure the foundation brake components are in good condition Excessive drum out of roundness will result in excessive lining wear See the n Service Inspection section of this manual 4 In order to select the proper slack adjuster choose a Versajust slack adjuster with the same arm length spline size push rod thread size and offset as the slack adjuster it is replacing 5 When retrofitting the Versajust slack adjuster make certain to read the instructions packaged with all service replacement Versajust slack adjusters The Bendix Versajust Slack Adjuster Troubleshooting Chart Brake Actuator stroke is too long WARNING Automatic slack adjusters should not be manually adjusted in an effort to correct excessive push rod strok
4. clockwise rotation adjustment will decrease progressively as the brake nears proper adjustment If the Versajust slack adjuster fails to perform as described it will be necessary to repair or replace it 4 Manually re adjust the Versajust slack adjuster being tested before returning the vehicle to service See section nstallation Step 6 Note While it is possible to use the automatic adjustment feature of the Versajust slack adjuster to bring the brake back into adjustment this process will require numerous applications and COMPLETE RELEASES the number of applications depends on how much the slack was de adjusted 6 BRAKE MAINTENANCE INSPECTION Note Make certain the vehicle has been prepared according to the instructions under the heading GENERAL SAFETY GUIDELINES in this manual The following test can be used to inspect the maintenance condition of the foundation brake and to determine how much of the chamber stroke is caused by the condition of the foundation brake 1 Always chock the wheels to keep the vehicle from moving 2 Raise the axle so the wheel can be rotated 3 Adjust the slack adjuster to produce light brake drag with wheel rotation 4 Apply the brake to 80 90 psi and measure the stroke See Item 3 of In Service Inspection for pressure tips 5 If the stroke significantly exceeds the values shown in Chart 3 below the brake may be out of the norm and brake maintenance may be required Trailer
5. easy on yoke assembly only Note Installing any other type of push rod extender is not recommended These devices may loosen over time and result in an improperly adjusted brake Inspect the foundation brake brake chamber and related components Make certain the camshaft bushings and seals are not excessively worn Lubricate the camshaft bushings Check the brake chamber bracket for cracks and excessive corrosion The brake actuator push rod should not be loose or bent and the return spring should be firm Replace parts that are suspect Wire brush the foundation brake camshaft to loosen contamination and wipe clean Depending on 3 environmental conditions an application of anti seize compound to both the camshaft and worm gear spline may facilitate later slack removal INSTALLATION 1 Select the proper Bendix Versajust slack adjuster 2 Install the Versajust slack adjuster on the brake camshaft 3 If the Versajust slack adjuster has the easy on yoke see Figure 3 position the brake actuator push rod jam nut approximately 1 1s inches from the end of the brake actuator push rod Thread the easy on yoke adapter on the brake actuator push rod until it is approximately s inch from the end of the brake actuator push rod end Turn the Versajust slack adjuster manual adjustment hex clockwise until the adapter extends into the threaded bore of the yoke approximately s inch Thread the adapter into the yoke and
6. make manual adjustments of an automatic slack adjuster once it can no longer automatically adjust the brakes Manual adjustment DOES NOT fix the underlying wheel end adjustment problem As soon as possible have the vehicle inspected by a qualified technician or consult the manufacturer s troubleshooting guidelines to find and fix the problem TESTING THE BENDIX VERSAJUST ADJUSTER MECHANISM The following test can be made to determine if the Bendix Versajust adjuster mechanism is functioning properly 1 With the brakes released and the vehicle wheels blocked de adjust the brakes by rotating the manual adjustment hex counterclockwise approximately 2 to 1 revolution Note Considerable torque is required to rotate the manual adjustment hex counterclockwise and should be considered normal The required torque may be as high as 70 foot pounds 2 Using a straight edge scribe a line across the manual adjustment hex head and slack adjuster body Refer to Figure 6 ADJUSTER HEX ROTATES CLOCKWISE DURING ADJUSTMENT GREASE FITTING FIGURE 6 TESTING ADJUSTER MECHANISM 3 Apply and COMPLETELY RELEASE the service brakes several times while observing the manual adjustment hex and the scribed line The Bendix Versajust slack adjuster manual adjustment hex should rotate clockwise during the application and remain stationary during release No counterclockwise rotation of the hex should be observed The amount of
7. pulled upward The teeth on the link mesh with the adjuster mechanism pinion As the link is pulled it travels first through its free play and then causes the pinion to rotate Rotation of the pinion is transmitted through the clutch spring to the worm 1 GENERAL SAFETY GUIDELINES WARNING PLEASE READ AND FOLLOW THESE INSTRUCTIONS TO AVOID PERSONAL INJURY OR DEATH When working on or around a vehicle the following general precautions should be observed at all times 1 Park the vehicle on a level surface apply the parking brakes and always block the wheels Always wear safety glasses Stop the engine and remove ignition key when working under or around the vehicle When working in the engine compartment the engine should be shut off and the ignition key should be removed Where circumstances require that the engine be in operation EXTREME CAUTION should be used to prevent personal injury resulting from contact with moving rotating leaking heated or electrically charged components Do not attempt to install remove disassemble or assemble a component until you have read and thoroughly understand the recommended procedures Use only the proper tools and observe all precautions pertaining to use of those tools If the work is being performed on the vehicle s air brake system or any auxiliary pressurized air systems make certain to drain the air pressure from all reservoirs before beginning ANY work on the vehicle I
8. tighten to 10 foot pounds The installation below depicts the angle of a properly installed Versajust slack adjuster FIGURE 5 INSTALLATION ANGLE Slack Adjuster Arm Length Angle CHART 1 SLACK ADJUSTER ARM LENGTH ANGLE 4 lf the Versajust slack adjuster has the quick connect yoke see Figure 4 position the brake actuator push rod jam nut approximately 1 inch from the end of the brake actuator push rod Thread the quick connect adapter bushing on the brake actuator push rod until it is flush with the end of the brake actuator push rod Install the retaining ring on the adapter bushing making certain itis in the adapter bushing groove Turn the Versajust slack adjuster manual adjustment hex clockwise until the adapter bushing begins to enter the yoke Fully compress the retaining ring legs and continue turning the Versajust slack adjuster manual adjustment hex until the adapter bushing is completely in the yoke Allow the retaining ring to expand into the corresponding groove in the yoke Make certain the retaining ring is seated in both the yoke and the adapter bushing groove by manually pulling the Versajust slack adjuster arm attempting to separate the adapter bushing and yoke 5 Run the brake actuator push rod jam nut down against the adapter or adapter bushing Hold the adapter or adapter bushing hex with a wrench and tighten the jam nut to 300 400 inch pounds for the 2 20 thread and 400 600 inch pounds f
9. Rotate the manual adjustment hex counterclockwise until the Versajust slack adjuster is clear of the brake actuator push rod 3 Remove the Versajust slack adjuster from the camshaft of the foundation brake by removing the retaining clip and any spacers or washers that may be present DISASSEMBLY GENERAL Areasonable level of cleanliness should be observed when working on the Versajust slack adjuster Clean the exterior before disassembly The following disassembly and assembly procedure is presented for reference purposes and presupposes that a rebuild or repair of the Versajust slack adjuster is being undertaken Several replacement parts and maintenance kits are available which do not require full disassembly The instructions provided with these parts and kits should be followed in lieu of the instructions presented here 1 Clamp the Versajust slack adjuster ARM in a bench vise Do not clamp across the portion of the body that contains the adjuster assembly or worm gear Using a wire brush thoroughly clean the exterior of the slack adjuster paying particular attention to the area around the manual adjustment hex and its retaining ring Wipe all loose contaminants away before proceeding 2 Remove the cotter pins and washers from the yoke pin and link pin 3 Remove the yoke pin and link pin and separate the yoke from the Versajust slack adjuster 4 Ifthe Versajust slack adjuster has a yoke pin bushing press it out of the slac
10. ase is due to the direction of the coil windings of each YOKE DESIGNS The Bendix Versajust slack adjuster may be equipped with either of two yoke designs Both are designed to permit installation or removal of the slack adjuster along with its yoke body and its attached adjusting linkage The brake actuator push rod must thread into the adapter a minimum of 2 inch and must not extend more than s4 inch beyond the other end of the adapter The yoke adapters quick connect amp easy on have either a 1 or 1 4 inch hex to allow tightening of the brake actuator push rod jam nut EASY ON YOKE REFER TO FIGURE 2 The easy on yoke assembly consists of an adapter which is threaded internally to match the push rod threads and externally to match female threads in the yoke A special extended yoke adapter is also available as a separate service item The extended adapter is 2 inch longer than the standard and is primarily intended for use when the existing brake actuator push rod is too short PUSH ROD JAM NUT MOUNTING STUD ADAPTER FIGURE 2 EASY ON YOKE ASSEMBLY QUICK CONNECT YOKE The adapter bushing in this case is threaded internally to match the push rod but is designed to slide into the yoke A retainer ring is used to secure the adapter bushing in the yoke Refer to Figure 3 A With the brake chamber in the released position place a square or an equivalent object so that one edge is parall
11. e because this condition indicates that a problem exists with the automatic adjuster with the the adjuster or with related foundation brake components which manual adjustment will not fix 2 Brakes dragging apparent over adjustment of brakes C Excessive clearance between components yoke pin yoke link pin link yoke pin body E Weak or broken brake actuator return springs Weak or broken brake shoe installation of return spring Worn or broken foundation brake components including camshaft bushings brake chamber bracket etc Versajust adjuster mechanism not functioning Brake drum worn excessively machined bell mouthed excessive thermal expansion J Versajust slack adjuster improperly installed A Versajust slack adjuster improperly installed Too close to actuator brakes can t fully release C Spring brakes not fully retracting E Vehicle brake torque imbalance More work done by some brakes than others thermal expansion of drums F Brake drum out of round excessive thermal expansion G Air system malfunction not exhausting completely CHART 4 TROUBLESHOOTING SYMPTOM CAUSE REMEDY A Loose actuator push rod jam nut A Reposition components and torque to specification B Excessive clearance between adapter B Replace damaged or worn parts adapter bushing and yoke due to wear C Replace worn parts D Damaged worn D Replace damaged pa
12. el to the actuator push rod while the other edge bisects the brake camshaft Measure the distance from the push rod end to the vertical edge of the square and compare it to the values in Figure 4 BRAKE ACTUATOR PUSH ROD SQUARE EE ee e E DISTANCE A MOUNTING STUD A Std Quick Connect or Easy On Adapter Slack Adjuster Arm Length A Extended Easy On Adapter 15 6 31 32 Zhe 31 32 1 6 33 16 2 he 3he O E he 35 16 Wie 3 46 PUSH ROD FIGURE 4 MEASURING THE BRAKE ACTUATOR PUSH RETAINING RING ROD B If the measurement is less than the minimum shown JAM NUT MOUNTING STUD ADAPTER BUSHING FIGURE 3 QUICK CONNECT YOKE ASSEMBLY INITIAL INSTALLATION PREPARATION 1 Ifnecessary carefully remove the manual or automatic slack adjuster currently installed including the brake chamber yoke assembly 2 Before mounting the Bendix Versajust slack adjuster on the camshaft check the brake chamber push rod length to determine whether shortening or replacement is required To accomplish this in Figure 4 the brake actuator push rod must be shortened If the measurement is greater than the maximum values the brake actuator push rod may require replacement The extended adapter available as a separate service part s 18 pc no 297700 and 2 20 pc no 297701 may avoid the need to replace the brake actuator push rod The extended adapter is available for the
13. enance Inspection presented in this manual should determine how much of the long stroke condition is caused by the condition of the foundation brake The Bendix Versajust slack adjuster can be tested using the instructions presented in this manual under Testing the Bendix Versajust Adjuster Mechanism The automatic slack adjuster is not designed to function as a manual adjuster once it is unable to maintain adjustment automatically Manual adjustment should be done only as a temporary measure to correct brake adjustment in an emergency situation The routine manual adjustment of an automatic slack adjuster that is still within adjustment limits may shorten its service life Automatic slack adjusters should not be manually adjusted in an effort to correct excessive push rod stroke This condition indicates that a problem exists with the automatic adjuster with the installation of the adjuster or with related foundation brake components which manual adjustment will not fix Replacement of the automatic slack adjuster or other foundation brake components may be necessary Consult with the manufacturer s troubleshooting guidelines to find and fix the problem WARNING Manual adjustment of automatic slack adjusters is a dangerous practice that could have serious consequences This is because it can give the operator a false sense of security about the effectiveness of the brakes which are likely to go out of adjustment again soon Do not
14. ete the brake adjustment during the early part of each brake application and to cease adjusting as resistance to brake cam rotation begins to build This aspect of the adjuster mechanism s operation prevents over adjustment caused by lining compression actuator bracket deflection drum and foundation brake component distortion or brake component wear The Versajust slack adjuster incorporates a clutch type adjuster mechanism that continuously adjusts in very small increments as lining and drum wear occurs The adjustments made by the Versajust slack adjuster are therefore not in specific increments relative to actuator stroke Compatible with Bendix ASA 5 Automatic Slack Adjusters ERRE MANUAL ADJUSTMENT LUBE FITTING FIGURE 1 BENDIX VERSAJUST AUTOMATIC SLACK ADJUSTER Note that the Versajust automatic slack adjuster is compatible with Bendix ASA 5 automatic slack adjusters Therefore it is acceptable to have a Versajust automatic slack adjuster on one side of the axle and an ASA 5 automatic slack adjuster on the other side of the same axle BRAKE APPLICATION When the brakes are applied the linear travel of the brake actuator s push rod causes the Versajust slack adjuster to rotate the foundation brake camshaft which in turn begins to force the brake shoes into contact with the drum When the Versajust slack adjuster rotates the yoke assembly pivots on the yoke pin causing the link to be
15. f the vehicle is equipped with a Bendix AD IS air dryer system or a dryer and shaft Worm and shaft rotation results in worm gear rotation which in turn adjusts or repositions the brake camshaft When the foundation brake shoes contact the drum the camshaft begins to resist rotation and friction between the worm gear and worm builds preventing further rotation of the worm Brake adjustment ceases at this point and further rotation of the Bendix Versajust slack adjuster will cause the pinion and clutch spring to slip The free play between the link teeth and pinion results in a predetermined lining to drum clearance BRAKE RELEASE When the brake application is released the brake actuator push rod returns the Versajust slack adjuster to the released position During release the Versajust slack adjuster rotates back toward the actuator causing the brake camshaft to again rotate but in the opposite direction and the brake shoes begin to move away from the drum As the Versajust slack adjuster rotates back to the release position the yoke again pivots causing the link to be pushed downward into the slack adjuster body The free play between the link teeth and pinion is taken up during the initial part of the release Continued movement 2 reservoir module be sure to drain the purge reservoir Following the vehicle manufacturer s recommended procedures deactivate the electrical system in a manner that safe
16. k adjuster arm 5 No further disassembly of the Versajust slack adjuster is permitted CLEANING AND INSPECTION 1 Inspect the worm gear camshaft splines for damage lf damaged replace the Versajust slack adjuster 2 Clean and inspect the yoke pin and link pin holes in the yoke the adjuster link and the slack adjuster body The holes should be visually round with no perceptible egg shaping Anew yoke pin and link pin can be used to make this inspection If this condition is noted the affected part must be replaced 3 Clean out the retaining ring grooves in the yoke REASSEMBLY 1 Ifthe Versajust slack adjuster uses a yoke pin bushing press it into the slack adjuster arm 2 Depending on environmental conditions an application of anti seize compound to both the yoke and link pins may facilitate later removal Install the yoke and secure it to the Versajust slack adjuster body and link using the yoke pin and link pin Install washers and cotter pins in the yoke pin and link pin and secure each Bend each leg of the cotter pins to a minimum of 25 degrees creating an included angle of at least 50 degrees between the legs 3 Lubricate the automatic slack adjuster through the lube fitting with a quality multipurpose chassis lubricant N L G I Grade 2 Lubricate the slack adjuster until clean lubricant flows from the grease relief opening in the boot RETROFITTING THE BENDIX VERSAJUST SLACK ADJUSTER PREPARATION
17. ly removes all electrical power from the vehicle Never exceed manufacturer s recommended pressures Never connect or disconnect a hose or line containing pressure it may whip Never remove a component or plug unless you are certain all system pressure has been depleted Use only genuine Bendix brand replacement parts components and kits Replacement hardware tubing hose fittings etc must be of equivalent size type and strength as original equipment and be designed specifically for such applications and systems Components with stripped threads or damaged parts should be replaced rather than repaired Do not attempt repairs requiring machining or welding unless specifically stated and approved by the vehicle and component manufacturer Prior to returning the vehicle to service make certain all components and systems are restored to their proper operating condition For vehicles with Automatic Traction Control ATC the ATC function must be disabled ATC indicator lamp should be ON prior to performing any vehicle maintenance where one or more wheels on a drive axle are lifted off the ground and moving of the Versajust slack adjuster toward the released position causes the link to rotate the pinion The anti reverse spring prevents counterclockwise rotation of the shaft and worm causing the pinion and clutch spring to slip The gripping action of the anti reverse spring and slippage of the clutch spring during rele
18. ody link Replace these parts if looseness appears excessive Make certain the brake actuator push rod jam nut is tight against the yoke adapter 2 Inspect the Versajust slack adjuster for physical damage paying particular attention to the link boot and yoke Inspect for bent broken loose or misaligned brake actuator push rods and cracked or damaged brake actuator brackets Repair or replace any components found to be damaged ACTUATOR STROKE TABLE STANDARD STROKE Recommended Brake Actuator Maximum Size Operating Stroke LONG STROKE Recommended Maximum Size Operating Stroke Brake Actuator CHART 2 ACTUATOR STROKE TABLE 3 Measure the brake actuator push rod stroke while making an 80 90 psi service brake application Actuator push rod strokes should not exceed the values shown in Chart 2 on this page The correct pressure for this test can be achieved as follows Build the system pressure up to a 100 psi reading on the vehicle gauge Shut the engine off Fan the brakes to attain a 90 95 psi reading Make and hold a full brake application while the strokes are checked IF THE SLACK ADJUSTER DOES NOT AUTOMATICALLY ADJUST THE BRAKES If the actuator stroke exceeds those shown in the stroke table inspection of the foundation brake and or the automatic slack is necessary Maintenance of the foundation brake may be a factor in the excessive stroke conditions Inspecting the foundation brake per the Brake Maint
19. or the s 18 thread 6 Manually adjust the brakes Note The vehicle brakes should be adjusted using either the vehicle or brake manufacturer s recommendation If these are not available the following procedure can be used Rotate the manual adjustment hex clockwise until the linings are snug against the drum Turn the adjustment hex counterclockwise 2 turn Pull the actuator push rod to confirm that approximately 2 inch of push rod free stroke exists Apply 85 psi and check that the push rod stroke is below the readjustment limit If the stroke exceeds the readjustment limit check the condition of the foundation brake Refer to the Brake Maintenance Inspection in this document 7 Manually uncage the spring brakes before returning the vehicle to service 8 With the Versajust slack adjuster installed check to ensure clearance requirements with the brake fully released and at the actuator s maximum stroke Also consider clearances with the vehicle suspension springs depressed to the jounce bumpers as well as in rebound PREVENTIVE MAINTENANCE Important Always review the Bendix Warranty Policy before performing any intrusive maintenance procedures A warranty may be voided if intrusive maintenance is performed during the warranty period No two vehicles operate under identical conditions As a result maintenance intervals may vary Experience is a valuable guide in determining the best maintenance interval for ai
20. r brake system components Also observe any more frequent brake adjustment inspections or maintenance intervals specified by the vehicle manufacturer At a minimum the Versajust slack adjuster should be inspected every 3 months or 500 operating hours whichever comes first for proper operation Should the Versajust slack adjuster not meet the elements of the operational tests noted in this document further investigation and service of the adjuster may be required Every 25 000 miles 3 months or 500 operating hours or at the time of routine vehicle chassis lubrication whichever occurs first the following steps should be followed 1 Visually check for physical damage such as broken air lines and broken or missing parts 2 Lubricate the automatic slack adjuster through the lube fitting with a quality multipurpose chassis lubricant N L G I Grade 2 Lubricate the slack adjuster until clean lubricant flows from the grease relief opening in the boot 3 Perform the n Service Inspection described in this manual IN SERVICE INSPECTION 1 Apply and release the vehicle brakes several times while observing the Bendix Versajust slack adjuster The Versajust slack adjuster and brake actuator should move freely without binding or interference and should return to the full released position Observe the looseness that exists between the yoke and adapter bushing and the yoke and link pins and their mating parts yoke b
21. rts splines on slack or camshaft E Replace weak or broken springs F Repair or replace as required per n Service Inspection G Lubricate test adjuster mechanism conduct in service inspection repair components as necessary replace H Replace or repair as required Damaged Versajust slack adjuster Replace component s or slack adjuster J Correct installation position A Correct the Versajust slack adjuster installation B Loose actuator push rod jam nut B Reposition components and torque to specification C Check spring brake release air pressure and repair or replace air valving as necessary Repair or replace spring brake D Broken foundation brake components D Repair or replace as required per n including camshaft bushings Service Inspection E Check other brakes to ensure they are working Check air pressure balance and threshold pressure refer to Bendix publication BW1555 Check driver braking habits e g use of trailer control valve Use same friction material on all axles F Replace or repair as required G Inspect and correct H New lining swells during break in H Back off adjustment until brakes are free BW7499 2011 Bendix Commercial Vehicle Systems LLC All Rights Reserved 03 11 Printed in U S A
Download Pdf Manuals
Related Search