Slack Adjuster Replacement, Service Tests

SLACK ADJUSTERS MOUNTED IN TENSION OR COMPRESSION

	BRAKE	BRAKE
	CHAMBER	CHAMBER
	SLACK	SLACK
	ADJUSTER	ADJUSTER
	ADJUSTING	ADJUSTING
	ADJUSTING	SCREW
	SCREW	SCREW
	SCREW
	TENSION	COMPRESSION

PROVIDED THE MAXIMUM TORQUE RATING IS NOT EXCEEDED, BENDIX SLACKS CAN BE MOUNTED IN EITHER DIRECTION AND STILL MEET THE ENGINEERING TEST SPECIFICATION (50K CYCLES AT MAXIMUM RATED LOAD). COMPRESSION MOUNTING IS RECOMMENDED AND WILL YIELD A LONGER SERVICE LIFE.

NOTE: Some Bendix slack adjusters were manufactured without a lubrication provision in the body; however, the slack adjuster may be lubricated through the cover as follows:

1.Remove rubber plugs from both covers and discard.

2.Determine which side of slack adjuster is accessible for lubrication and install washer (Pc. No. 230156) and grease fitting (BW Pc. No. 244017) Alemite #1625 using Alemite tool #5254 to press grease fitting firmly in place in cover.

3.Install steel plug (Pc. No. 244400) in other cover, making certain it is firmly in place.

4.Lubricate slack adjuster. Apply a sufficient amount of grease to completely fill body cavity.

SERVICE TESTS

1.Apply brakes and check that slack adjusters rotate freely and without binding.

2.Release brakes and check that slack adjusters return to the released position without binding.

3.With brakes released, check that the angle formed by the slack adjuster arm and actuator push rod is greater than 90 degrees. All slack adjusters should be set at this same angle.

4.With brakes applied, check that the angle formed by the slack adjuster arm and actuator push rod is still slightly greater than 90 degrees. All slack adjusters should be set at this same angle.

REMOVAL AND INSTALLATION

CAUTION: Before attempting to remove slack adjusters, proper precautions should be taken so that an automatic application of the actuators does not occur while removing or installing slack adjusters, thus causing possible injury. Decreasing air pressure can cause a sudden full brake application without warning. Depending on type of system on vehicle, it maybe necessary to drain all air reservoirs or mechanically back off spring brake chambers.

A. REMOVAL

1.Remove the chamber push rod yoke pin.

2.Remove the retaining mechanism from end of brake cam shaft.

3.Rotate the slack adjuster by turning the adjusting nut.

4.Slide the slack adjuster off of the spline end of the brake cam shaft.

B. INSTALLATION

1.Install slack adjuster on brake cam shaft so the adjustment screw and grease fitting (if so equipped) are accessible for servicing.

2.Install retaining mechanism on end of brake cam shaft to hold slack adjuster in place.

3.Turn adjusting nut to line up yoke pin hole with arm hole. Install yoke pin and cotter pin.

4.Refer to steps 3 and 4 under “Service Tests” and make sure the proper adjustments are made after installing a slack adjuster.

SLACK ADJUSTER REPLACEMENT

When replacing one type of slack adjuster with another type, it is necessary to match or exceed the torque rating and match the arm length, yoke pin diameter, offset spline diameter and width. It is also necessary to make certain that there is adequate clearance at release and full stroke.

DISASSEMBLY AND ASSEMBLY

NOTE: Disassembly and assembly instructions apply only to assemblies with riveted covers. Assemblies with welded covers are considered non-serviceable and are replaced as an assembly.

TYPE 20 TO 30 WITH POSITIVE LOCK MECHANISM AND RIVETED COVER DISASSEMBLY

1.Remove rivets holding covers.

2.Remove welch plug.