The probable cause may be listed below.
- The wedge assembly is installed incorrectly.
- The power unit is installed incorrectly.
- There is a leak or a restriction in the brake air lines or the valve.
- The air diaphragm is damaged.
- Brakes not adjusted correctly.
- Grease or other contamination is on the brake lining.
- The linings are worn, damaged or missing.
The problem is a braking force that is not equal or the lining wear is not even.
The probable cause may be listed below.
- The air diaphragm is damaged.
- The wedge rod is pulled out of the guide that is on the pushrod of the air chamber.
- The wedge rollers and the cage are pulled out of the slots in the plungers.
- The plungers are corroded or the plungers cannot move freely.
- Brakes not adjusted correctly.
- Grease or other contamination is on the brake lining.
- The quick release valve is worn or damaged.
- The brake shoes are installed backward.
- The drum has a runout of more than 0.25 mm (0.010 inch).
- Wheel bearing not adjusted correctly.
The problem is an automatic adjuster that is not working.
The probable cause may be listed below.
- The pawl is installed backward.
- The pawl cannot move freely in the bore.
- Teeth of the actuator is worn.
- The spring of the pawl is weak or broken.
- The brake actuators are worn or damaged.
- The adjusting bolt cannot move freely in the actuator.
- The detent or the clip that is on shoe retainers are damaged and the adjusting bolt is rotating with the actuator.
- The adjustment plunger is not installed at the leading edge of the shoe.
- The seal of the plunger is damaged or installed incorrectly.
- The shoe retaining springs are weak, damaged, missing or stretched.
- The adjusting bolt is wound too far.
The problem is a parking brake that is not sustaining the brakes.
The probable cause may be listed below.
- The power spring is not fully released.
- The quick release valve is worn or damaged.
- Brakes not adjusted correctly.
- The power spring is weak or broken.
- Grease or other contamination is on the brake lining.
The problem is a brake that is dragging.
The probable cause may be listed below.
- There is not enough air pressure in order to hold the spring brake in the compressed position.
- Brake lines connected to the wrong ports.
- Leaks in brake lines or seals of spring brake.
- Wheel bearings not adjusted correctly.
- The drum has a runout of more than 0.25 mm (0.010 inch).
- The shoe retaining springs are weak, damaged or missing.
- There is a restriction in brake line or the valve does not permit a complete release of the system pressure when the brake pedal is released.
- The plungers are corroded or the plungers cannot retract completely.
- The seal of the plunger is damaged or installed incorrectly.
Hydraulic Cylinder Troubleshooting
The problem is a cylinder rod that creeps.
The probable cause may be listed below.
- There are leaks in the lines or at the connections.
- If a locking valve or a holding valve is not present, there is an internal leak at the control valve.
- There is an internal leakage at the cylinder piston seals.
The problem is a cylinder that is leaking oil.
The probable cause may be listed below.
- There are loose connections or parts.
- The rod seal is damaged.
- The rod is damaged.
- The tube is damaged.
The hydraulic cylinders normally have trouble free operation when the cylinders are properly installed and no dirt is allowed inside the cylinder. A wiper seal is installed in the rod end of the cylinder in order to remove dirt from the rod when the cylinder is retracted.
If the rod was nicked with an extended cylinder, the wiper seal could be damaged by the nick. Dirt can then work by the wiper seal into the cylinder. Dirt inside the cylinder can damage the rod, the piston, the seals and the tube assembly.
Note: Check the rod for nicks or scratches and check the wiper seals for damage. Small nicks can be removed by crocus cloth.
The cause for leaks in the end of the cylinder should be corrected immediately. If tightening of the end cap of the cylinder does not stop leaking, U-cup seals and O-rings should be replaced. The retaining ring can be reused several times.
If the surface of the piston, rod or inside of the barrel (tube) is scratched or damaged, the affected component should be replaced.