The brake valve is a reliable hydraulic valve with internal components manufactured to close tolerances. Due to the close tolerances and mating of components, the valve housing, spool, piston and check poppet bare not available as replacement parts.
Before disassembling the brake valve, be sure you have conducted all applicable troubleshooting operations and are certain the brake valve is causing the malfunction.
Thoroughly clean the outside surfaces of the valve and work in a clean dust free area, as cleanliness is of utmost importance when servicing hydraulic components.
Disassembly
1. Remove the pilot orifice (9) from the brake release (BR) port using a 5/32 in. Allen wrench.
2. Remove the plug (19) from the drain port.
3. Remove the spool spring retainer (3) and spool spring (11). Check spring free length. Replace spring if less than 2 1/2 inches (63.5 mm) long.
4. Remove spool plug (4) and carefully remove spool (5).
5. Remove the check valve spring retainer (2), spring (10) an d check valve poppet (8). Check spring free length. Replace spring if less than 1-1/2 in. (38.1mm) long.
Clean and Inspect
1. Discard all O-rings and back-up rings. Clean all parts in solvent and blow dry. Inspect polished surfaces of spool for damage that may cause binding or leakage. Inspect spool bore in valve housing for damage or scoring. Inspect check valve seat in valve housing and check valve poppet. If the spools, bore or valves are damaged, the entire valve must be replaced as these parts are not serviced separately.
2. Inspect the .020 inch orifice in the pilot orifice (9) to be certain it is open.
Assembly
1. Install new O-rings on the plug and spring retainers.
2. Install new O-rings and back-up rings on the spool. It is important that the back-up ring is on the correct side of its O-ring. Take care not to cut the O-ring during assembly. Let the spool set for ten minutes before installing them in their respective bores. This will allow the O-ring to return to their original size after being stretched.
3. Lubricate the spool bore and spool O-rings with hydraulic oil. Carefully install the spool into the valve housing. Always install the spool from the end as shown to minimize the possibility of damaging the O-ring. Install the plug, spool spring and spring retainer.
4 Install the check valve poppet, spring, and check valve spring retainer
5. Install the solid plug into the "drain" port.
6. Install the pilot orifice into the valve housing.
7. The brake valve is complete and ready to be installed on winch motor.