Spool Will Not Return To Neutral

HYDRAULIC

TROUBLESHOOTING

CAUSE

REMEDY

Unable To Push Spool In

1. Refer to "Oil Leaks At Either Spool End".

1. Oil leaking into cap

Spool Will Not Return To Neutral

1. Replace springs.

1. Weak or broken spring

2. Replace valve spool. Check valve body bore.

2. Bent valve spool

Replace the assembly if bore is defective.

3. Refer to "Oil Leak At Either Spool End".

3. Oil leaking into cap

Disassemble, clean and inspect valve parts.

Replace parts as necessary.

4. Foreign particles lodged between spool and bore

5. Lubricate, straighten, free-up linkage as necessary,

5. Sticking linkage

No Motion - Slow Or Jerky Action

1. Remove and check the pilot valve and regulating

valve. Replace parts as necessary. Replace valve

1. Regulating valve not operating properly

assembly if the bore is defective.

2. Disassemble the control valve assembly and clean

thoroughly.

2. Dirt lodged between regulating valve and bore or

3. Check for broken, bent or worn springs.

Replace

between pilot valve and seat

springs as necessary.

3. Defective pilot valve spring or regulating valve spring

4. Replace the O-ring. Check the pilot valve for ridges at

the seating area.

4. Defective O-ring on the regulating valve

5. Replace valve assembly.

5. Internal crack in valve body

6. Check and repair linkage. Check valve spool, bore

and oil seal on cap end, Replace parts as necessary.

6. Spool not moving the full stroke

1. Clean, inspect and replace parts as necessary,

Load Will Not Hold

1. Check valve not seating

B-157