Operation and maintenance manual

Section 230-0121
Body System - Pilot Supply Valve
2
SM 1448 Rev 1 1-02
REMOVAL
Numbers in parentheses refer to Fig. 1.
WARNING
To prevent personal injury and property
damage, be sure wheel blocks, blocking
materials and lifting equipment are properly
secured and of adequate capacity to do the job
safely.
1. Position the vehicle in a level work area, apply the
parking brake and switch off the engine. Operate
steering right and left several times to relieve pressure
in the steering system. Operate treadle valve
continuously to relieve pressure in the braking system.
2. Block all road wheels and place the battery master
switch in the 'Off' position.
3. Remove blanking cap from remote drain line at the
bottom of the hydraulic tank. Install a length of hose on
remote drain fitting, open drain cock and drain hydraulic
oil into a suitable container. Close drain cock, remove
hose and reinstall blanking cap.
4. Clean pilot valve (1) and surrounding area with a
suitable solvent. Identify and tag all hydraulic lines
connected to pilot valve (1), to aid in 'Installation'.
5. Clean pilot valve (1) and surrounding area with a
suitable solvent. Ensure all hydraulic lines connected
to pilot valve (1) are identified for ease of installation
and, with suitable containers available to catch
leakage, disconnect hydraulic lines. Fit blanking caps
to all open lines.
6. Remove bolts (27) and lockwashers (28) securing pilot
valve (1) to cradle assembly. Remove pilot valve (1).
DISASSEMBLY
Numbers in parentheses refer to Fig. 1.
1. Note location of elbows (24), Tee piece (25) and
adaptors (23) and remove from valve body (1) and
reducer (22).
2. Remove reducer (22) and 'O' ring (21) from valve
body (1). Discard 'O' ring (21).
3. Remove plug (7) and 'O' ring (8) from valve body (1).
Remove valve seat (9), 'O' ring (10) and spacer (11)
from valve body (1). Discard 'O' rings (8 & 10).
4. Remove adaptor (18) and 'O' ring (17) from valve
body (1). Discard 'O' ring (17). If necessary remove
plug (19) from adaptor (18).
5. Remove spring guide (15) and 'O' ring (14) from
valve body (1). Discard 'O' ring (14).
6. Withdraw spring (13) and pilot (12) from valve body (1).
7. Remove spring cover (2) and 'O' ring (3) from valve
body (1). Discard 'O' ring (3).
8. Withdraw control spring (4), spring guide (5) and
control spool (6) from valve body (1).
INSPECTION
Numbers in parentheses refer to Fig. 1.
1. Clean all parts with a suitable solvent and dry with
compressed air.
2. Check ports threads and make sure they are not
damaged or stripped.
3. Check valve seat (9), pilot (12), control spool (6) and
spring guide (5). Ensure they are not worn, nicked,
cracked or scored.