STEERING VALVE Caterpillar

Visually-inspect all parts and replace those parts which are not in good condition. The following finished surfaces should be inspected for abnormal wear, scoring or damage.

1. Housing (25) bore and ends.

2. Valve spool (22) outside diameter. Some burnishing due to use may be observed.

3. Valve spool (22) control edges.

4. Valve spool (22) splines.

5. Input shaft (16) seal area. Check for rust, pitting and excessive wear. Light circumferential polishing due to seal contact may be observed.

6. Input shaft (16) helical groove. Note the contact pattern created by the actuator ball (23). Surface should be free from pits chipping or surface break down.

7. Thrust bearing (12) and thrust washers (11) and (13). Inspect for pitting of rolls and faces of thrust washers.

8. Drive link (30) pin slot. Width of slot must not exceed .001 inch difference at any point in its length.

9. Drive link (30) teeth.

10. Torsion bar and needle roller assembly (20). Difference in diameter of needle roller (21) should not exceed .001.

The following parts may show a polish pattern due to the rotor action and the circular motion of the commutator. The sides of these components are ground and lapped and should be free from nicks, burrs and scoring.

1. Spacer (29).

2. Manifold (32).

3. Rotor (31B).

4. Commutator (34). Note: Thickness difference between commutator and commutator ring (33) shall not exceed .0015 inch.

5. End cover and pin assembly (38).

The rotor set (31) requires special attention in handling to avoid nicks and scratching. It is recommended that the rotor (31B), stator (31A), vanes (31D) and springs (31C) be checked in the assembled condition. To inspect the rotor set, place the assembly face down on the lapped face of the end cover (38) and check for freedom of rotor rotation within the stator. The action of the spring loaded vanes may be observed during rotation. The vanes should move freely in their slots, without bind, due to the forces of the springs. (See figure HGA-15).

Figure HGA-15

Using a tapered blade feeler gage, check the rotor (31B) to the stator (31A) clearance as shown in figure HGA-16. If there is more than a .007 inch clearance, the rotor set (31) must be replaced. Note: This applies to rotor sets with and without vanes.

Figure HGA-16

Carefully lift the rotor set assembly (31) from the end cover (38) and measure the thickness of the rotor (31B) and stator (31A). Thickness difference between the rotor and stator shall not exceed .002 inch.

The internal splines in the rotor should not show abnormal wear or damage.