621H, 623H and 627H Wheel Tractor-Scrapers Machine Systems Caterpillar

Disassembly Procedure

Start By:

1. Remove the steering control valve.

Note: Place identification marks on the steering control valve for assembly purposes.

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Illustration 1	g01035491

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Personal injury can result from being struck by parts propelled by a released spring force. Make sure to wear all necessary protective equipment. Follow the recommended procedure and use all recommended tooling to release the spring force.

1. Remove plug (2), spring (3), and strainer (4) from steering control valve (1).
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   Illustration 2	g01160560

2. Remove check and relief valve (5) and the O-ring seals from steering control valve (1).
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   Illustration 3	g01035494

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   Personal injury can result from being struck by parts propelled by a released spring force. Make sure to wear all necessary protective equipment. Follow the recommended procedure and use all recommended tooling to release the spring force.

3. Remove plugs (7), the O-ring seals, springs (8), and check balls (9) from check and relief valve (5). Remove plug (6) and the O-ring seal from check and relief valve (5). Remove valves (10), the rings, and the O-ring seals from check and relief valve (5).
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   Illustration 4	g01035496

4. Remove check valves (11) and (12) from check and relief valve (5).
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   Illustration 5	g01035498

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   Personal injury can result from being struck by parts propelled by a released spring force. Make sure to wear all necessary protective equipment. Follow the recommended procedure and use all recommended tooling to release the spring force.

5. Use Tooling (A) to remove retaining ring (13) from check valve (12). Remove spacer (18), spring (14), and check ball (19) from check valve (12). Remove plug (17) and O-ring seal (21) from check valve (12). Remove stem (16) and the O-ring seal from check valve (12). Remove O-ring seals (20) and O-ring seal (15) from check valve (12).

6. Repeat Step 5 for check valve (11).
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   Illustration 6	g01035499

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   Illustration 7	g01035500

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   Personal injury can result from being struck by parts propelled by a released spring force. Make sure to wear all necessary protective equipment. Follow the recommended procedure and use all recommended tooling to release the spring force.

7. Remove nut (28), retainer assembly (27), O-ring seal (26), spacer (25), spring (24), and poppet (23) from cover (22).
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   Illustration 8	g01035501

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   Personal injury can result from being struck by parts propelled by a released spring force. Make sure to wear all necessary protective equipment. Follow the recommended procedure and use all recommended tooling to release the spring force.

8. Remove bolts (29) and cover (22) from steering control valve (1).
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   Illustration 9	g01035502

9. Remove valve (30) from cover (22). Remove O-ring seal (31) from valve (30). Remove O-ring seals (32) from cover (22).
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   Illustration 10	g01035503

10. Remove springs (35), shims (34), and valve (33) from steering control valve (1). Remove valve (36) from steering control valve (1). Remove spool valve (37) from steering control valve (1).
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    Illustration 11	g01035505

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    Personal injury can result from being struck by parts propelled by a released spring force. Make sure to wear all necessary protective equipment. Follow the recommended procedure and use all recommended tooling to release the spring force.

11. Slowly remove bolt (40) and the washer from spool valve (37). Remove retainer (43), spring (39), washer (42), retainer (38), and shims (41) from spool valve (37).
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    Illustration 12	g01035506

12. Remove plugs (44) and the O-ring seals from spool valve (37).
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    Illustration 13	g01035508

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    Personal injury can result from being struck by parts propelled by a released spring force. Make sure to wear all necessary protective equipment. Follow the recommended procedure and use all recommended tooling to release the spring force.

13. Remove plug (45) and the O-ring seal from cover (49). Remove shims (46), spring (47), and stem (48) from cover (49).
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    Illustration 14	g01035509

14. Remove bolts (50) and cover (49) from steering control valve (1).
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    Illustration 15	g01035511

15. Remove valve (51) and spacer (54) from steering control valve (1). Remove O-ring seals (52) from valve (51). Remove O-ring seal (53) from spacer (54).
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    Illustration 16	g01035512

16. Remove plug (55) and the O-ring seal from valve (51).