STEERING VALVE Caterpillar

IMPORTANT: Before starting assembly, clean all parts with clean petroleum base solvent and air dry. Do not wipe dry with rags. Be sure all dried paint lips have been removed from edges of lapped surfaces. Unless otherwise indicated, DO NOT oil parts before assembly.

1. Insert ball (26) into its cavity in the housing.

2. Install new "o" ring (27) on plug and roll-pin assembly (28) and install in the housing (25) to 10-14 ft. lbs. torque.

3. Reclamp housing (25) in the vise as shown in figure HGA-11.

4. Assemble thrust washer (13) thrust bearing (12) thrust washer (11) and retaining ring (10) on input shaft (16).

5. If the retaining spring (24) has been removed, install a new retaining spring.

6. Insert actuator ball (23) into ball seat located inside spool (22).

7. Assemble wave spring washer (14) over thrust washer (13) and thrust bearing (12). Insert the input shaft (16) into the spool, engaging the helix and ball with a counter-clockwise motion. This operation is best done while holding the spool in a horizontal position.

8. Using the mid-section of the torsion bar (20) as a gage, insert the gage between the spool end and the thrust washer (13). (See figure HGA-17). This will position the spool in the necessary radial relationship with the input shaft spline teeth for assembly of drive ring (18).

Figure HGA-17

9. Place the input shaft (16) and spool (22) assembly in a vertical position, with the shaft end on the table surface.

10. Insert the drive ring (18) into the spool (22) end by visually aligning an internal space on the drive ring with a tooth on the input shaft (16) spline, and allow the drive ring to drop to the limit of its travel. If the drive ring does not engage the input shaft spline, a slight rotation of the input shaft will allow the drive ring to become fully engaged. Remove torsion bar (20) gage. (See figure HGA-18).

Figure HGA-18

11. Install spacer (19) over torsion bar and pin assembly (20) and insert the assembly into the spool (22) end.

12. Align the cross-hole in the torsion bar (20) with the cross-hole in the input shaft (16) and insert a .120 diameter pin punch to maintain alignment.

13. Insert the needle roller (17) into cross-hole in input shaft (16); and while retracting the pin punch, engage the pin in the torsion bar (20) cross-hole.

14. Initiate press of needle roller (17) into torsion bar (20) with a few light impacts. Press needle roller flush with outside diameter of input shaft (16) using a 1/2" drive socket of 11/16 size for supporting the input shaft. (See figure HGA-19). With a few light impacts on .120 diameter pin punch, drive needle roller (17) approximately 1/32 below the input shaft (16) O.D. (See figure HGA-12).

Figure HGA-19

15. Assemble spacer (15) over valve spool (22), against spring washer (14). If so constructed, the inside lip end of spacer must be toward the spring washer. Place assembly, spool end first, into housing (25). Caution: Avoid applying side forces to the spool which would cause binding of the closely fitted assembly.

16. a.

NOTE: If neither the input shaft (16) or upper cover (7) are replaced, the original shims (9) may be reused. However, if in the inspection of parts, damage is found to the shims, discard these shims and replace with new parts of equal thickness.

Place shims on tip of the thrust washer (11). Coat "o" ring (8) with clean grease and place in upper cover (7) counterbore. Assemble upper cover onto input shaft (16) and rotate to align punch marks previously made during disassembly. Note: If a new upper cover is used no angular orientation is required. However, it is necessary to align the upper cover and housing (25). Replace screws finger tight and then use a pilot ring or a worm drive type hose clamp tightened around the upper cover flange and the body pilot diameter to achieve the required alignment. Now tighten screws to 18-22 ft. lbs. torque. (See figure HGA-20).

Figure HGA-20

16. b.

NOTE: If either the input shaft (16) or upper cover (7) or both have been replaced, the following procedure for shimming must be used. Re-assemble as in "a" above using the required new parts. After torquing the four screws (6) revolve unit in vise so that the input shaft is pointing downward. In order to determine that the unit is shimmed correctly, the drive link (30) must be in its proper position. To do this, grasp the input shaft (16), pull downward, and prevent rotation. Engage drive link splines in spool (22) and rotate to position spool essentially flush with end of housing (25). Remove drive link and orient drive link slot to engage torsion bar needle roller (21) and insert drive link. Observe relationship of spool end to body. If this is within .0025 of being flush, no additional shimming is required. If not within .0025, add or remove shims (9) until this requirement is satisfied repeating assembly steps as outlined in "a" above. (See figure HGA-21).

Figure HGA-21

16. c. The correct shimming must be checked on the vehicle or on a suitable hydraulic test stand. The amount of steering effort required to steer the vehicle when the vehicle is at rest on dry pavement must be equal within two inch pounds. For example, if fifteen inch pounds is required to steer to the right, not less than thirteen or more than seventeen inch pounds should be required to steer to the left.

If a test stand is available to place a load between cylinder ports in the same manner as on the vehicle, a test stand my be used. Add shims to increase steering efforts in a left turn, subtract shims to increase steering effort in a right turn.

17. With the drive link (30) installed as described above, assemble two assembly posts into the housing (25) as shown in figure HGA-22. These assembly posts can be made by simply cutting the heads off of two bolts similar to the special bolts. (39).

Figure HGA-22

18. Assemble spacer plate (29) over assembly posts and onto housing (25) with plain side up. (See figure HGA-23).

Figure HGA-23

19. Install rotor set (31) over assembly posts and onto spacer plate (29). Note: One of the seven holes in the rotor set may be smaller than the other six holes. Position this hole, if applicable, over one of the assembly posts. (See figure HGA-24). Warning: All vane springs (31C) must be down in their slots with no part of spring proturding out either side of metering element.

Figure HGA-24

20. Install manifold (32) over assembly posts and onto rotor set (31), make sure circular slot side of manifold is up. (See figure HGA-25).

Figure HGA-25

21. Install commutator ring (33) over assembly posts and onto manifold (32), make sure slot side is down. (See figure HGA-26).

Figure HGA-26

22. Install rotor seal (36) and seal retainer (35) over rotor set (31) and down against housing.

23. With counterbore side of commutator (34) up assemble commutator (34) into commutator ring (33) with slotted hole in commutator engaging nose of drive link (30). Align commutator outside diameter concentric with inside diameter of commutator ring. (See figure HGA-27).

Figure HGA-27

24. Apply a small amount of clean grease to washer (37) and install over pin in end cover assembly (38). Grease should hold washer (37) to end cover assembly.

25. Assemble end cover assembly (38) with washer (37) attached over assembly posts and onto HGA unit.

26. Install five of the special bolts (39) finger tight. Remove two assembly posts and assemble the other two special bolts (39) finger tight. Warning: Finish tighening the seven special bolts per steps 1 and 2 as follows, and do not over torque as it will cause unrepairable damage:

1. Torque all seven special bolts to 2-3 ft. lbs. in sequence as shown in figure HGA-28.

2. Torque all seven special bolts to 15-19 ft. lbs. in sequence as shown in figure HGA-28.

Figure HGA-28

27. Relocate HGA unit in a vise with the input shaft up. Cover end of input shaft with cellophane tape, to protect new seal (5) when it is assembled over sharp edges of input shaft.

28. Lubricate and install new seal (5) with lip side first onto input shaft.

29. Assemble new washer (4), with small end first, onto input shaft and push new washer and new seal down into upper cover (7). (A short piece of metal tubing, 15/16" minimum I.D. x 1-3/16" maximum O.D. or a 7/8" deep well socket may be used to push these parts into place.)

30. Assemble retaining ring (3) into upper cover (7) groove. Be sure rounded edge of retaining ring is faced inward.

31. Assemble new dirt seal (2) into upper cover (7) counterbore.

32.

NOTE: If the HGA unit is to be stored, plug the cylinder ports and fill the inlet port with clean oil. Rotate input shaft until oil appears at outlet port.

33. Plug the port holes to prevent entrance of dirt. This completes assembly of the HGA unit.

To Disassemble Column

1. Remove steering wheel and wheel nut (8).

2. Loosen clamp assembly (1) on upper cover of HGA unit. If the application has a column support clamp, this clamp should be loosened at this time.

3. If there is a horn contact assembly on the column, remove the 4 small screws from the metal cover (if applicable), and remove the metal cover and gasket. Remove the 2 small screws from the horn contact assembly.

4. Pull the jacket tube (6) and bearing assembly (7) off of the wheel tube (5).

5. Remove the retaining springs (3).

6. Lightly tap out the pins (4) with brass rod and hammer. Do not hit the pins with heavy hammer blows, as this may damage the needle bearing in the HGA unit.

7. Remove the wheel tube (5).

8. Remove the coupling (2).

9. Remove the clamp assembly (1).

To Assemble Column

1. Assemble the clamp assembly (1) onto the HGA unit. (Do not tighten).

2. Assemble the coupling (2) and align pin hole.

3. Assemble one of the pins (4) and one of the retaining rings (3).

4. Assemble the wheel tube (5) and align pin hole.

5. Assemble the other pin (4) and retaining ring (3).

6. Apply a small amount of clean grease to the inside of bearing assembly (7).

7. Assemble the jacket tube (6) and bearing assembly (7) over the wheel tube, through the clamp assembly (1) and onto the HGA unit upper cover.

8. Tighten the clamp assembly (1) bolt to 15-20 ft. lbs.

9. Assemble the steering wheel and tighten the wheel nut to 32.5 - 37.5 ft. lbs.

10. If the application has a column support clamp, is extremely important that the jacket tube (6) align with this clamp in the free state. If misalignment is evident, the HGA unit must be shimmed at the mounting surface to eliminate the misalignment, or damage may result to the HGA unit.

11. If applicable, assemble the horn contact assembly, cover gasket and metal cover on the jacket tube (6).