785D OEM Off-Highway Truck Power Train Caterpillar


Transmission Hydraulic Control - Disassemble

Usage:

785D DMC

Disassembly Procedure

Table 1
Required Tools 
Tool  Part Number  Part Description  Qty 
1P-1853  Retaining Ring Pliers 
1P-0510  Driver Group 
156-7100  Puller Group 

Start By:

  1. Remove the transmission hydraulic control. Refer to Disassembly and Assembly, "Transmission Hydraulic Control - Remove".


NOTICE

Keep all parts clean from contaminants.

Contaminants may cause rapid wear and shortened component life.




    Illustration 1g00564027

  1. Mark bolt (3) for installation purposes. Remove bolt (3). Remove five bolts (2), and cover (1) from pressure control valve (4).


    Illustration 2g00564028

  2. Remove pressure control valve (4) from selector and pressure valve (5).


    Illustration 3g00564029

  3. Mark bolt (7) for installation purposes. Remove bolt (7), twelve bolts (6), and selector and pressure valve (5).


    Illustration 4g00564031

  4. Remove bolt (9) and plate (8) from manifold (10).


    Illustration 5g00564073


    NOTICE

    Failure to properly assemble parts or failure to follow established procedures can lead to damage of the parts and assembly.

    To avoid damage to parts, always identify and mark the parts so that they can be installed in the same location. Never force parts during assembly.


  5. Use the following procedure to disassemble stations "A", "B", "C", "E", and "F":

      Note: The pressure control valve for each clutch is marked on the pressure control valve body at location (U). The letter is also stamped on housing (23).

      Note: Station "A" is for the No. 2 clutch. Station "B" is for No. 1 clutch. Station "C" is for No. 3 clutch. Station "E" is for No. 4 clutch. Station "F" is for No. 5 clutch. Station "G" is for No. 6 clutch.

      ------ WARNING! ------

      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 two screws (24) and housing (23) from the pressure control valve body.

    2. Remove spring (15), spring (19), shims (16), piston (17), and piston (18) from housing (23).

    3. Remove spring (20), orifice (21), O-ring seal (22), plug (25), O-ring seal (26), plug (27), O-ring seal (28), plug (29), and O-ring seal (30) from housing (23).

      Note: Plug (27) contains an orifice for most of the stations. Station "G" has a regular plug. The orifice that is in the plugs for the other stations will vary. The orifice sizes may be different. Some plugs also contain a screen.

    4. Remove stop (14), spool (13), and spring (11) from the valve body.

    5. Remove slug (12) from spool (13).


    Illustration 6g00559174


    Illustration 7g00559177

  6. Use the following procedure to disassemble station "D":

      Note: Station "D" is for the signal oil to the dual stage relief valve.

      ------ WARNING! ------

      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 two screws (24) and housing (23) from the pressure control valve body.

    2. Remove the following items from housing (23): spring (11), slug (12), spool (13), stop (14), spring (15), piston (17) and piston (31).


    Illustration 8g00559242

    ------ WARNING! ------

    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. Use the following procedure to disassemble spools (13) of the stations:

    1. Use Tool (A) (not shown) to remove snap ring (35) from spool (13).

    2. Remove retainer (34), spring (33), and ball (32) from spool (13).


    Illustration 9g00559264

  8. Remove bolt (37), washer (38), and piston (36) from the valve body.


    Illustration 10g00559268

    ------ WARNING! ------

    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.


    Note: There is spring pressure against cover (40). Hold the cover while the bolts are removed.

  9. Remove two bolts (39), cover (40), spool assembly (45), and springs (48) and (49) from the valve body.

  10. Remove spacers (46) and (47) from the end of spool (45).

  11. Remove spiral ring (41), retainer (42), spring (43), and check valve (44) from spool (45).


    Illustration 11g00584648


    Illustration 12g00559271

    ------ WARNING! ------

    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.


  12. Remove two bolts (50) and (52) in order to remove the valve body.

  13. Remove O-ring seal (51) and valve (54) from cover (55).

  14. Remove spool (56) and spring (57) from the valve body.

  15. Remove O-ring seal (53) from the valve body.


    Illustration 13g00559275

  16. Use the following procedure to disassemble spool (56):

      ------ WARNING! ------

      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. Use Tool (A) (not shown) to remove snap ring (58) from spool (56).

    2. Remove seat (59), ball (61), and spring (62).

    3. Remove O-ring seal (60) from seat (59).


    Illustration 14g00559277

  17. Remove two bolts (63) and actuator (64).


    Illustration 15g00559280

  18. Remove two bolts (65) and cover (66).


    Illustration 16g00559282

  19. Use Tooling (B) (not shown) to remove bearing (67) from cover (66).


    Illustration 17g00559285

  20. Remove rotor (68) from actuator (64).


    Illustration 18g00559286

  21. Remove two bolts (69) and vane (70) from actuator (64).


    Illustration 19g00559287

  22. Remove plug (71), O-ring seal (72), and valve (73). Remove plug (74), O-ring seal (75), and valve (76). Remove plug (77) and O-ring seal (78) from actuator (64).

  23. Use Tooling (B) (not shown) to remove bearing (79) from actuator (64).


    Illustration 20g00559288

  24. Remove two bolts (80). Remove retainers (83) and springs (81).

  25. Remove bolt (84), washer (85), and rotary selector spool (82).


    Illustration 21g00559289


    Illustration 22g00584701

  26. Remove spring pin (87), cam (86), screen filter (88) and the O-ring seal from rotary selector spool (82).

  27. Remove two spring pins (89) from spring pin (87).


    Illustration 23g00584705

    Note: Mark the location of holes (X) for installation purposes.

  28. If necessary, remove pin (90) and pin (91) from rotary selector spool (82).


    Illustration 24g00559290

    Note: There is a spring under compression in support (92). Hold support (92) when bolts (94) are removed.

    ------ WARNING! ------

    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.


  29. Slowly loosen two bolts (94) in order to release the spring pressure. Remove two bolts (94) and support (92). Remove two dowels (93) from support (92).


    Illustration 25g00559292

  30. Remove spool assembly (95) and spring (97) from the valve body.

  31. Remove shims (96) from spool assembly (95).


    Illustration 26g00559296

    ------ WARNING! ------

    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.


  32. Use Tool (A) (not shown) to remove snap ring (97) from spool (95).

  33. Remove slug (98), spring (99), and ball (100) from spool (95).


    Illustration 27g00559298

    Note: If tubes (102) and (104), and coupler (101) have been removed, proceed to Step 35.

  34. Mark tube (102) and the position on manifold (103). Remove tube (102) and three tubes (104). Remove coupler (101) from manifold (103).


    Illustration 28g00559299

  35. Remove six O-ring seals (106) from three tubes (104). Remove two O-ring seals (105) from tube (102).


    Illustration 29g00559300

  36. Remove retaining ring (107) from coupler (101).


    Illustration 30g00559302

  37. Remove five O-ring seals (111) and O-ring seal (108) from manifold (103).

  38. Remove four plugs (109) and four O-ring seals (110).


    Illustration 31g00559325

  39. Position manifold (103), as shown.

  40. Remove elbow (115) and O-ring seal (116) from manifold (103).

    Note: Mark four bolts (114) and six bolts (113) for installation purposes.

  41. Remove four bolts (114) and six bolts (113) in order to remove cover (112) from manifold (103).


    Illustration 32g00559326

  42. Remove gasket (117) from manifold (103).


    Illustration 33g00559327

  43. Use a small screwdriver to fold the tab. Disconnect wire harness (119) from transmission gear switch (118) of the EPTC II.

  44. Remove two bolts (120) and transmission gear switch (118) from manifold (103).


    Illustration 34g00559328

  45. Remove two bolts (121), cover (122), and wire harness (119) from manifold (103).


    Illustration 35g00559330

  46. Remove O-ring seal (123) from wire harness (119).


    Illustration 36g00559331

  47. Remove three locknuts (124) and the three washers in order to remove three coils (125).


    Illustration 37g00559332

  48. Remove three cartridge assemblies (126) from manifold (103).


    Illustration 38g00559333

  49. Remove two O-ring seals (128) and O-ring seal (127) from cartridge assembly (126). Repeat this procedure on the two remaining cartridges.


    Illustration 39g00559336

  50. Use Tooling (B) to remove lip seal (129) from manifold (103).


    Illustration 40g00559337

  51. Remove dust cap (133) and nipple (132) from manifold (103). Remove plug (134) and five plugs (131) from manifold (103).


    Illustration 41g00559338

  52. Remove O-ring seal (135) from nipple (132).


    Illustration 42g00559339

  53. Remove O-ring seal (136) from each plug (131).

  54. Remove O-ring seal (137) from plug (134).


    Illustration 43g00559340

  55. Use Tooling (C) to remove bearing (138) from manifold (103).


    Illustration 44g00559341

  56. Remove four plugs (139) from manifold (103).


    Illustration 45g00559343

  57. Remove O-ring seals (140) from each plug (139).

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