- Off-Highway Truck:
- 793D (S/N: FDB1-UP)
- 793C (S/N: ATY1-UP)
ReferenceTesting and Adjusting, SENR1450, "793C and 793C XQ Off-Highway Truck Power Train", "Transmission Hydraulic Control Primary Clutch Pressure - Test and Adjust".
ReferenceTesting and Adjusting, SENR1450, "793C and 793C XQ Off-Highway Truck Power Train", "Transmission Hydraulic Control (Pressure Pack) - Test and Adjust".
ReferenceTesting and Adjusting, RENR8327, "793D Off-Highway Truck Power Train", "Transmission Hydraulic Control Primary Clutch Pressure - Test and Adjust".
ReferenceTesting and Adjusting, RENR8327, "793D Off-Highway Truck Power Train", "Transmission Hydraulic Control (Pressure Pack) - Test and Adjust".
Description of Change:
 | |
| Illustration 1 | g01778014 |
216-2815 Spool | |
The pressure control valve of the ICM transmission hydraulic control is now updated. A new spool assembly is now used in station E of the pressure control valve. The new spool assembly in Station E has a metering notch (1) that helps to prevent dwells in clutch pressure. The metering notch is shown in Illustration 1.
The updated pressure control valve also uses an updated configuration for station D in order to improve the response of main relief pressure. The change in the configuration at station D eliminates oscillations in main relief pressure during shifting of gear by modulating the pressure of station D. When the lockup clutch engages during a reduction in main relief pressure, there may be a slip in the transmission clutches. The updates that are made to the station D reduce the slip in transmission clutches.
The new spool assembly in station E and updates to station D will improve the service life of the friction discs in the transmission.
Adaptable To: The new 216-2815 Spool is a direct replacement for the former 9P-0656 Spool in the control station E of the 339-1285 Pressure Control Valve Gp on the 793C and 793D machines.
When you install the new 216-2815 Spool it is necessary to change the initial pressure setting. The pressure setting must be done during installation of the spool. Refer to Table 1 for initial pressure setting for station E.
Refer to Testing and Adjusting, SENR1450, "793C and 793C XQ Off-Highway Truck Power Train", "Transmission Hydraulic Control Primary Clutch Pressure - Test and Adjust" and Testing and Adjusting, SENR1450, "793C and 793C XQ Off-Highway Truck Power Train", "Transmission Hydraulic Control (Pressure Pack) - Test and Adjust" for the proper procedure to adjust the pressure setting in the transmission pressure control valve group of 793C machines.
Refer to Testing and Adjusting, RENR8327, "793D Off-Highway Truck Power Train", "Transmission Hydraulic Control Primary Clutch Pressure - Test and Adjust" and Testing and Adjusting, RENR8327, "793D Off-Highway Truck Power Train", "Transmission Hydraulic Control (Pressure Pack) - Test and Adjust" for the proper procedure to adjust the pressure setting in the transmission pressure control valve group of 793D machines.
| Initial Pressure Settings for Station E | ||
| Part Number | Description | Pressure Setting |
| 9P-0656 | Spool | 425 kPa (62 psi) |
| 216-2815 | Spool | 440 kPa (64 psi) |
 | |
| Illustration 2 | g01948490 |
339-1285 Pressure Control Valve Gp with updates to station D and station E (2) 216-2815 Spool (3) Station E (4) Station D | |
| Station D Updates | |||||||
| Former Configuration | Action | New Configuration | |||||
| Qty | Part Number | Description | Item | Qty | Part Number | Description | |
| (1) | Addition | 5 | 1 | 9S-8001 | O-ring plug | ||
| 6 | 1 | 4J-7533 | O-ring seal | ||||
| 1 | 5J-1036 | Shim | Replace | 7 | 1 | 8P-9737 | Cascade Orifice |
| 1 | 6T-0094 | Selector Piston | Replace | 8 | 1 | 7G-7431 | Selector Piston |
| 1 | 6T-0093 | Piston | Replace | 9 | 1 | 338-3541 | Piston |
| - | 8H-9190 | Shim (2) | Replace | 10 | - | 4M-1751 | Spacer (3) |
| 8M-2932 | Shim (2) | 11 | 5J-1036 | Shim (2) | |||
| 5J-6153 | Shim (2) | 12 | 5J-2721 | Shim (2) | |||
| 13 | 6J-3993 | Shim (2) | |||||
| 1 | 7M-7316 | Spring | Replace | 14 | 1 | 9W-7411 | Spring |
| 1 | 142-1831 | Stop | Replace | 15 | 1 | 8E-4592 | Stop |
| ( 1 ) | The O-ring plug and the O-ring seal is not used in this location of the former configuration. |
| ( 2 ) | As required, use the shims in order to set the main relief pressure in direct drive. |
| ( 3 ) | As required, use the spacer in order to set the main relief pressure in direct drive. |
| Chart of Shims for Station D | ||||
| Adding shims to station D will increase the station D pressure by the values that are listed. Adding shims to station D will reduce the main relief pressure by the values that are listed. | Part Number for the Shim | Thickness of Shims | The Pressure Change for the Direct Drive Main Relief As A Result Of The Shim | Station D Pressure Change As A Result Of The Shim |
| 5J-2721 | 0.13 mm (0.005 inch) |
15.2 kPa (2.2 psi) |
11.7 kPa (1.7 psi) |
|
| 6J-3993 | 0.25 mm (0.010 inch) |
29.6 kPa (4.3 psi) |
22.6 kPa (3.3 psi) |
|
| 4M-1751 | 0.41 mm (0.016 inch) |
46.9 kPa (6.8 psi) |
36.3 kPa (5.3 psi) |
|
| 5J-1036 | 0.80 mm (0.031 inch) |
94.5 kPa (13.7 psi) |
72.5 kPa (10.5 psi) |
|
Note: Adjust the maximum pressure for station D in order to set the transmission main relief pressure in the direct drive. The transmission main relief pressure (rail pressure) in the direct drive that is measured at the clutch supply rail should be set to 1700 ± 170 kPa (250 ± 25 psi) for all transmissions updated according to this service magazine.
Note: The station D primary pressure must be greater than 207 kPa (30 psi) in order to ensure consistent modulation up to the station D top pressure. To check the station D primary pressure, check the station D pressure with the load piston plug removed.Refer to Table 2 and 3 in order to update the station D of the 339-1285 Pressure Control Valve Gp on the 793C and 793D machines.
The transmission with the serial number prefix 4GX is used on the machines ATY1-UP.
The transmission with the serial number prefix JXG and JGG are used on the machines FDB1-UP.
The updates that are listed above for station E and station D are adaptable to the transmission 4GX1-2176, JGG1-1705 and JXG1-701.
The updates that are listed above for station E and station D are effective in production with the transmission and 4GX2177-UP, JGG1706-UP and JXG702-UP.