CX38–P892 Petroleum Transmission
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| Illustration 1 | g06244874 |
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CX38-P892 (Integrated Pump Drive) (1) Filter inlet pressure coupler (2) Filter outlet pressure switch (3) S.O.S port (4) Output yoke (1810 companion flange shown) (5) Customer interface connector (6) Diagnostic connector (7) Lifting locations (8) Oil filler and dipstick location (9) Outlet To Cooler (SAE J518 Code 61 “-24” flange size) (10) Inlet From Cooler (SAE J518 Code 61 “-24” flange size) (11) Transmission output speed sensors (12) Oil Filter | |
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| Illustration 2 | g06244628 |
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CX38-P892 (SIDE PTO DRIVE) (13) Input from engine flywheel (72 tooth) (14) No. 1 SAE J617 flywheel housing (24 bolts required) (15) Transmission breather (16) Electronic Control Unit (ECU) (17) Clutch 4 pressure test coupler (18) Clutch 5 pressure test coupler (19) Main relief pressure sensor (20) Filter inlet pressure coupler (21) Ecology drain (22) Transmission oil drain plug | |
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| Illustration 3 | g06244914 |
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CX38-P892 (SIDE PTO DRIVE) (23) Magnetic drain plug (24) Lockup clutch pressure coupler (25) Clutch #1 (C1) pressure coupler (26) C2 pressure coupler (27) C3 pressure coupler (28) C6 pressure coupler (29) Torque convertor inlet pressure coupler (30) Transmission lube pressure coupler (31) Torque convertor outlet pressure coupler | |
CX38–P892 Petroleum Transmission With Integral Pump Drives
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| Illustration 4 | g06245276 |
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CX38-P892 (Integral Pump Drive) (1) Filter inlet pressure coupler (S·O·S port) (2) Filter outlet pressure switch (3) Diagnostic connector (4) Customer interface connector (5) Lifting locations (6) Oil filler and dipstick location (7) SAE J615 mounting pads SAE #1 bolt pattern with 6 M16 x 2 threaded holes. SAE #2 width between mounting pads (8) OEM return port (9) Four M16x2 threaded service mounts (10) Transmission output speed sensors (11) Transmission output speed sensors (12) Output yoke (1810 companion flange shown) (13) (S·O·S port) OEM supply port | |
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| Illustration 5 | g06245319 |
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CX38-P892 (Integral Pump Drive) (14) Engine starter ring gear (15) No. 1 SAE J617 flywheel housing (24 bolt) (16) Engine speed sensor (17) Transmission intermediate speed sensor (18) Electronic Control Unit (ECU) (19) Clutch 4 pressure test coupler (20) Clutch 5 pressure test coupler (21) Transmission oil filter pressure sensor (22) Transmission pump pressure coupler (23) OEM PTO oil return (24) Eco drain plug (25) Transmission oil drain plug | |
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| Illustration 6 | g06245323 |
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CX38-P892 (Integral Pump Drive) (25) Magnetic drain plug (26) Lockup clutch pressure coupler (27) Clutch #1 (C1) pressure coupler (28) C2 pressure coupler (29) C3 pressure coupler (30) C6 pressure coupler (31) Torque convertor inlet pressure coupler (32) Transmission lube pressure coupler (33) Torque convertor outlet pressure coupler | |
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| Illustration 7 | g06193776 |
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(C) to Clutch
(P) Supply oil IN (T) to Tank (1) ECPC Valve for Clutch 1 (2) ECPC Valve for Clutch 2 (3) ECPC Valve for Clutch 3 (4) ECPC Valve for Clutch 4 (5) ECPC Valve for Clutch 5 (6) ECPC Valve for Clutch 6 (7) ECPC Valve for the Lock-up Clutch 7 (8) Transmission Hydraulic control manifold (9) Suction screen (10) Oil sump (12) Lubrication Relief Valve (13) Transmission lubrication circuit (13a) Output transfer gear (OTG) lubrication (13b) Flywheel Lubrication (13c) Planetary lubrication (14) Transmission Oil Cooler (15) Torque Converter Temperature Sensor (16) Torque converter (and Lock Up Clutch) (18) T/C inlet relief valve (19) Transmission oil pump (20) Transmission oil filter (21) Main relief valve | |
The "Transmission ECM" controls the operation of the "Electronic Clutch Pressure Control" (ECPC) solenoid valves ( (1) through (7)) for control of the transmission. The ECM uses the transmission clutch proportional solenoid valves in order to shift the transmission. The transmission solenoid valves control the hydraulic circuits that engage the transmission clutch pressures. The ECM supplies electrical current to the appropriate transmission solenoid valves to change the direction and speed of the truck.
The ECM controls the modulation of clutch pressure by sending a variable output current to the appropriate proportional clutch solenoids. The ECM uses input information from the following to determine the correct output current for the solenoids:
- the controls
- the transmission speed sensors
- the transmission temperature sensor
The Transmission ECM will output a pulse width modulated (PWM) signal in order to vary the current to the solenoid. The current to the solenoid determines the amount of pilot oil pressure that is applied to the hydraulic valve spool. The travel of the spool is proportional to the electrical current that is supplied to the solenoid. The position of the valve spool controls the amount of hydraulic oil pressure that is applied to the clutch. The pressure will determine the engagement of clutch. An increase in the electrical output current of the ECM will result in an increase of the engagement pressure of the clutch.
In order to control the shifting of the transmission, the "Transmission ECM" will energize one clutch solenoid when the machine is in PARK or NEUTRAL. The ECM will energize different combinations of clutch solenoids when the machine is in one of the available gears.
| Speed Selection | |||||||
|---|---|---|---|---|---|---|---|
| Clutch 1 | Clutch 2 | Clutch 3 | Clutch 4 | Clutch 5 | Clutch 6 | LUC | |
| 1C | X | X | X | ||||
| 2L | X | X | X | X | |||
| 3L | X | X | X | X | |||
| 4L | X | X | X | X | |||
| 5L | X | X | X | X | |||
| 6L | X | X | X | X | |||
| 7L | X | X | X | X | |||
| 8L | X | X | X | X | |||
| 9L | X | X | X | ||||
| 1RC | X | X | X | ||||
| 2RC | X | X | X | ||||
| N | X | X | |||||
Note: The dropbox transmission has two additional solenoids for engaging and disengaging power from each output yoke.
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| Illustration 8 | g00766511 |
A high current input is made initially. This overcomes the inertia of the valve and the clutch components and this initiates filling of the oil passage leading to the clutch piston. The current is reduced as the clutch piston is filled with oil and the plates move toward engagement. The current is held at a minimum value in order to allow the pressure of the oil in the clutch to increase slowly. The clearances between the plates and the disks are taken up smoothly. This period is called touchup. Once the plates and the disks are in contact, the current is increased gradually in order to ensure that maximum pressure is applied to the clutch in a smooth manner.
Electronic control of this process provides improved quality of transmission shifts.
A combination of clutches engages each of the eight forward gears and reverse gear.