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| Illustration 1 | g02677840 |
Block Diagram for the Transmission System (1) Charge pump (2) Filter (3) Auto switch (4) Shift lever (5) Inching pedal (6) "CAN" Data Link (7) Transmission ECM (8) Relief valve (9) Oil cooler (10) Transmission (11) Modulating valves (12) Sump | |
The operator can initiate a hydraulic function by using one of the following controls:
- Auto shift switch (3)
- Shift lever (4)
- Inching pedal (5)
The controls will send a signal to the transmission electronic control module (ECM) (7). The transmission ECM will then process these signals.
The transmission ECM will energize modulating valve (transmission) (11) .
Sump (12) is located in the transmission case. Sump (12) supplies charge pump (1) with oil. The oil goes through filter (2). The oil is then delivered to relief valve (8) (charge pressure). The relief valve controls the oil pressure to 2482.1 kPa (360 psi). All excess oil is routed through oil cooler (9). The oil then goes to the transmission lubrication circuit.
Transmission Electrical Control System
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| Illustration 2 | g02678936 |
Electrical Block Diagram for the Transmission System (3) Auto shift switch (7) Transmission ECM (12) Dash panel display (13) CAT data link (14) Service connector (15) Charge pressure sensor (16) Hydraulic oil temperature sensor (17) Output speed sensors (18) Input speed sensor (19) Inching pedal position sensor (20) Inching pedal switch (21) Shift lever position sensor (22) Modulating valve (Transmission clutch (H) NO.1) (23) Modulating valve (Transmission clutch (J) NO.2) (24) Modulating valve (Transmission clutch (C) NO.3) (25) Modulating valve (Transmission clutch (B) NO.4) (26) Modulating valve (Transmission clutch (D) NO.5) (27) Modulating valve (Transmission clutch (G) NO.6) (28) Modulating valve (Transmission clutch (E) NO.7) (29) Modulating valve (Transmission clutch (F) NO.8) (30) Modulating valve (Transmission clutch (A) NO.9) (31) CAN data link (32) Service connector | |
The electrical system for the transmission consists of the following components:
- Switch (auto shift) (3)
- Transmission ECM (electronic control module) (7)
- Dash panel cluster (12)
- CAT data link (13)
- Service connector (14)
- Pressure sensor (charge) (15)
- Temperature sensor (hydraulic oil) (16)
- Speed sensor (transmission output) (17)
- Speed sensor (transmission input) (18)
- Position sensor (inching pedal) (19)
- Switch (inching pedal) (20)
- Position sensor (shift lever) (21)
- Modulating valve (transmission clutches No. 1 - No. 9) (22 through 30)
- CAN data link (31)
- Service connector (32)
The Transmission ECM (6) controls solenoid valve (22) through solenoid valve (30) for the transmission.
CAT data link (13) is a serial communication bus that is used in order to communicate with the following component:
- Caterpillar electronic technician (ET)
CAN data link (31) is a serial communication bus that is used in order to communicate with the following components:
- Engine ECM
- Transmission ECM
- Dash panel cluster
- Other OEM electronic control modules
Shift lever (21) sends a PWM signal to transmission ECM (7) via the CAN data link (31). Transmission ECM (7) processes the signal in order to determine the position of the lever.
Speed sensors (17), temperature sensor (16), and pressure sensor (15) send signals to transmission ECM (7). The transmission ECM uses the signals in order to monitor the conditions of the transmission.
Transmission Hydraulic System
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| Illustration 3 | g02730898 |
Block Diagram for the Transmission Hydraulic System (1) Charge pump (2) Filter (8) Main relief valve (9) Oil cooler (10) Transmission (11) Modulating valves (12) Sump (33) Suction screen (34) Cooler bypass valve (35) Lube relief valve | |
Oil from sump (12) is drawn through suction screen (33) by the charge pump (1). Suction screen (33) is rated at 200 micron. Hydraulic oil filter (2) filters the oil from charge pump (1) .
Filtered oil is supplied to following valves:
- Modulating valves (transmission) (11)
- Relief valve (8)
When the modulating valves are energized, oil flows to the transmission clutches. When the modulating valves are de-energized, oil flows from the valve to the sump.
The relief valve (charge pressure) regulates the pressure in the transmission hydraulic system to a maximum pressure of 2482 kPa (360 psi).
Excess oil flows from relief valve (8) (charge pressure) to hydraulic oil cooler (9). Cooler bypass valve (34) will open if a pressure of 520 kPa (75 psi) is felt at the input side of the hydraulic oil cooler. Normally, the cooler bypass valve will remain closed unless there is a restriction in the hydraulic oil cooler or if the oil is cold.
Oil from hydraulic oil cooler (9) flows to the transmission for lubrication. Transmission lubrication relief valve (35) regulates the oil pressure for lubrication to 275 kPa (40 psi).