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| Illustration 1 | g00691039 |
Schematic for the power train electronic control (1) Parking brake switch (2) Tiller for the differential steering (3) Cat data link (4) Electronic control module (ECM) (5) CMS (monitoring system) (6) Connector (7) Connector (8) Service tool (9) Steering differential and brake on the left side of the machine (10) Planetary gears and brake on the right side of the machine (11) Brake control valve (12) Transmission modulating valves and the main relief valve (13) Priority valve (14) Brake pedal (A) Output speed of the torque converter (B) Intermediate speed of the transmission (C) Output speed of the transmission (D) Engine speed (E) Oil temperature | |
Reference: Refer to Service Manual, SENR8367, "Power Train Electronic Control System" for system operation, testing and adjusting procedures.
The electronic control system for the power train performs two main functions:
- Shifting of the transmission
- Braking
The electronic control system for the power train also performs the following functions:
- Parking brake function
- Neutral start
- Warning function
- Backup alarm
Shifting of the Transmission
The electronic control system for the power train performs the shifting of the transmission. Electronic control module (4) responds to the request for shifting. ECM (4) controls the electrical current of the modulating valves for the transmission. The current to the valve solenoids controls the oil pressure that engages the transmission clutches.
The electronic control system for the clutch pressure controls the transmission clutch engagement.
Electronic Clutch Pressure Control (ECPC)
The ECPC is used with the power train electronic control system. Electronic control module (4) selects the transmission clutches that will be engaged. The clutch pressure is modulated electronically. Solenoid valves control the modulation of the clutch pressure. Electronic control module (4) uses signals from the transmission speed, the engine speed and the power train oil temperature. These signals are used to control the smooth engagement of the clutches.
Each transmission clutch has a corresponding solenoid valve. Electronic control module (4) uses the transmission valves to modulate the oil pressure to each transmission clutch. The solenoid valves operate in a proportional manner. Electronic control module (4) modulates the current of the solenoids.
Modulating the solenoid valves controls the power train oil flow to the transmission clutches. First, the operator requests a transmission shift. Electronic control module (4) selects the appropriate transmission clutches for engaging. The ECM also controls the rate of the modulation of the clutch pressure.
Braking
Braking is controlled by the electronic control system for the power train. The brakes are applied with springs. The brakes are released hydraulically.
Service brake pedal (14) and parking brake switch (2) inform ECM (4) of the requests for braking. The ECM removes the current from the solenoid valve on brake control valve (11). When braking is not requested, the solenoid valve receives current. The valve opens and the brakes are hydraulically released.