Automatic Transmission/Transaxle: Description and Operation

DESCRIPTION
General Description



The A340E is a 4-speed, Electronically Controlled Transmission developed for use with high performance engines. A lock-up mechanism is built into the torque converter clutch. The A340E automatic transmission is mainly composed of a torque converter clutch, an Overdrive (hereafter called (O/D) planetary gear unit, a 3-speed planetary gear unit, a hydraulic control system and an electronic control system.

OPERATION
1. OPERATING CONDITIONS





2. FUNCTION OF COMPONENTS











3. HYDRAULIC CONTROL SYSTEM



The hydraulic control system is composed of the oil pump, the valve body, the solenoid valves and the clutches and brakes, as well as the fluid passages which connect all of these components. Based on the hydraulic pressure created by the oil pump, the hydraulic control system governs the hydraulic pressure acting on the torque converter, clutches and brakes in accordance with the vehicle driving conditions.

There are three solenoid valves on the valve body.

- The No. 1 and No.2 solenoid valves are turned on and off by signals from the ECM to operate the shift valves and change the gear shift position.

- The lock-up solenoid valve is operated by signals from the ECM to engage or disengage the lock-up clutch of the torque converter.

4. ELECTRONIC CONTROL SYSTEM



The electronic control system, which controls the shift points and the operation of the lock-up clutch, is composed of the following three parts:

1. Sensors
These sensors sense the vehicle speed, throttle opening and other conditions and transmit these data to the ECM in the form of electrical signals.
2. ECM
The ECM determines the shift and lock-up timing based upon the signals from these sensors, and controls the solenoid valves of the hydraulic control unit accordingly.
3. Actuators
There are three solenoid valves that control hydraulic pressure acting on the hydraulic valves to control shifting and lock-up timing.