TRACK ROLLER ASSY. 3A9550 - Caterpillar

Illustration 1 g02150157
Schematic of the Power Train/Chassis Electronic Control ModuleThe Power Train/Chassis Electronic Control Module (ECM) controls all of the system features for the transmission. A general description of each transmission feature is listed below:Harness Code - The harness code is from the Caterpillar Monitoring System. The strategy for shifting is different on the machines. The Caterpillar Monitoring System must know the model that the system is on in order to operate correctly. This information is provided to the Caterpillar Monitoring System by the status of the inputs to the monitoring panel. The permanent connections in the machine harness provide this information.Shift Lever Position Sensor - The shift lever position sensor sends a signal to the Power Train/Chassis ECM. The Power Train/Chassis ECM determines which transmission hydraulic clutches are applied in order to formulate the requested gear.Transmission Output Speed Sensor - The Power Train/Chassis ECM uses information from the transmission output speed sensors in order to allow the transmission to shift as ground speed changes. The speed sensors are also used to diagnose each other during normal operation. The Power Train/Chassis ECM periodically checks the value from the speed sensors. If an incorrect value is found, the Power Train/chassis ECM will log a service code that indicates a fault for a speed sensor circuit.Transmission Hydraulic Control Modulating Valve - The Power Train/Chassis ECM electrically shifts the transmission. The Power Train/Chassis ECM uses seven separate outputs to the transmission hydraulic control modulating valves in order to shift the transmission. Two modulating valves must be energized for drive to be transmitted from the transmission. The transmission is always shifted one gear at a time.When the operator selects a forward gear the Power Train/Chassis ECM automatically shifts the transmission. The shift is dictated by the transmission output speed. The automatic shift points are stored in the Power Train/Chassis ECM. A shift occurs when the transmission output speed matches the shift point. When the transmission output speed increases to a shift point the Power Train/Chassis ECM energizes the correct transmission hydraulic control modulating valves.Note: The transmission output speed is directly proportional to ground speed and engine speed. This occurs while the transmission is in direct drive. Shift points are based on the calculated engine speed.The items that follow are exceptions.
If a shift from a forward gear or reverse gear to NEUTRAL is made and the machine is moving faster than 5 km/h (3.1 mph), the Power Train/Chassis ECM will not shift the transmission into neutral until the ground speed is less than 5 km/h (3.1 mph). This feature discourages coasting in neutral at high speed, which reduces transmission life. For more information, see the topic in System Operation, Troubleshooting, Testing, and Adjusting, "Neutral Coast Function".
The reverse gear is not engaged until ground speed is less than 5 km/h (3.1 mph). This feature helps protect the transmission from damaging directional shifts.
The Power Train/Chassis ECM does not downshift when the operator selects a speed that is not appropriate for the current transmission output speed sensor.