LINES GP-STICK 1544843 - Caterpillar

Illustration 1 g00997634
Control of the transmission planetary is achieved by hydraulically actuated clutches that hold selected components of the planetary group stationary in order to allow the transmission of drive through the transmission. Oil is supplied by the transmission pump via a filter. The oil (1) is available to each modulating valve (8). The modulating valves control the engagement of particular clutches within the transmission.Shifting of the transmission is controlled by the electronic control module (ECM). The ECM acts in response to a variety of inputs.Inputs to the ECM module include the following information.
Selected Gear
Engine Speed
Ground Speed
High Gear LimitThe control of the transmission also accounts for factors such as the temperature of the transmission oil.Shifting of the transmission gears involves the release of one or more clutches and the subsequent engagement of the next selected clutches.Each clutch is engaged by hydraulic oil pressure that is supplied by the modulating valves. The modulating valves are controlled by pulse width modulated signals (PWM). The signals are sent by the ECM to the individual solenoid (4) on each modulating valve (8) .For details of the operation of the modulating valves, refer to Systems Operation, Testing and Adjusting, "Modulating Valves (Electronic Clutch Pressure Control)".The pressure of the oil in the clutches is approximately proportional to the electrical current that is supplied to solenoid (4) that controls the clutch.
Illustration 2 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 clutch. The current is reduced as the clutch 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 six forward gears and one reverse gear.
Illustration 3 g00761713
Drive to the planetary transmission is through torque converter (12). The torque converter allows the speeds of the engine and the transmission to be matched smoothly. Once the speed of the engine and the transmission is matched, torque converter lockup clutch (11) engages in order to allow direct drive between the engine and the transmission. The torque converter lockup clutch is controlled by the modulating valve (torque converter lockup clutch) (10). The modulating valve for the torque converter lockup clutch is similar to the modulating valves for the planetary transmission clutches.Oil is supplied to the torque converter by relief valve (17). Oil from the torque converter flows to the retarder hydraulic control valve (13) through torque converter outlet relief valve (15). The torque converter outlet relief valve maintains a required pressure in the torque converter.From the retarder hydraulic