MOTOR AS-BLOWER 1741505 - Caterpillar

Hydraulic Components
Illustration 1 g01659034
(1) Transmission output speed sensor
(2) Clutch pressure test ports
(3) Torque converter inlet relief valve
(4) Transmission hydraulic control relief valve
(5) Planetary lubrication relief valve
(6) Torque converter lock up clutch valve
(7) Power train gear pump Control of the transmission planetary is achieved by hydraulically actuated clutches that hold selected components of the planetary group stationary. Holding selected components allows transition of power in the selected gear (speed ratio) through the transmission.Transmission Hydraulic System
Illustration 2 g01345503
(8) Pressurized oil
(9) ECPC solenoid
(10) Modulating valve
(11) Disengaged clutch
(12) Engaged clutch Oil is supplied by the transmission pump through a filter. The oil is available to each modulating valve (10).Control of the transmission planetary is achieved by hydraulically actuated clutches that hold selected components of the planetary group stationary. Holding selected components allows the transition of power in the selected gear (speed ratio) through the transmission.Shifting of the transmission is controlled by the electronic control module (ECM). The ECM acts in response to various inputs.Inputs to the ECM module include the following information:
Selected gear
Engine speed
Ground speed
Gear limitsThe 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 clutch and the subsequent engagement of the next clutch.Each clutch is engaged by hydraulic oil pressure that is supplied by the modulating valves. The modulating valves are controlled by pulse width modulated (PWM) signals. The signals are sent by the ECM to the individual solenoids (9) on each modulating valve (10).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 proportional to the electrical current that is supplied to the solenoid (9) that controls the clutch.
Illustration 3 g00766511A high current input is made initially. The high current overcomes the inertia of the valve and the clutch components and then initiates filling of the oil passage leading to the clutch piston. The current is reduced as the clutch piston 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 disks are in contact, current is increased gradually to ensure that maximum pressure is applied to the clutch piston in a smooth manner.Electronic control of this process provides improved quality of transmission shifts.The seven forward gears are engaged by a combination of clutches.
Illustration 4 g02624777
(4) Transmission hydraulic control relief valve
(13) Oil filter
(14) Modulating valve (Torque converter lockup clutch)
(15) Torque converter input relief valve
(16) Torque converter
(17) Transmission Power is supplied from the engine, through torque converter (16), and then to the planetary transmission.The torque converter (16) allows the speeds of the engine and the transmission to be matched smoothly. Once the speed of the engine and transmission match, torque converter (16) engages in order