HOUSING GP-REAR AXLE 1892561 - Caterpillar

Illustration 1 g03384411
Transmission Hydraulic Control
(1) Modulating Valve for No. 3 Clutch
(2) Modulating Valve for No. 5 Clutch
(3) Modulating Valve for No. 4 Clutch
(4) Modulating Valve for No. 2 Clutch
(5) Modulating Valve for No. 1 Clutch
(6) Main Relief Valve The transmission hydraulic control contains the main relief valve and the five modulating valves for the transmission clutches. The transmission hydraulic control is mounted on the top of the transmission.Oil from the transmission charging section of the power train oil pump passes through the transmission charge filter to the transmission hydraulic control.The five modulating valves control the flow of this oil to the transmission clutches. Main relief valve (6) controls the supply pressure to the modulating valves.Transmission Modulating Valves
Illustration 2 g03382791
Transmission Modulating Valve
(1) Pump Supply Oil
(2) Drain
(3) Passage To Clutch Each clutch is controlled by a transmission modulating valve. Solenoid (4) is energized in order to engage the corresponding clutch.The modulating valve allows the respective clutch to fill with oil to a pressure that is determined by the amount of current going to the solenoid. The power train ECM determines the amount of current that is supplied to the solenoid.All of the clutches except for the No. 5 clutch are energized by the same current and the same pressure. The No. 5 clutch solenoid receives less current and the No. 5 clutch receives less pressure. This strategy for the transmission modulating valves is different from previous strategies. The amount of current that is supplied to the solenoid is determined by the response of the machine, which includes the following indicators:
Speed sensors
Gear selection
Oil temperatureAs, a current is applied to solenoid (4) the modulating valve becomes engaged. As the pressure at the left end of the spool increases, the spool shifts to the right. Pump oil is now directed to the clutch through passage (3). When the clutch fills, pressure begins to increase and the clutch engages.As clutch pressure increases, the pressure plus the force of the spring moves the spool back to the left. When maximum clutch pressure is reached, a balance is maintained between clutch pressure and solenoid (4). The spool is in a metering position.De-energizing solenoid (4) returns the modulating valve to the left. Pressure on the left end of the spool drains through passage (2). This allows the spool to shift to the left. Clutch pressure is now directed to the drain and the clutch is disengaged.Electronic Main Relief Valve
Illustration 3 g03382849
Main Relief Valve
(1) Pump Supply Oil
(2) To Transmission Hydraulic Control
(3) To Torque Converter Inlet
(4) To Tank The electronic main relief valve controls system oil pressure by bleeding off pump supply oil (1) to torque converter inlet (3). The current signal from power train ECM (5) will control what the system pressure will be.