824G Series II Wheel Tractor, 825G Series II Soil Compactor and 826G Series II Landfill Compactor Power Train Caterpillar


Transmission Hydraulic System

Usage:

824G II AWW



Illustration 1g00873827

Schematic for the Transmission Hydraulic System

(1) Transmission hydraulic control relief valve

(2) Torque converter inlet relief valve

(3) Torque converter

(4) Torque converter outlet relief valve

(5) Transmission oil filter

(6) Clutch solenoid modulating valve for the Number 1 clutch

(7) Clutch solenoid modulating valve for the Number 4 clutch

(8) Clutch solenoid modulating valve for the Number 2 clutch

(9) Clutch solenoid modulating valve for the Number 5 clutch

(10) Clutch solenoid modulating valve for the Number 3 clutch

(11) Clutch solenoid modulating valve for the Number 6 clutch

(12) Transmission oil pump

(13) Suction screen and magnet

(14) Oil sump

(15) Transmission lubrication

(16) Oil cooler

(A) P3 Torque converter inlet pressure tap

(B) Torque converter outlet pressure tap

(C) Pump pressure tap at the oil filter

(D) Pressure tap for the Number 1 clutch

(E) Pressure tap for the Number 4 clutch

(F) Pressure tap for the Number 2 clutch

(G) Pressure tap for the Number 5 clutch

(H) Sampling valve for the transmission oil

(J) Pressure tap for the Number 3 clutch

(K) Pressure tap for the Number 6 clutch

(L) Transmission lubrication pressure tap

The transmission hydraulic system consists of the following components: suction screen and magnet (13), transmission oil pump (12), transmission oil filter (5), transmission hydraulic control relief valve (1), clutch solenoid modulating valves (6-11), torque converter (3), torque converter inlet relief valve (2) and oil cooler (16) .

The bottom of the output transfer gear case contains oil sump (14). Transmission oil pump (12) is a one-section gear type pump. Transmission oil pump (12) is a positive displacement pump. Transmission oil pump (12) supplies oil to the transmission hydraulic system by pulling oil from oil sump (14). The oil flows through the suction screen and magnet (13). Oil is supplied to the pump inlet through a tube that is mounted to the pump inlet and to the output transfer gear case. Pressurized oil flows from the pump outlet to externally mounted transmission oil filter (5). Pressurized oil flows from transmission oil filter (5) through an external hose to the transmission case. Pressurized oil then flows through internal tubes to transmission hydraulic control relief valve (1) .

Clutch solenoid modulating valves (6-11) are mounted on the top of the transmission under the top cover. There is one clutch solenoid modulating valve (6-11) for each of the six transmission clutches. In order to move the machine, a direction clutch solenoid and a speed clutch solenoid must be energized. Clutch solenoid modulating valves (6-11) are used to directly modulate the oil pressure that is sent to each individual clutch. The clutch leakage oil and the return oil flows to the bottom of the transmission. All oil from nonenergized clutch solenoid modulating valves (6-11) flows to the bottom of the transmission. The oil then flows to oil sump (14) in the bottom of the output transfer gear case.

Transmission hydraulic control relief valve (1) controls the pressure of the oil that is supplied to clutch solenoid modulating valves (6-11). Oil flows into transmission hydraulic control relief valve (1) at a maximum pressure of 2620 ± 35 kPa (380 ± 5 psi). The oil pressure overcomes the spring force of transmission hydraulic control relief valve (1). The torque converter inlet oil flows to torque converter (3) at approximately 690 kPa (100 psi). Torque converter inlet relief valve (2) limits P3 torque converter inlet oil pressure to a maximum of 1060 ± 100 kPa (154 ± 15 psi).

The oil from torque converter (3) flows to relief valve (4). Relief valve (4) maintains the oil pressure that is inside torque converter (3) at a minimum of 414 ± 34 kPa (60 ± 5 psi). The oil flows from relief valve (4) to transmission oil cooler (16) .

Transmission oil cooler (16) is located on the left side of the machine. Transmission oil cooler (16) is attached to the side of the engine. After the oil has been cooled, the oil flows to the transmission. The oil provides lubrication to the transmission and cooling to the transmission. The oil flows through internal passages in the transmission to the bearings, the gears, and the clutches. The oil then flows to the bottom of the transmission. The oil then flows to oil sump (14) in the bottom of the output transfer gear case.

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