FRAME AS 4Z9090 - Caterpillar

Illustration 1 g00908031
Schematic for the Transmission Hydraulic System (1) Transmission hydraulic control relief valve (2) Torque converter (3) Flow control orifice (4) Transmission oil filter (5) Modulating valve (transmission clutch) for the Number 1 clutch (6) Modulating valve (transmission clutch) for the Number 4 clutch (7) Modulating valve (transmission clutch) for the Number 2 clutch (8) Modulating valve (transmission clutch) for the Number 5 clutch (9) Modulating valve (transmission clutch) for the Number 3 clutch (10) Modulating valve (transmission clutch) for the Number 6 clutch (11) Transmission oil pump (12) Torque converter inlet relief valve (13) Suction screen and magnet (14) Oil sump (15) Transmission lubrication (16) Oil cooler (A) Pump pressure tap at the transmission hydraulic control relief valve (B) P3 Torque converter inlet pressure tap (C) Torque converter outlet pressure tap (D) Pump pressure tap at the oil filter (F) Sampling valve for the transmission oil (G) Pressure tap for the Number 1 clutch (H) Pressure tap for the Number 4 clutch (J) Pressure tap for the Number 2 clutch (K) Pressure tap for the Number 5 clutch (L) Pressure tap for the Number 3 clutch (M) Pressure tap for the Number 6 clutch (N) Transmission lubrication pressure tapThe transmission hydraulic system consists of the following components: suction screen and magnet (13), transmission oil pump (11), transmission oil filter (4), transmission hydraulic control relief valve (1), modulating valves (transmission clutch) (5-10), torque converter (2), torque converter inlet relief valve (12) and oil cooler (16) .The bottom of the output transfer gear case contains oil sump (14). Transmission oil pump (11) is a one-section gear type pump. Transmission oil pump (11) is a positive displacement pump. Transmission oil pump (11) 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 (4). Pressurized oil flows from transmission oil filter (4) through an external hose to the torque converter housing. Pressurized oil then flows through internal passages in the torque converter housing to transmission hydraulic control relief valve (1). Pressurized oil also flows from the torque converter housing to modulating valves (5-10) through the internal passages in the transmission housing.Modulating valves (5-10) are mounted on the top of the transmission under the cab. There is one modulating valve (5-10) 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. Modulating valves (5-10) are used to directly modulate the oil pressure that is sent to each individual clutch. The leakage oil from the clutches and the return oil flows to the bottom of the transmission. All oil from nonenergized clutch solenoid modulating valves (5-10) flows to the bottom of the transmission. The oil then flows