HOSE AS 1408787 - Caterpillar

Illustration 1 g06039570
Transmission Hydraulic Control
(1) Torque converter relief valve
(2) Transmission hydraulic control relief valve
(3) Transmission clutch solenoid modulating valvesThe transmission hydraulic control controls the oil pressure to the torque converter, to the transmission clutches, and to the lubrication circuits. The transmission hydraulic control also controls the flow of oil to the clutches. The transmission hydraulic control is installed on the top of the planetary transmission and on the side of the torque converter housing. The transmission hydraulic control consists of the following components: transmission hydraulic control relief valve (2), six clutch solenoid modulating valves (3) and torque converter relief valve (1).Pressurized oil for the operation of the transmission hydraulic control flows from the transmission oil pump to the transmission oil filter. The oil flows through a hose to the oil inlet in the torque converter housing. The oil flows through internal passages in the torque converter housing to supply transmission hydraulic control relief valve (2) with oil. The oil also flows through internal passages in the transmission housing to supply the six clutch solenoid modulating valves (3) with oil.The six clutch solenoid modulating valves (3) are mounted on the top of the transmission under the cab. The six transmission clutches have an individual clutch solenoid modulating valve (3). To move the machine, a direction clutch solenoid and a speed clutch solenoid must be energized. The clutch solenoid modulating valves (3) are used to directly modulate the oil pressure that is sent to each individual clutch.Table 1 that follows provides the combination of the energized solenoids and engaged clutches for each forward speed and for each reverse speed.
Table 1
Speed Range and Direction Clutches and Solenoids that are Engaged
Fourth Speed Forward 3 and 2
Third Speed Forward 4 and 2
Second Speed Forward 5 and 2
First Speed Forward 6 and 2
Neutral 3
First Speed Reverse 6 and 1
Second Speed Reverse 5 and 1
Third Speed Reverse 4 and 1
Fourth Speed Reverse 3 and 1 Note: The 815/816 have four forward speeds and four reverse speeds.Transmission hydraulic control relief valve (2) controls the pressure of the oil that is supplied to clutch solenoid modulating valves (3). The oil pressure overcomes the spring force of the transmission hydraulic control relief valve. Torque converter inlet P3 oil then flows to the torque converter.Torque converter relief valve (1) limits P3 torque converter oil pressure to a maximum of 900 70 kPa (130 10 psi). Torque converter relief valve (1) is located in the torque converter housing. Transmission hydraulic control relief valve (2) is on the opposite side of the torque converter housing as the torque converter relief valve (1).Reference: For additional information on the operation of the clutch solenoid modulating valves, refer to the Service Manual module for Systems Operation, "Modulating Valves (Transmission Clutch)" for the machine that is being serviced.