DRIVE GP-FINAL 2993570 - Caterpillar

Illustration 1 g00593415
Hydraulic Cooler Shutoff Valve (1) Solenoid valve (2) Chamber (poppet spring) (3) Passage (poppet spring chamber) (4) Spring (5) Poppet (6) Chamber (return oil to the hydraulic tank) (7) Orifice (8) Line (inlet to the hydraylic cooler shutoff valve)Solenoid valve (1) is de-energized during start-up of the machine. When solenoid valve (1) is de-energized, poppet spring chamber (2) is vented through passage (3) and solenoid valve (1). The force of the combined return oil moves poppet (5) to the left and sending the combined return oil into chamber (6). The combined return oil from chamber (6) passes through the hydraulic oil cooler to the hydraulic tank. After the machine has started, the machine control module energizes solenoid valve (1). Solenoid valve (1) blocks passage (3). The combined return oil goes through orifice (7) in poppet (5) into chamber (2). The pressurized oil and spring force hold poppet (5) seated. Poppet (5) blocks the combined return oil from passing through the cooler shutoff valve and the hydraulic oil cooler. The machine control module will monitor the hydraulic oil temperature and the machine control module keeps solenoid valve (1) energized until the temperature of the hydraulic oil increases to 38 °C (100 °F).At 38 °C (100 °F), the machine control module de-energizes solenoid valve (1). De-energizing solenoid valve (1) allows poppet (5) to move left sending the combined return oil to the hydraulic oil cooler and the hydraulic oil tank. This condition remains until the temperature decreases to 27 °C (80 °F). The machine control module energizes solenoid valve (1) at 27 °C (80 °F). The combined return oil bypasses the hydraulic oil cooler and flows directly to the hydraulic tank. Proper operation of the cooler shutoff valve prevents overcooling of the hydraulic system.