RADIATOR GP 1088598 - Caterpillar

Illustration 1 g00935854
(1) Propel pump (2) Servo piston (3) Electrical displacement control valveThe propel pump is a variable displacement piston pump. The propel pump is mounted on the left side of the engine. The pump is driven by the engine flywheel.
Illustration 2 g00939309
Propel pump (2) Servo piston (3) Electrical displacement control valve (4) Combination valve (5) Port plate (6) Shaft (7) Swashplate (8) Piston (9) Barrel assembly (AA) System pressure (AB) Charge pressure (AC) Activated components (AD) SumpWhen the engine is running, drive shaft (6) and barrel assembly (9) rotate. There are nine pistons (8) in the barrel assembly. When the barrel assembly rotates, each piston follows the angle of swashplate (7). The length of the piston stroke changes when the swashplate is angled. When the swashplate angle is at zero, the pistons do not move in and out of the barrel assembly and there is no oil flow.The position of the swashplate is controlled by hydraulic servo valve (2). The position of the swashplate determines the direction of oil flow. The direction of oil flow determines the high pressure port.Charge oil from the steering pump maintains oil pressure in the piston pump in order to keep the barrel assembly full of oil. Charge oil lubricates the components of the pump.Pressure Override Relief Valve
Illustration 3 g00939340
Pressure Override Relief Valve (1) Adjustment screw (2) Passage from electrical displacement control valve (3) Passage to hydraulic oil tank (4) Locknut (5) Spring (6) Valve (7) Piston (8) Chamber (9) Slug (10) Passage from outlet of propel pump (11) Passage from inlet of propel pump (AA) System pressure (AB) Charge pressure (AC) Activated components (AD) SumpThe pressure override relief valve (POR valve) is located on the propel pump. The POR valve limits the maximum pressure on both sides of the propel loop. This valve prevents continuous dumping of excessive flow through the main relief valves in the pump. The POR valve is set at 42500 2000 kPa (6162 290 psi). The POR valve for the split drum is set at 35000 kPa (5076 psi). When the valve opens, charge oil drains from the pressure side of the servo piston through the electrical displacement control valve in the propel pump. As this charge pressure is drained, the centering springs in the servo piston move the swashplate toward the minimum pump output at the relief pressure of the POR valve.Oil from the high pressure side of the closed loop enters the POR valve at passage (10) or passage (11). This depends on the side of the closed loop that has the higher pressure. Slug (9) moves up if the high pressure is in passage (10). The slug moves down if the high pressure is in passage (11). This sends the high pressure oil to chamber (8) .When the pressure setting of the POR valve is reached, the pressure moves piston (7) and valve (6) against spring (5). This opens passage (2), and the charge oil goes through passage (3) to the tank. When the charge