PUMP GP-WATER 5279976 - Caterpillar

Directional Control Valve
Illustration 23 g01039636
Directional Control Valve
(91) Feedback lever
(92) Lever
(93) Spool
(94) Passage (charge oil)
(95) Control valve body The propel lever delivers a mechanical input to lever (92). The input determines the amount of rotation of spool (93). The output of the propel pump is proportional from 0 to 100 percent. This is based on the amount of control oil that is allowed to flow from passage (94) through spool (93) and into the servo piston. Control oil flows through passage (94) to spool (93). The oil is then sent to either the right end of the servo piston or left end of the servo piston. The control oil pressure shifts the servo piston, and a mechanical signal is sent to the swashplate. This upstrokes the propel pump.Drum Interlock Valve
Illustration 24 g01039637
(96) Drum interlock valve (drum propel pump) The axle interlock valve and drum interlock valve (96) prevents the pump swashplate from moving out of neutral when the parking brake is applied.The interlock valves have a solenoid on one end in order to move the valve spool. There is a spring on the other end in order to position the valve spool when the solenoid is not energized.When the parking brake switch is in the ON position, the solenoid for the interlock valve is not energized. In this position, the interlock valve is open directing control oil to the hydraulic tank. The servo piston shifts to the neutral position. This causes the swashplate to move to the neutral position.When the machine is in neutral and the parking brake switch is switched to the OFF position, the brake relays will de-energize allowing the solenoid for the axle interlock valve to energize. In this position, the interlock valve shifts and the charge oil flows to the directional control valve. When the charge oil becomes available for the directional control valve, any movement of the propel lever causes the servo piston to shift the swashplate.Oil Flow for the Drum Propel Pump
Propel Lever in NEUTRAL Position
Illustration 25 g01047180
Drum Propel Pump
(51) Servo piston
(52) Direction control valve
(53) Makeup and relief valve
(54) Port plate
(55) Barrel assembly
(56) Piston
(57) Slipper feet
(58) Swashplate
(59) Drive shaft
(91) Feedback lever
(AA) Tank pressure
(BB) Charge pressure
(CC) Activated components When the propel lever is in NEUTRAL position, charge pressure oil will be blocked by directional control valve (52). The oil that is acting against servo piston (51) will be open to the hydraulic tank. The centering springs in the piston will center the servo piston. As a result, the angle of the swashplate will be minimal. Pistons (56) will not move in and out in barrel assembly (55) as the pistons rotate. The axle propel pump will not produce oil flow. As a result, the propel motors will not turn.The steering pump supplies the propel pumps with charge pressure oil. The charge pressure oil will continue to flow to the charge circuit in the propel pumps. If the pressure in the forward circuit or the reverse circuit falls below charge oil pressure, charge pressure oil will open either