LINES GP-HEATER 3844182 - Caterpillar

Piston Pump
Illustration 1 g01087890
(1) Actuator piston (2) Barrel (3) Pressure override valve (POR valve) (4) Port for the drive loop (5) Charge pump (6) Input shaft (7) Swashplate (8) Piston (9) Spring (10) Port plate (11) Port for the drive loopThe tandem pumps for the hydrostatic drive system are variable displacement piston pumps. The tandem pumps are mounted to the rear of the engine. The input shaft of the front pump engages a coupling that is mounted to the flywheel of the engine in order to drive the tandem pumps. When the engine is running, shaft (6) and barrel (2) are rotating. There are nine pistons (8) in barrel (2). Port plate (10) and swashplate (7) are stationary within the pump housing. Port plate (10) and swashplate (7) do not rotate. Spring (9) maintains a force against barrel (2) and port plate (10). When barrel (2) is rotating, each piston (8) follows the angle of swashplate (7) .If the angle of swashplate (7) is zero, pistons (8) do not move in and out of barrel (2) and there is no oil flow. Charge oil from charge pump (5) maintains oil pressure in the pump in order to perform the following tasks:
Keep barrel (2) full of oil.
Lubricate the pump components.
Provide makeup oil for internal loss of oil that is due to leakage.
The charge pump of the rear piston pump provides pilot oil in order to release the parking brakes.
The charge pump of the front piston pump provides signal oil in order to stroke the front piston pump and the rear piston pump.For additional information, refer to "Charge Pump".The position of swashplate (7) is determined by actuator piston (1). The speed and direction control that is located on the left console sends signal oil to the corresponding end of actuator piston (1) .As actuator piston (1) begins to move, the angle of swashplate (7) begins to increase. As pistons (8) follow swashplate (7), pistons (8) begin to move in and out of barrel (2). As pistons (8) move out of barrel (2), oil is drawn from the passage of port (4) of the drive loop through port plate (10). As pistons (8) follow swashplate (7) and the pistons move into barrel (2), the oil is pushed through port plate (10) into the passage to port (11) of the drive loop.As the angle of swashplate (7) increases, the output flow of the pump also increases.Charge Pump
Illustration 2 g01013499
Charge pump (1) Pressure override valve (POR Valve) (2) Passage (3) Crossover relief valve (4) Passage (5) Orifice (6) Passage (7) Supply passage for the charge pump (8) Passage (9) Resolver (10) Charge relief valve (11) Crossover relief valve (12) Oil filter (13) Passage (14) Passage (15) Ring gear (16) Filter bypass passage (17) Passage (18) Supply passage for charge oil from the hydraulic tank (19) Pinion gear (A) Drive loop circuit to the piston motor (B) Drive loop circuit from the piston motorThe charge pumps are gerotor pumps that are located on the rear of