Construction
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| Illustration 1 | g00537895 |
Main pump (1) Port (negative flow control pressure for front pump) (2) Outlet port (rear pump) (3) Port (negative flow control pressure for rear pump) (4) Outlet port (pilot pump) (5) Outlet port (front pump) (6) Drain port (7) Front pump (8) Port (power shift pressure) (9) Port block (10) Rear pump (11) Pilot pump (12) Inlet port (13) Inlet port (pilot pump) | |
The main pump consists of front pump (7), rear pump (10) and port block (9). The main pump and the port block are bolted together in order to form one assembly. The front pump and the rear pump are identical.
Oil from the hydraulic tank flows into inlet port (12) of port block (9). Port block (9) divides the oil between front pump (7) and rear pump (10). Front pump (7) delivers oil to the hydraulic system through outlet port (5). Rear pump (10) delivers oil to the hydraulic system through outlet port (2). Pilot pump (11) draws oil through inlet port (13). Pilot pump (11) delivers oil to the pilot system through outlet port (4) .
The power shift pressure is determined by the electronic controller. The power shift pressure flows into the main pump through port (8). The negative flow control pressure from the main control valve flows into front pump (7) through port (1). The negative flow control pressure from the main control valve flows into rear pump (10) through port (3) .
Front shaft (14) of front pump (7) is coupled with the engine flywheel. Front shaft (14) is connected in series to the shaft of rear pump (10). When the engine flywheel rotates front pump (7) and rear pump (10) rotate.
Main Pump Operation
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| Illustration 2 | g00538070 |
Main pump (14) Front shaft (15) Swashplate (16) Plate (17) Retainer (18) Slipper (19) Piston (20) Barrel (21) Port plate (22) Passage | |
Front pump (7) and rear pump (10) are identical in operation. The front pump will be used in order to describe the operation of the front pump and the rear pump.
Oil from the hydraulic tank flows through inlet port (12) and into port block (9). The oil in port block (9) flows through passage (22) of port plate (21). The oil then flows into the bores of barrel (20) .
When front shaft (14) is driven by the engine flywheel, barrel (20) rotates. As barrel (20) rotates pistons (19) and slippers (18) rotate on plate (16). Slippers (18) are retained to plate (16) by retainers (17). The angle of plate (16) determines the displacement of pistons (19). The angle of plate (16) is controlled by the angle of swashplate (15) .
As barrel (20) rotates pistons (19) move in and out of the bores. As pistons (19) move out of the bores of barrel (20), pistons (19) draw oil into the bores. As pistons (19) move into the bores of barrel (20), pistons (19) force the oil out of the bores.
The oil that is forced out of the bores flows into the main control valve. The oil from front pump (7) exits the main pump through outlet port (5). The oil from rear pump (10) exits the main pump through outlet port (2). Outlet port (5) and outlet port (2) are part of port block (9) .