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| Illustration 1 | g01098044 |
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(1) Lever
(2) Shaft (3) Cam (4) Spring (5) Port (6) Port (7) Port (8) Port (9) Port (10) Orifice (11) Port (12) Valley (13) Spacer (14) Retainer (15) Spring (16) Retainer (17) Spool (18) Land | |
When the engine is at LOW IDLE, a shaft from the governor rotates lever (1). As lever (1) rotates, shaft (2) and cam (3) rotate. As cam (3) rotates within valley (12) of spacer (13), the preload on spring (4) is relieved.
Charge oil from the charge pump flows into port (11) to orifice (10). Oil flows from orifice (10) to port (5) and to port (9). The oil flows from port (5) through port (6) to the charge relief valve and to the two crossover relief valves. Also, the oil flows from port (9) through port (8) to the following components:
- Overspeed control valve
- Pressure override valve for the front pump
- Pressure override valve for the rear pump
- Brake valve
- Pilot control valve
Since the preload on spring (4) is relieved, the pressure differential across orifice (10) is greater than the combined force of spring (4) and spring (15) and spool (17) shifts to the left. As the spool shifts to the left, port (9) is opened more and port (9) allows more oil to flow through port (8). As the oil pressure in port (8) approaches the oil pressure that is regulated by the charge relief valve, the oil in port (8) acts on land (18) of spool (17). The force of the pressure on land (18) with the combined force of spring (4) and spring (15) overcome the force of the pressure in port (11) and spool (17) shifts to the right.
As the engine speed is increased, the cable from the governor rotates lever (1). As lever (1) rotates shaft (2) and cam (3), cam (3) pushes on valley (12) of spacer (13). This movement increases the force of spring (4).
With the increase of engine speed, the flow of oil from the charge pump increases to port (11). The increased flow across orifice (10) creates a greater pressure differential across orifice (10). The increased pressure differential is sufficient to shift spool (17) to the left and flow through port (9) is maintained.