 | |
| Illustration 1 | g00661153 |
(1) Cold oil bypass relief valve. (2) Shaft. (3) Power train pump. (4) Charge pump. (5) Charge pressure relief valve. (6) Filter. | |
The charging system provides low oil pressure to the hydrostatic drive system, the brake system, the speed control system, and the all wheel drive system ( 580 Wheel Harvester only).
The hydrostatic drive system utilizes the charge system to replenish the oil that is lost due to normal leakage.
The all wheel drive system and the differential control system utilize charge pump oil in order to shift valve spools. These valve spools then direct the high pressure oil from power train pump (3) .
The speed control system utilizes charge pump oil to control the speed of the travel motors and the displacement of the travel motors.
The brake system utilizes charge pump oil to overcome the spring pressure of the travel motor brake. When the spring pressure is overcome, the brake is released.
Charge pump (4) is mounted on power train pump (3) and driven by a shaft (2). Charge pump (3) is an internal gear pump that provides pressure in the charge circuit. The oil pressure in the charge circuit is controlled by charge pressure relief valve (5) and cold oil bypass relief valve (1) .
Charge pump oil flows through cold oil bypass relief valve (1). Cold oil bypass relief valve (1) limits the pressure in the charge system to a maximum pressure of 2400 kPa (350 psi).
Filter (6) is located on power train pump (3). Filter (6) provides filtration in the charge circuit. Filter (6) is protected by a bypass valve.
If the filter element in filter (6) fills with debris, a restriction to the hydraulic oil flow results. This causes a hydraulic oil pressure to increase. If the hydraulic oil pressure increases to 172 ± 2 kPa (25 ± .3 psi), the bypass valve will open. This allows oil to bypass the filter element.
When the hydraulic oil bypasses the filter element, the debris in the hydraulic oil will cause damage to other system components. Make sure that correct maintenance is performed so that the filter element does not block the flow of clean hydraulic oil to the charge system.
Charge pressure relief valve (5) limits the pressure to the proportional solenoids on the power train pump to a maximum pressure of 1800 kPa (260 psi).