Pump Actuator
| ITEM | DESCRIPTION |
|---|---|
| D | Working pressure |
| E | Atmospheric pressure |
| 1 | Multiplate clutch |
| 2 | Bleed valve |
| 3 | Pressure regulating valves closed |
| 4 | Electric motor |
The twin speed transfer case is equipped with an innovative electro-hydraulic clutch for optimum AWD performance. The electro-hydraulic pump contains a centrifugal pressure control device.
In AWD mode, the pump actuator is activated and pressure from the pump actuator compresses the multiplate clutch pack enabling the transfer of torque from the transmission to the front axle.
In RWD state, the pump actuator is OFF and the multiplate clutch is in open state, there is no torque transfer to the front axle.
The pump actuator is powered by an electric motor and consists of:
- A barrel with pistons (A)
- A pump-lid with suction and discharge ports (B)
- A swash plate and pressure regulating valves (C).
Rotary motion is converted to linear motion by the angular swash plate. As the barrel rotates, the pistons start to reciprocate inside the barrel. Hence the oil from the suction port is delivered to the discharge port, creating a flow. As the flow to the coupling piston increases, the pressure on this working side also increases.
When the required pressure is building up, the centrifugal force is greater than the hydraulic force and the pressure regulating valves remain closed.
The level of pressure conveyed by the pump depends on the required torque. Under conditions of poor traction at the rear axle, a high pressure is delivered to fully engage the clutch.