GROVE Published 10-21-2010, Control# 198-04 7-13
5540F/YB5515 SERVICE MANUAL TRANSMISSION AND TORQUE CONVERTER
Hydraulic 2/4-Wheel Drive Unit
- Pressure ON/Spring OFF (cont'd)
2-Wheel Drive Operation (See Figure 7-13)
When the switch is in the 2-wheel drive position, solenoid
valve A is de-energized. With the solenoid A1 de-energized,
the valve spool moves under the force of the spring A2. The
oil supply to the piston C is blocked (shown at port 3). At the
same time oil vents from the back of piston C to the sump via
ports 1 and 2.
Because there is no pressure behind piston C, the friction/
counter plates of clutch pack B now freely rotate on the
output shaft, thus disengaging drive to the front axle.
Reference Only