When either directional clutch is selected the opposite clutch is relieved of pressure and vents back through the direction
selector spool. The same procedure is used in the speed selector.
The direction or speed clutch assembly consists of a drum with internal splines and a bore to receive a hydraulically
actuated piston. The piston is "oil tight" by the use of sealing rings. A steel disc with external splines is inserted into the
drum and rests against the piston. Next, a friction disc with splines at the inner diameter is inserted. Discs are alternated
until the required total is achieved. A heavy back-up plate is then inserted and secured with a snap ring. A Hub with
O.D. splines is inserted into the splines of discs with teeth on the inner diameter The discs and hub are free to increase
in speed or rotate in the opposite direction as long as no pressure is present in that specific clutch.
To engage the clutch, as previously stated, the control valve is placed in the desired position. This allows oil under
pressure to flow from the control valve, through a tube, to a chosen clutch shaft. This shaft has a drilled passageway for
oil under pressure to enter the shaft. Oil pressure sealing rings are located on the clutch shaft. These rings direct oil
under pressure to a desired clutch. Pressure of the oil forces the piston and discs against the heavy back-up plate. The
discs, with teeth on the outer diameter, clamping against discs with teeth on the inner diameter, enables the hub and
clutch shaft to be locked together and allows them to drive as a unit.
There are bleed balls in the clutch piston which allow quick escape for oil when the pressure to the piston is released.