Section E - Hydraulics
Operation Description
Transmission Motor Operation 2WD
E-23 E-23
9803-9340-8
Transmission Motor Operation 2WD
K Fig 18. ( T E-23) and K Fig 19. ( T E-24)
The basic components of the transmission motor are the
rotor and rollers which are located within a machined
housing, this being called the Geroler assembly, the valve
plate, shuttle valve and back pressure relief valve. The
rollers are located in grooves in the housing so that when
the rotor is in position, cavities are formed between the
rollers, the rotor and the housing. The shape of the rotor
causes it to gyrate as it turns on the rollers so that the size
of the cavities vary as each lobe of the rotor passes.
Oil from the pump is fed into the appropriate enlarged
cavity by means of the valve plate, causing the rotor to
rotate. As it rotates the valve plate delivers oil to the next
cavity and so on to continue the rotating force on the rotor.
As each cavity reduces in size the oil is pushed out through
the valve plate and returned to the pump.
The drive from the rotor is transferred to the rear axle by
means of a splined drive shaft.
Loop Flushing System
The loop flushing system allows oil from the closed loop to
be fed into the motor casing during operation for cooling of
the motor components and to flush out any contaminants.
When there is no pressure in the loop the shuttle spool is
held in the central position by its springs. The illustration
opposite shows the high pressure in one side of the loop
causing the shuttle spool to move to the left. Oil from the
return port is fed from the opposite end of the shuttle to the
back pressure relief valve. When the return pressure
exceeds the pressure within the motor casing the relief
valve opens allowing the oil to flow into the casing to cool
and flush the motor before returning to tank. When the oil
flow is reversed in the motor the shuttle spool moves in the
opposite direction.
Note: The Back Pressure Relief Valve is not fitted on
series 2 machines.
707410-1
Fig 18.
Key
A Pump high pressure
B Pump low pressure
C Rollers
D Rotor Housing
E Rotor
F Valve Plate
Ma Shuttle Spool
Mb Back Prssure relief Valve (series 1 machines)
T Return to tank
Key
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