Service Manual

Building A Drive System
Let’s replace the cylinder with another type of
actuator a fixed displacement hydraulic motor.
With the motor in place, this system will provide
the continuous mechanical energy output
needed to propel lawn and garden equipment.
This system can reverse the direction
of travel
by changing the spool offset and reversing the
oil flow through the motor. Notice that there is
nothing in this system that will allow the output
speed to be changed.
Our hydrostatic drive systems use a variable
displacement pump and a fixed displacement
motor.
With variable output from the pump, the spool
valve
is no longer needed to control the
direction of oil flow. The speed can also be
changed with this variable output pump.
The Real Thing
If we combine the drive system with the lift
system we had previously, the result is a
hydraulic system similar to systems on many of
the larger tractors in use today.
3.4297.433
I
Productivity Series