General Information; Operation - New Holland LS140 Workshop Manual

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SECTION 29 - HYDROSTATIC TRANSMISSION
Op. 29 100

GENERAL INFORMATION

The hydrostatic system provides a means to transfer
power from the engine to the final drives and wheels.
It provides for an infinite number of operator speed
selections for both the forward and reverse directions
and also furnishes a means to steer the loader.
The hydrostatic pumps receive power from the
engine through a flex drive plate at the engine
flywheel. The pumps convert rotary power, devel-
oped by the engine, into a variable pressure/flow,
fluid power. This fluid power is then transferred to the
hydrostatic motors where it is converted back to
rotary motion. The rotary motion from the hydrostatic
motors is transferred to the final drive chain cases, to
the drive axles, and finally to the wheels.
Hydrostatic pump flow and fluid direction is operator
controlled by levers in the cab. Both the left and right
side pump and motor configurations are operated
independently of each other and power each side
separately.

OPERATION

The hydrostatic system is a closed loop, fluid power
3
system, that provides a smooth transition of power
3
from the engine to the wheels. The hydrostatic
1
system is made up of two piston pumps, 1, and two
piston motors, 2. Hydrostatic charge pressure is
supplied to the pumps from a back pressure valve in
the hydraulic system return line located in the engine
compartment. This provides replenishing oil for the
oil that is lost due to leakage for lubrication and
cooling purposes.
2
2
Steering is controlled by two hand levers, 3, located
in the operators cab. These hand levers control the
19992562
forward and reverse direction and the amount of oil
1
flow for the speed of the skid-steer loader. The
variable oil flow from the pumps is a result of the
rotation of the camplates within the individual pumps.
The further the control levers are pushed from
neutral, the greater the camplate angle. More oil is
then pumped to the motors resulting in an increase
in ground speed. The greatest wheel torque is when
the control levers are closest to neutral. When
operating the skid-steer loader, more power (torque),
is available by destroking the control levers, thus
increasing the loader efficiency.
29-3