Daedong DSC48, Workshop Manual

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-18 Apr. 2007
DSC48
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2.2 STRUCTURE AND FUNCTION
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(1) Variable swash plate (3) Cylinder
(2) Piston (4) Fixed swash plate
2.2.1 PUMP AND MOTOR
The structures of the pump and motor are very similar.
But, the pump is a variable capacity type with the variable
swash plate, while the motor is a
fi xed capacity type with
the fi xed swash plate.
The cylinders and pumps of the pump and motor are con-
nected to the hydraulic circuits. The piston is adhered
to the swash plate surface. As the cylinder in the pump
rotates, the piston moves along to the inclined surface of
the swash plate. Then, the oil is sucked and discharged
as the piston reciprocates in the cylinder. The discharged
oil by the pump piston pushes the motor piston away from
its cylinder. Then, the motor piston pushes its swash plate
and generates force to rotate the cylinder. Also, the rotating
direction and speed of the motor depends on the direction
and amount of oil
fl ow from the pump.
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(1) Variable swash plate (5) Swash plate shaft
(2) Piston (6) Swash plate shaft cover
(3) Pump side (7) Cylinder block P
(4) Thrust plate
2.2.2 VARIABLE SWASH PLATE
When the main shift lever is moved, its movement is trans-
ferred to the swash plate through the link.
As the swash plate shaft and variable swash plate are at-
tached as a unit, the plate moves along the shaft and its
angle changes. The variable swash plate changes the ro-
tating direction and speed of the motor shaft.
The amount and direction of oil discharged from the piston
can be controlled by changing the angle of the swash plate
from the swash plate shaft.
(1) Charge pump (2) Pump cover
2.2.3 CHARGE PUMP
The pump and motor are connected through a closed cir-
cuit and most of oil circulates in this circuit.
However, some amount of oil leaks to lubricate the sliding
parts. Therefore, the HST's closed circuit should be replen-
ished with oil. This operation is done by the charge pump
which is attached to the input shaft.
The oil discharged from the charge pump comes to replen-
ish the closed circuit through the check valve in the low
pressure section, where oil returns from the motor.
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