Komatsu Utility SK714-5, Shop Manual

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10-8 SK714-5 SK815-5 SK815-5 turbo
DESCRIPTION
The final drive motor consists of:
1. 2-speed hydraulic motor
2. Selector valve
3. Reduction gearing
1.
HYDRAULIC MOTOR
Function
The hydraulic motor is of the axial piston type, and converts hydraulic energy supplied by the pump into rotary motion.
Operation
The hydraulic oil arriving from the selector valve is sent on to the valve plate (1). When the oil is sent to port “A” of the
valve, it flows into the corresponding port on the cylinder block (2) and presses against the pistons (3).
This pressure is converted into rotary motion by a swash plate (4) and hence transmitted to the shaft (5). The shaft and
the cylinder block have been integrated into one piece by means of splined toothing.
The return oil is sent to the pump through port
“B” .
Rotation in the opposite direction is achieved by sending the oil to port “B” instead of to port “A” ..
Varying the displacement
The swash plate (4), which has two surfaces “A” and “B” on the side opposite the sliding side for the shoes (6), is sup-
ported by two bearings (7) attached to the body of the motor (8).
The position of the bearings is eccentric with respect to the axis of the shaft and when running at low speed the surface
“A” remains in contact with the body of the motor through the pressure exerted by the pistons (3) and by the force of a
spring (9) mounted in the cylinder block (2).
The angle of the swash plate is
α
.
When an increase in speed is demanded, the oil is sent under pressure to the command piston (10). The command pi-
ston (10) moves to the left (
) until the surface “B” makes contact with the housing and the angle of the swash plate
becomes
β
(the displacement of the motor is reduced).
RKS01050
5
4
2
1
3
B
A
STRUCTURE AND FUNCTION
FINAL DRIVE