Hyundai R 160 LC-3, Service Manual

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Power shift control
The set horsepower valve is shifted by
varying the command current level of the
proportional pressure reducing valve
attached to the pump.
Only one proportional pressure reducing
valve is provided.
However, the secondary pressure Pf
(power shift pressure) is admitted to the
horsepower control section of each pump
regulator through the pump's internal path
to shift it to the same set horsepower level.
This function permits arbitrary setting of the pump output power, thereby providing the optimum
power level according to the operating condition.
The power shift pressure Pf controls the set horsepower of the pump to a desired level, as shown
in the figure.
As the power shift pressure Pf rises, the compensating rod(623) moves to the right via the
pin(898) and compensating piston(621).
This decreases the pump tilting angle and then the set horsepower in the same way as explained
in the overload preventive function of the horsepower control. On the contrary, the set
horsepower rises as the power shift pressure Pf falls.
(3)
Delivery pressure, (P
1
+P
2
)
Delivery flow
, Q
P
f =MAX
P
f
=MIN
621 651 652 623 612 625 626
B(E)
897
875
898
611
F
C
L
P
1
P
2
P
f
P
1
D
Small diameter
chamber
Servo piston
Large diameter
chamber