Hyundai HX145LCR Manual page 65

(2) Total horsepower control
The regulator decreases the pump tilting
angle (delivery flow) automatically to limit
the input torque within a certain value with
a rise in the delivery pressure P1 of the
self pump and the delivery pressure P2 of
the companion pump.
(The input horsepower is constant when
the speed is constant.)
Since the regulator is of the simultaneous
Delivery pressure, (P +P )
1 2
total horsepower type that operates by the
sum of load pressures of the two pumps
in the tandem double-pump system, the
prime mover is automatically prevented
from being overloaded, irrespective of the
load condition of the two pumps, when
horsepower control is under way.
Since this regulator is of the simultaneous
total horsepower type, it controls the tilting
angles (displacement volumes) of the two
pumps to the same value as represented
by the following equation :
Tin = P1 q/2 + P2 q/2
= (P1+P2) q/2
The horsepower control function is the
same as the flow control function and is
summarized in the following. (For detailed
behaviors of respective parts, refer to the
section of flow control).
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