OPERATION
3-32 / Pierce Pumper
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3-14.3 Pump Pressure Control - Without Pressure Governor
This section applies to apparatus not equipped with a pressure governor. See “Pump Pressure Control With
Pressure Governor (Pumping)” on page 3-34 for pressure governor-equipped apparatus.
Figure 3-5: Engine Speed and Pump Pressure
POM0014, 0013, 0003
1. Observe interlock lamp.
If the interlock light above the Hand Throttle Control on the pump panel is ON, it means you can change engine
RPMs.
Two sets of conditions will turn ON the light:
— Parking brake applied.
— Transmission in 4th gear lockup.
— Pump shift complete.
OR
— Parking brake applied.
— Transmission is in NEUTRAL.
If either set of conditions fails, the hand throttle will be disabled. Engine speed control is then controlled ONLY
by the foot throttle pedal in the cab. That is the manual override.
2. Increase engine speed using hand throttle.
a. Turn counterclockwise to the left to INCREASE engine speed.
b. Turn clockwise to the right to DECREASE engine speed.
c. Adjust friction collar to set resistance to main constant engine speed.
d. Press red button to return engine speed to IDLE.
For non-emergency situations, return the engine speed to idle by turning the hand throttle knob.
Continual use of the red button will wear out the threads on the screw and cause premature failure of
the hand throttle.
HAND THROTTLE DISCHARGE RELIEF
VALVE
MASTER DISCHARGE PRESSURE
GAUGE (RIGHT)
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