H-20/35 VR Series Proportioning Unit
40
42942-VR-1, Issue 1
S
OLUTIONS
1. MOTOR
CIRCUIT
PROTECTOR- The
Motor Circuit Protector is
set to trip when the
electric motor draws too
much current. To restore
the motor to operation,
allow it to cool and, with
power OFF, reset the
ON/OFF Switch to ON.
Figure 21. Motor Circuit Protector
IMPORTANT: Always determine the cause of the circuit protector trip. Improper
low line voltage can also cause harm to the motor due to overheating, which will
cause the Motor Circuit Protector to trip.
2. ZERO OR LOW PRESSURE- Check position of Hydraulic Motor Switch or Pump
Switch; if either is in the OFF position, hydraulic pressure cannot be generated.
Assuming the pump is in proper working order and the Pump Switch is set to
NORMAL, the major cause of zero or low pressure is a pump that is not primed or
loses its prime. To ensure a positive prime, proceed as follows:
a) Check for correct Electric Motor Rotation. (See step 13 in the Initial Machine
Setup section of this manual.)
b) Make sure hydraulic reservoir is filled to the proper level.
c) Make sure pump case is full with hydraulic fluid.
d) Make sure inlet fitting is properly tightened; no air should be leaking into the
pump case.
3. SCREECHING-.a screeching noise is characteristic of Cavitation and is normal at
initial start-up for a maximum of 30 seconds. If the screeching continues for more
than 30 seconds, check that the inlet fittings are tight and that the pump has not lost
its prime.
A second cause of screeching can be excessive hydraulic oil temperature. Determine
that the reservoir is properly serviced and if necessary provide better ventilation to
permit the reservoir to dissipate heat more efficiently.