Harrington Hoists and Cranes RH Wire Rope Hoist - Manual (Page 65)

65
Table 7-1 Troubleshooting Guide
Symptom Cause Remedy
Hoist lifts but will not
lower
Down circuit open
Check circuit for loose connections. Check down limit switch for
malfunction.
Broken conductor in
pendant cord Check the continuity for each conductor in the cable. If one is
broken, replace entire cable.
Faulty magnetic
contactors Check coils for open or short circuit. Check all connections on
motor circuit. Check for burned contacts. Replace as needed.
Faulty switch in
pendant Check electrical continuity. Check electrical connections.
Replace or repair as needed.
Hoist lowers but will
not lift
Hoist overloaded Reduce load to within rated capacity of hoist.
Low voltage in hoist's
power supply
Determine cause of low voltage and bring to within plus or minus
10% of the voltage specified on the motor nameplate. The
voltage should be measured at the hoist contactor.
Up circuit open
Check circuit for loose connections. Check up limit switch for
malfunction.
Faulty magnetic
contactors Check coils for open or short circuit. Check all connections on
motor circuit. Check for burned contacts. Replace as needed.
Broken conductor in
pendant cord Check the continuity of each conductor in the cable. If one is
broken, replace entire cable.
Faulty switch in
pendant Check electrical continuity. Check electrical connections.
Replace or repair as needed.
Hoist will not lift rated
load or does not have
the proper lifting speed
Hoist overloaded Reduce load to within rated capacity.
Low voltage in hoist's
power supply
Determine cause of low voltage and bring to within plus or minus
10% of voltage specified on the motor nameplate. The voltage
should be measured at the hoist contactor.
Brake drags Check motor brake adjustment for proper clearance.
Load drifts excessively
when hoist is stopped Motor brake not
holding Clean and inspect brake lining. Check brake adjustment for
proper clearance.
Trolley drifts
excessively when
stopping
Motor brake not
holding Clean and inspect brake lining. Check brake adjustment. Replace
if necessary
Hoist and/or Trolley
Motor or brake
overheating
Excessive load Reduce load to within rated capacity of hoist.
Excessive duty cycle Reduce frequency of lifts and/or trolley movement.
Wrong voltage or
frequency Check voltage and frequency of power supply against the rating
on the nameplate on the motor.
Brake drags Check brake adjustment for proper clearance.
Extreme external
heating
Above an ambient temperature of 104°F, the frequency of hoist
operation must be reduced to avoid overheating of the motor.
Special provisions should be made to ventilate the hoist or
otherwise shield it from the heat.