Autoquip FREIGHTLIFT FLT - Manual (Page 71)

71
PROBLEM POSSIBLE CAUSE AND SOLUTION
Unit does not raise (motor is
running or humming)
• The load may exceed the rating. Remove the
excess load.
• Check for hydraulic oil leak. Correct if needed.
• Check for oil shortage in the reservoir and add
oil, if necessary.
• Rotation on the 3-hase motor may be reversed.
Reverse any two motor electrical leads.
• 3-Phase motor may be single-phasing
(humming). Check wiring, fuses, etc.
• Breather cap on the reservoir may be clogged.
Remove and clean.
• Suction screen may be clogged. The screen is
attached to the suction line in the tank. Remove
and clean. Drain and replace oil.
• Suction line may be leading air due to loose
fitting, causing cavitation. Check fittings. Bleed
air from the system (see Air Bleeding
Procedures in the Routine Maintenance
Section).
• The “DOWN” valve may be energized by faulty
wiring or it may be stuck in the open position.
Remove the solenoid and check.
• The voltage at the motor terminals may be too
low to run the pump with the existing load.
Check before measuring the voltage at the
motor terminals (or as near as possible) while
the pump is running under load. Reading the
source voltage or pump idling voltage is
meaningless. Inadequate or incorrect wiring can
starve the motor when the source voltage is
ample. Correct as necessary.
• The pump may be seized if the motor is
humming or blowing fuses or overloads.
Remove the pump with the platform in the
lowered position. The shaft should be able to be
turned by hand. Check for cracks in the
housing.
TROUBLESHOOTING ANALYSIS