Yale Lift-Tech SHAW-BOX, Operation, Service & Parts Manual

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Page 21
SECTION Vl - TROUBLE SHOOTING (continued)
Trouble Probable Cause Possible Remedy
6-1. Hoist Will Not Operate d. Contactor assembly not d. Check contact points. Replace if
(Continued). functioning. excessively burned or pitted. Check for
burned out contactor coils. See that
necessary jumper wires are properly
installed.
e. No control voltage. e. Check transformer fuse. If blown, check for
grounding and/or shorts in the push button
station. Check the transformer coil for signs
of overheating. Replace transformer if
burned out. Verify the transformer
secondary is the same voltage as the coils
to which it is connected.
f. Motor burned out. f. Replace motor. Check input power supply.
Check hoist motor connections.
6-2. Hook Moves in Wrong a. Reverse phasing on three- a. Interchange any two power supply line
Direction. phase hoists. leads. Refer to SECTION II.
b. Hoist or push button wired b. Check wiring connections with appropriate
wrong. wiring diagram.
6-3. Hook Will Raise But Not Lower. a. Lower electrical circuit open. a. Check for loose connections. See that
necessary jumper wires are properly
installed on contactor.
b. Contactor not functioning. b. Check for burned or pitted contact points
or burned out contactor coil.
6-4. Hook Will Lower But Not Raise. a. Excessive load. a. Reduce loading to rated load of hoist, as
shown on nameplate.
b. Hoist circuit open. b. Check for loose connections. See that
necessary jumper wires are properly
installed on contactor.
c. Contactor not functioning. c. Check for burned or pitted contact points or
burned out contactor coil.
6-5. Hoist Will Not Lift Rated Load. a. Low voltage a. See that power supply current is same
voltage listed on motor data plate. Check
size of power supply lines.
b. Overload Clutch not properly b. See SECTION VII, Paragraph 7-5.
adjusted.
6-6. Load Drifts Excessively When a. Excessive load. a. Reduce loading to rated load, as shown on
Hoist Is Stopped. nameplate.
b. Motor brake not holding. b. With No Load, check hoist for drift. If
drifting is excessive, inspect motor brake
(SECTION V, paragraph 5-5) and adjust as
outlined in SECTION VII, Paragraph 7-2.
c. Load brake not holding. c. (1) After determining that the motor brake
is working properly, attach rated load to
hook and operate hoist. If the load
accelerates during lowering, the load brake
is not functioning properly. See Section V,
paragraph 5-6 for replacing worn or
damaged parts.
(2) If load brake checks O.K., magnetic
motor brake needs adjustment (see b
above).