CM-ET Lodestar - Manual (Page 20)

16
TROUBLE PROBABLE CAUSE CHECK AND REMEDY
4.) Hook raises but will not
lower.
A.) Open lowering circuit-open or shorted
winding in reversing contactor coil, loose
connection or broken wire in circuit; control
station contacts not making; lower limit
switch contacts open.
A.) Check electrical continuity and repair or
replace defective part. Check operation of
limit switch as described on page 12.
5.) Hook lowers when
hoisting control is
operated.
A.) Phase failure (three phase unit only). A.) See item 1B.
B.) Phase reversal (three phase unit only). B.) Refer to installation instruction on page 5.
6.) Hook does not stop
promptly.
A.) Brake slipping. A.) Check brake adjustment as described on
page 11.
B.) Excessive load. B.) See item 1H.
7.) Hoist operates sluggishly. A.) Excessive load. A.) See item 1H.
B.) Low voltage. B.) Correct low voltage condition as described
on page 6.
C.) Phase failure or unbalanced current in the
phases (three phase unit only).
C.) See item 1B.
D.) Brake dragging. D.) Check brake adjustment as described on
page 11.
8.) Motor overheats. A.) Low voltage. A.) Correct low voltage condition as described
on page 6.
B.) Excessive load. B.) See item 1H.
C.) Extreme external heating. C.) Above an ambient temperature of 40°C.
(104°F.), the frequency of hoist operation
must be limited to avoid overheating of
motor. Special provisions should be made
to ventilate the space or shield the hoist
from radiation.
D.) Frequent starting or reversing. D.) Avoid excessive inching, jogging or
plugging. This type of operation drastically
shortens the motor and contactor life and
causes excessive brake wear.
E.) Phase failure or unbalanced current in the
phase (three phase unit only).
E.) See item 1B.
F.) Brake dragging. F.) Check brake adjustment as described on
page 11.
9.) Hook fails to stop at
either or both ends of
travel.
A.) Limit switches not opening circuits. A.) Check switch connections, electrical
continuity and mechanical operation. Check
the switch adjustment as described on
page 12. Check for a pinched wire.
B.) Limit Switch Shaft not rotating. B.) Check for damaged Limit Switch gears.
C.) Traveling nuts not moving along shaft-
guide plate loose; shaft or nut threads
damaged.
C.) Tighten guide plate screws. Replace
damaged part.
10.) Hook stopping point
varies.
A.) Limit switch not holding adjustment. A.) See item 9.
B.) Brake not holding. B.) Check the brake adjustment as described
on page 11.
C.) Binding of Limit Switch Shaft. C.) Check Limit Switch Bearing for proper
seating.