Warner Electric CB Series and Super CB Series Sizes 2, 4, 5, 6 and 8 - Manual (Page 8)

8 Warner Electric • 800-825-9050 P-258 • 819-0406
Troubleshooting Checklist
4. Troubleshooting the Clutch/Brake Unit
When the brake spring is engaged, i.e., fully wrapped down, the input should be free to rotate by hand. Wrapping the
brake spring down completely can be accomplished by rotating the output shaft in the driving direction until it cannot
travel any further. Please note that units with anti-overrun springs (most units) will allow the input hub to turn only in
the direction of rotation.
Possible Problem Recommended Action
1. Continuous driving (input and output hubs locked
together - unit continues to drive even with collar
blocked)
A. The spring differential setting is too small. Reset differential
(see Section 5 “CB Spring Differential Adjustment”).
B. The endplay (axial clearance between hubs) setting is too
close. Reset the endplay by moving the output sleeve on
the shaft until a minimum of .003" to .006" clearance is
achieved.
CAUTION: Use a brass hammer to avoid shaft
damage.
C. The hubs are necked down (worn at the spring crossover
point) and the spring is caught between the two hubs and
cannot release. This could be a result of excess torque
being applied to the unit. Re-evaluate sizing. Replace unit
or rebuild with “Heavy Repair Kit” and then reset endplay.
Note: On Rebuilding Units: As a general rule, when
springs are replaced, the hubs should be as well. Given
that the springs and hubs are the majority of the cost of
the unit, it is often not economically feasible to rebuild units
when replacement of the springs and hubs is required.
D. The bearing surface between the input and output hubs
is galled and the unit should be replaced. If galling was
caused by contaminants, add a dust cover to reduce
contamination (See Section 6). If galling was caused by
excessive radial side loading or an overhung load, correct
this condition by mounting the input member properly
(See Section 2).
2. Input is free, but the clutch won’t engage when actuated. A. The spring differential setting is too loose. Reset the
differential (see Section 5 “CB Spring Differential
Adjustment”).
B. Check the clutch spring for damage. Replace as necessary
with “Light Repair Kit.”
C. The control collar cannot move because foreign matter is
blocking it. Clean the unit and add a dust cover to reduce
contamination (See Section 6).
D. The actuator/cam tip clearance is inadequate. Reset the
airgap by realigning the coil (See Section 3, Step 3A).
E. The coil has failed. Replace coil and realign to set airgap.
(See Section 3, Step 3A).
3. Clutch/Brake stalls motor when engaged. A. See solutions to Problem 1, “Continuous driving.”
4. Control collar tang slot ripped out. A. The spring differential setting was incorrect or altered.
Replace the collar and reset the spring differential (See
Section 5).
B. Unit was rotated in reverse direction. Replace broken parts
with “Light Repair Kit.” Do not reverse unit.
C. The torque or inertia of the application is too large for the
unit. Re-evaluate unit size.
Input Output
Hub Hub
Crossover point is
where the spring crosses
over from one hub to
the other.
Figure 6