Fleet Angle Compensator
The fleet angle compensator is a floating sheave arrangement on an eccentric oscillating shaft. It is supported by two pillow blocks and has no direct contact to the drum except for the cable itself. This device does not spool the cable - it only compensates for a bad fleet angle (hence the name). The actual spooling is done by the special LeBus groove pattern that is on the drum core.
In order for this spooling system to function properly, certain conditions must be met. First, tension must be present at all times. The sleeve requires enough tension to hold the cable in its groove and the F.A.C. requires enough tension to maintain the sheave location and keep the shaft in the proper alignment. The tension to do this is usually significantly less than the actual load. The F.A.C. is usually designed to the breaking strength of the wire unless it is a special design. If tension is lost, then simply raising and lowering the load beyond the point of question should clear up this problem. Loose cable tends to work its way back to the cable clamp. Therefore, the cable should be un-spooled to the clamp and re-spooled on occasion.