Hydraulic Winch Q & A

Q: What is fleet angle?
A: From the winch, the cable generally runs over a sheave at some distance away from the winch. The winch is normally aligned so that the cable forms a 90 degree angle with the drum axis when the cable is at the midpoint of the drum. When the cable is at its most extreme position left or right of center, the cable is at a slight angle of deviation from its centerline position. This angle is termed the fleet angle.

If the fleet angle is small enough, generally in the range of 0.5 and 1.5 degrees, and there is at least a small tension on the cable (3 to 7 percent of cable breaking strength is usually sufficient), then the cable will spool onto the drum smoothly. Each wrap of cable remains tightly coiled to the adjacent wrap. The system design must provide for a sheave at a sufficient distance from the winch to maintain this fleet angle. For a drum length of 20 inches, the distance to first sheave must be at least 30 feet.

To help reduce the distance to the closest sheave, you can use a drum with LeBus® lagging. This increases the maximum fleet angle to 2 degrees. Distance to the first sheave on a 20-inch drum length is reduced to 24 feet.