How do you work out the fleet angle for a winch?

Answer 1

If you're designing a system for hoisting a load using a pulley and a motorized winding drum, you must space the drum and the pulley sheave apart far enough to maintain a safe "fleet angle." The fleet angle of a sheave-and-drum pulley system refers to the maximum angle from the front of a fixed sheave to the outermost position along the drum as it winds the fiber (e.g., rope, cable or wire). If the angle is too small, you'll won't be able to wind enough fiber for the system to be useful; if the angle is too large, the fiber will be pulled off the sheave's track, requiring you to shut down and repair the system.

. 1 Measure the direct distance from the front of the fixed sheave to the axis of the drum (in feet).

• 2 Measure the length of the smooth-faced drum from the center to the left edge (in feet).

3 Divide the result from Step 2 by the result from Step 1.

• 4 Calculate the arctangent of the result from Step 3. This is the left fleet angle of the drum.
• 5 Measure the length of the smooth-faced drum from the center to the right edge (in feet).
• 6 Divide the result from Step 5 by the result from Step 1.
• 7 Calculate the arctangent of the result from Step 6. This is the right fleet angle of the drum.