Determining travel distance
- Size the drum for the actual load travel. The drum must hold a length of line equal to the distance the load will actually move.
- Measure to the first change-of-direction sheave. The load can’t travel any further than the first sheave where the line changes direction, so size the drum for that distance — not the distance from the load to the winch or hoist.
- Add line for multiple parts. When the load is rigged with multiple parts of line, drum capacity must increase to take the extra line used in the rigging.
How much rope fits on a drum: see the cable capacity formula in Wire Rope Selection. Reeving: Utilizing Multiple Parts of Line.