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A Horizontal Load Reversing (HLR) drum allows (2) individual wire ropes to be spooled onto the first layer of a mutual, grooved, drum. These cables are usually rigged through a series of blocks/sheaves and attached to either end of a common load. As one wire rope winds onto the drum, the other rope winds off an equal amount. This allows precise positioning of the load anywhere along its length of travel. Since line speeds increase as additional layers (of wire rope) are spooled onto a drum, it is critical with HLR applications to keep both wire ropes on the first layer. Having the wire ropes on different layers would cause each rope to travel at different speeds. This could result in one rope spooling onto the drum faster than the other, possibly over tightening and stressing the rigging components.
Many factors such as drum length, barrel diameter, and wire rope size, affect the amount of travel a winch drum can provide on the first layer. Once the travel distance (“A”), line pull, and wire rope size are known then a suitable drum can be engineered. Please be aware that (practical) drum lengths are finite and there may be applications where the use of an HLR system would not be feasible. In those cases other alternatives such as using (2) winches working in tandem can be investigated.
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It is important for the factory to know how each of the cables will be coming off of the drum. This allows the correct grooving to be provided and to insure that no winch components would physically interfere with either of the cables. Generally, a drawing (“B”) or sketch supplied with the inquiry is all that is required.