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The 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 the 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. |
