Hoists may be reeved in many ways to increase capacity at decreased speed , or to get greater speed with less capacity. With the same horsepower, it is impossible to increase speed without a corresponding decrease in capacity. The reeving may be varied almost indefinitely. The worlds “single” or “double” used with hoist reeving indicate the number of ropes coming from the drum.
If only one rope comes from the drum, we have single reeving, that is 1, 2, 3, 4, or more parts single. If two ropes come from the drum and pass aroudn sheaves side by side, we have 1, 2, 3, 4 or more parts double. Remember that “parts” represents the mechanical advantage gained by reeving. “Single” or “double” means the number of ropes coming from the drum.
When buying an overhead crane, it is best to solicit proposals where the manufacturer suggests the reeving configuration, but ensure the wire rope construction and diameter are commonly available for replacement purposes. Request details on the diameter and construction and then do some research with local rigging shops to verify availability.