Trolleys support a hoist and position the hoist over the designated loading area, moving cargo horizontally across the beams by use of a tapered and a flat wheel.
The type of trolley that is installed depends largely on the intended use, as well as the needs of the customer. Under-running (underhung) trolleys are attached to the bottom of the crane, whereas a top running trolley is attached on top of the crane beams. Whether a trolley is under-running or top-running depends on the intended load capacity of the crane, with top-running trolleys used for heavier loads.
Hook mounted hoists are manufactured with a clevis for top hook hoist hookup. Hoist suspension permits portability of the hoist while lug suspension reduces headroom.
Lug Mounted/Crab Mounted
To form an integrated material handling unit, a trolley is attached directly to a lug suspending hoist.