APPI said the limit switches prevent the hook from travelling up into the drum of the hoist, even if the operator does not release the in command. When the actuator plate activates the limit switch assembly, power to the hoist is cut off and only an out command is accepted.

The trolleys are offered with a variety of wheel configurations, and are suitable for both straight and curved I-beams with bend radii as small as 4ft. They can be provided with manual, chain and powered positioning systems. Other trolley options include stainless steel and spark resistant components, as well as an ultra-low profile arrangement for dual I-beam applications.