SAFETY MECHANISM FOR HOISTING DRUMS

摘要

A safety system for applying an emergency brake (11) (224) to a hoist drum (11) (D) when abnormal loading, malfunction or excessive load handling speeds are encountered. A mechanical out-of-sync detector (20) (216) receives a first rotational input via suitable transmission components from the hoist motor (3) (M) and a second rotational signal via other transmission components from the drum (11) (D). A significant difference between these signals causes a differential action in the output means (29) (227) of the detector (20) (216) resulting in the application of the brake (11) (224). Application of the brake is enhanced by strong biasing means (74) (284) to apply the brake upon release of latch devices (76) (280) (332) associated with reset means. Centrifugal means (47) (97) prevent overspeed of the drum.