Cam driven wedge braking system for multi-stage lifts

摘要

Apparatus for braking relative vertical movement between two vertical members includes linkage connected either directly or indirectly to a cable pulley-mount that is spring loaded and moves cams that wedge in between two vertically moveable members when cable tension is not present at the pulley. A broken cable, for example, will create a situation where there is no cable tension between a plurality of cable pulleys, the lack of cable tension moves the mechanical cam style linkage to engage the braking members.

主权项

1. A lift, comprising:
a first mast stage and a second mast stage adjoining the first mast stage, the first mast stage being arranged to extend to move upwardly in a first direction relative to the second mast stage; a cable for moving the first mast stage upward relative to the second mast stage; a pulley interfaced with the cable; a spring-loaded pulley mount mounted to a supporting mast stage, the supporting mast stage being one of the first mast stage and the second mast stage, the pulley being directly mounted to the spring-loaded pulley mount, the pulley moving from a first position relative to the supporting mast stage to a second position relative to the supporting mast stage when tension from the cable is removed; and a brake mechanically coupled with the spring-loaded pulley mount by a mechanical linkage such that movement of the spring-loaded pulley mount from the first position relative to the supporting mast stage to the second position relative to the supporting mast stage mechanically actuates the brake such that the brake restricts movement of the first mast stage relative to the second mast stage when the spring-loaded pulley mount is in the second position relative to the supporting mast stage, and the brake permits movement of the first mast stage relative to the second mast stage when the spring-loaded pulley mount is in the first position relative to the supporting mast stage, the brake including a first cam attached to the first mast stage or the second mast stage, the first cam being engaged with a first engagement surface of the other of the first mast stage or the second mast stage when the spring-loaded pulley mount is in the second position relative to the supporting mast stage so as to restrict relative movement between the first mast stage and the second mast stage, the first engagement surface being parallel to the first direction.