Hoist with redundant safety features

Claim 1

A hoist with redundant safety features comprising: a hoist support frame; lifting drum means mounted on said hoist support frame; means for rotating said lifting drum means; brake means for stopping the rotation of said lifting drum means; load block assembly means; equalizer assembly means mounted on said hoist support frame; a first set of ropefalls and a second set of ropefalls; and an alarm; said load block assembly means being suspended by said first set of ropefalls and said second set of ropefalls, each of said ropefalls having one end secured to said lifting drum means and the other end secured to said equalizer assembly means, each of said sets of ropefalls having sufficient load bearing capacity to carry the load carried by the other set of ropefalls in addition to its own load; each of said ropefalls having first sections extending from said lifting drum means to said load block assembly means and second sections extending from said load block assembly means to said equalizer assembly means, each of said first sections being positioned in a substantially common plane with each other, and each of said second sections being positioned in another substantially common plane with each other; said equalizer assembly means including first means for balancing the load carried by said first set of ropefalls, second means for balancing the load carried by said second set of ropefalls, and load sensor means for generating an electrical signal in response to variations in the load carried by said first or said second set of ropefalls, said electrical signal being adapted for activating said brake means and/or activating said alarm, said equalizer assembly including equalizer support means mounted on said hoist support frame, said first means for balancing the load comprising a first ropefall support member pivotally mounted on said equalizer support means, the other ends of the ropefalls of said first set of ropefalls being secured to said first ropefall support member, said second means for balancing the load comprising a second ropefall support member pivotally mounted on said equalizer support means, the other ends of the ropefalls of said second set of ropefalls being secured to said second ropefall support member, said load sensor means comprising a first load sensor mounted on said equalizer support means adapted to sense the load carried by said first ropefall support member and to generate said electrical signal when said load carried by said first ropefall support member is varied beyond a predetermined level, and a second load sensor mounted on said equalizer support means adapted to sense the load carried by said second ropefall support member and to generate said electrical signal when said load carried by said second ropefall support member is varied beyond a predetermined level, said equalizer support means comprising trunnion means pivotally mounted on said hoist support frame; an inner support member mounted on said trunnion means and extending downwardly from said trunnion means, said second ropefall support member comprising a second support beam pivotally depending from said inner support member; an outer support member mounted on said trunnion means and extending coaxially with said inner support member downwardly from said trunnion means, said first ropefall support member comprising a first support beam pivotally depending from said outer support member; the other ends of the ropefalls of said first set of ropefalls being secured to said first support beam, the other ends of the ropefalls of said second set of ropefalls being secured to said second support beam.