Mobile aerial hoist

Claim 1

A hoist for controllably lifting, holding or lowering objects adapted for use with a mobile aerial device having an articulated or extendable boom supporting a man-lifting platform for overcenter operation, which comprises: (a) a hoist mounting shaft, adapted for securement to said boom in proximity to said platform; (b) a hoist housing, adapted to be rotatably positioned about said shaft; (c) a positioning plate, adapted to be rotatably positioned about said shaft in close alignment to said housing; (d) a first means to manually secure said housing to said positioning plate in a plurality of rotatable positions exceeding 90 degrees of rotation about said mounting shaft in relation to said boom; (e) a drum, adapted to be controllably rotated about said shaft; (f) an elongated jib adapted to be linearly received and positioned in said housing; (g) a second means to secure said jib to said housing in a plurality of linear positions; (h) a pair of sheaves rotatably secured near one end of said jib; (i) a load lift line, adapted to be secured at one end about said drum in a manner to extend or retract as said drum is rotated, said line extending between said sheaves in a manner to rotate about one sheave during non-overcenter operation, and about the other sheave during overcenter operation, said line adapted for connection to the object to be lifted, held or lowered; (j) a linearly extendable fluid device pivotally mounted to said boom and said positioning plate, said linearly extendable fluid device being operative to position and secure said positioning plate in plurality of positions of less than 90 degrees of rotation about said mounting shaft in relation to said boom; (k) a rotating fluid device, adapted to controllably rotate or secure said drum in relation to said shaft, to selectively extend or retract said line; (l) a first fluid control means adapted to actuate said linearly extendable fluid device; (m) a second fluid control means adapted to actuate said rotating fluid device wherein said jib may be linearly positioned and secured in relation to said housing from said man-lift platform, said jib may be manually rotatably positioned in one 90° quadrant for non-overcenter operation and in another 90° quadrant for overcenter operation, and secured in position, the second fluid control means may be actuated from said platform to rotate said drum to extend or retract said line in a manner to lift, hold or lower an object in proximity to said man-lifting platform and said linearly extendable fluid device may be actuated by said first fluid control means to raise or lower said jib; (n) said first means to manually secure said housing to said positioning plate comprises an aperture in said housing adapted to receive a pin therethrough, a plurality of spaced apertures in said positioning plate, adapted to rotatably align and receive said pin extending through said housing, to selectively secure said housing in any one of plurality of rotatable positions for non-overcenter or overcenter operation; and (o) said first and second fluid control means includes complimentary opposing control handles extending above and below the profile of the upper boom tip for ease of access by a worker in said platform when said boom is articulated into an overcenter position.