US 5,394,959 AGranted

Scissor lift apparatus for work platforms and the like

AssigneeSimon Aerials, Inc.

InventorsRichard E. Cullity, David P. Engvall

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Abstract

A scissors lift apparatus has three scissor units for supporting heavy loads. A central scissor unit has its arms located inwardly of the immediately lower and upper scissor units, and folds into the upper and lower scissor units for storage within a chamber in a mobiled chassis. The scissor arms of the upper and lower scissor units includes rectangular box beams with a greater vertical than horizontal dimension. Hydraulic cylinders are located within and coupled to the opposite two arms of the center scissor unit to expand and collapse the same. The mobile chassis has front steering wheels mounted with hydraulic powered-caster-type wheel drive and steering apparatus. The steering king pin is laterally offset from the vertical plane through the center of wheel. A dual fail safe braking unit on the trailing wheels has an applied hydraulic cylinder unit including a floating cylinder with a single spring applied piston and rod which is supported in a fixed journal and connected to one wheel. An internal compression spring maintains the rod extended except when over loading by hydraulic pressure. A second rod is secured to the cylinder and is releasably coupled to the second wheel.

Claims23

Dependent claims

A scissors lift apparatus for supporting of personnel in various elevated positions, comprising a base support unit, at least three scissor units mounted in vertical stacked and substantially vertically aligned relationship and including a first scissor unit having a bottom end secured to a base unit and adapted to be opened upwardly therefrom with a top end extended upwardly, a second scissor unit having a lower end with a connection to the top end of said first scissor unit and adapted to be opened upwardly therefrom with a top end of the second scissor unit extended upwardly, a third scissor unit having a lower end with a connection to the top end of the second scissor unit and having a top end, a support structure secured to the top end of the third scissor unit, each of said scissor units having a first scissor arm and a second scissor arm mounted adjacent in side-by-side orientation and pivotally connected to each other, said second scissor unit having its first and second scissor arms closely spaced and each of said first and third scissor units having said first and second scissor arms spaced laterally of each other and located to the opposite sides of said first and second scissor arms of said second scissor unit and having the ends of said scissor arms connected to form said connections of said scissor units, said first arms of said first and third scissor units and said second arms of said first and third scissor units being substantially aligned and whereby collapse of said scissor units moving and locating said first and second arms of said second scissor units between said first and second scissor arms of said first and third scissor units thereby providing a compact storage of said scissor units with said second scissor unit located in overlapping relation with both said first and third scissor units.

A multiple section scissor lift apparatus for supporting of a platform upon a base structure for selective elevation of the platform with respect to a base support structure comprising a plurality of vertically expandable and collapsible scissor units each of which includes a first and second centrally pivoted scissor arms, said plurality including at least three scissor units including a lower scissor unit and an upper scissor unit and a central scissor unit interconnecting said lower scissor unit to said upper scissor unit, said first and second scissor arms of said central scissor unit being located in adjacent close spaced relation and having exterior sides, said each of said first and second scissor arms of said lower and upper scissor units each being located in similar lateral spaced relation with a spacing of the first and second scissor arms being slightly greater than the total width of said first and second scissor arms of said central scissor unit, connections securing said first and second arms of said upper and lower scissor units to the exterior sides of said first and second arms of said central scissor unit whereby said arms of said lower and upper scissor units are located to the exterior of said exterior sides of said central scissor unit and said central scissor unit arms fold into said lower and upper scissor units in the collapsed position of said scissor lift apparatus.

A mobile lift apparatus comprising a wheeled chassis having a set of laterally spaced steering wheels and a set of laterally spaced following wheels, said sets of wheels being longitudinally spaced and mounted to said chassis, said chassis having wheel wells accommodating each of said wheels and each wheel well having an overlying horizontal top wall and an inner depending vertical sidewall to at least one side of said corresponding accommodated wheel, a central chamber including laterally spaced sidewalls located adjacent said wheels and extending downwardly below the axial of said wheels to a bottom wall to define a chamber substantially extending throughout the vertical depth of said chassis, said wheels being mounted to said corresponding vertical sidewall of said corresponding wheel well, a multiple sectioned scissors lift having at least three scissor units in vertically interconnected relationship, a lowermost unit of said scissor units mounted within said chamber adjacent to the bottom wall of said chamber and said scissor apparatus in a collapsed state located within said chamber,

a caster steering assembly secured to said chassis and connected to said steering wheels, said caster steering assembly having a kingpin unit for each steering wheel, each kingpin unit includes a kingpin pivotally mounted to said top wall of said corresponding wheel well, said kingpin having a vertical axis of rotation aligned with said wheel and with said vertical axis of rotation laterally offset outwardly of the corresponding vertical sidewall from a vertical plane through said wheel, with said wheel in a straight forward orientation.

Dependencies are inferred from the claim text.