Vehicle doorway lift

Claim 2

A lift assembly for use in connection with a recessed opening forming part of the doorway of a vehicle having a floor surface, comprising: a pair of substantially vertically movable lifting columns associated with the vehicle and positioned at the opening; first means associated with the vehicle for controllably raising and lowering said lifting columns; second means fixed to the vehicle for guiding the lifting columns as they move substantially vertically between raised and lowered positions; a platform disposed in the opening and comprising a linear assembly of alternating tread and riser plates interconnected by hinge means in end-to-end arrangement, said platform being connected to the bases of the lifting columns at its inner edge portion by hinge means whereby the inner end of the platform is thereby suspended; third means, pivotally connected with the outer edge portion of the platform and with the lifting columns, said third means being operative to suspend the outer end of the platform from said lifting columns; and fourth means, pivotally connected with the outer edge portion of the platform and with the lifting columns, for extending and contracting the assembly of plates between a flat horizontal configuration level with the floor surface and a step-like configuration within the opening and for retaining said plates in each of said configurations when required; whereby extension of said fourth means in combination with rotation of the third means about its pivot connections with the lifting columns forces the plates from the step-like configuration to the flat horizontal configuration, and whereby subsequent lowering of the lifting columns results in lowering of the flat horizontal platform to grade and subsequent raising of the lifting columns results in raising of said platform to the floor level, and whereby contraction of said fourth means in combination with downward rotation of the third means forces the plates from the flat horizontal configuration to the step-like configuration.

Claim 3

A lift assembly for use in connection with a recessed rectangular opening forming part of the doorway of a vehicle having a floor surface, comprising: a pair of substantially vertically disposed guide members fixed to the vehicle and positioned at the inner corners of the opening; a pair of movable lifting columns, one such lifting column being associated with each guide member so as to be slidable therealong; means associated with the vehicle for raising and lowering the columns together when actuated so they may be moved up and down within the opening between raised and lowered positions; a platform disposed in the opening and comprising a linear assembly of alternating tread and riser plates interconnected by hinge means in end-to-end arrangement, the innermost plate, being a riser plate, being connected to the base portions of the lifting columns at its inner edge portion by hinge means whereby the inner end of the platform is thereby suspended; a pair of tension members, each such tension member extending downwardly and angularly between and being pivotally connected with one of the lifting columns and the outermost plate, being a tread plate, for suspending the outer end of the platform from said lifting columns at a level spaced above the connection of the innermost plate with said lifting columns; a pair of spaced hydraulic cylinders, each being pivotally connected at its inner end to the base of one of the columns and at its outer end to the outermost plate, for extending and contracting the assembly of plates between a flat horizontal configuration level with the floor surface and a step-like configuration within the opening and for retaining said plates in each of said configurations when required; whereby extension of the cylinders in combination with upward rotation of the tension members about their pivot connections with the lifting columns forces the plates from the step-like configuration to the flat horizontal configuration, and whereby subsequent lowering of the lifting columns results in lowering of the flat horizontal platform to grade and subsequent raising of the lifting columns results in raising of said platform to the floor level, and whereby contraction of the cylinders in combination with downward rotation of the tension members forces the plates from the flat horizontal configuration to the step-like configuration.

Claim 4

A lift assembly for use in connection with a recessed rectangular opening forming part of the doorway of a vehicle having a floor surface, comprising: a pair of substantially vertically disposed guide members fixed to the vehicle and positioned at the inner corners of the opening; a pair of movable lifting columns, one such lifting column being associated with each guide member so as to be slidable therealong; means associated with the vehicle for raising and lowering the columns together when actuated so they may be moved up and down within the opening between raised and lowered positions; a platform disposed in the opening and comprising a linear assembly of alternating tread and riser plates interconnected by hinge means in end-to-end arrangement, the innermost plate, being a riser plate, being connected to the base portions of the lifting columns at its inner edge portion by hinge means whereby the inner end of the platform is thereby suspended; a pair of tension members, each such tension member extending downwardly and angularly between and being pivotally connected with one of the lifting columns and the outermost plate, being a tread plate, for suspending the outer end of the platform from said lifting columns at a level spaced above the connection of the innermost plate with said lifting columns; a pair of spaced hydraulic cylinders, each being pivotally connected at its inner end to the base of one of the columns and at its outer end to the outermost plate, for extending and contracting the assembly of plates between a flat horizontal configuration level with the floor surface and a step-like configuration within the opening and for retaining said plates in each of said configurations when required; whereby extension of the cylinders in combination with upward rotation of the tension members about their pivot connections with the lifting columns forces the plates from the step-like configuration to the flat horizontal configuration, and whereby subsequent lowering of the lifting columns results in lowering of the flat horizontal platform to grade and subsequent raising of the lifting columns results in raising of said platform to the floor level, and whereby contraction of the cylinders in combination with downward rotation of the tension members forces the plates from the flat horizontal configuration to the step-like configuration.

Claim 5

The lift assembly as set forth in claim 2 comprising: a slotted bracket and pin assembly interconnecting each hydraulic cylinder with the platform between the latter's ends to assist in maintaining the platform in a substantially flat, horizontal configuration when the cylinders are extended.

Claim 6

The lift assembly as set forth in claim 3 which includes gusset plates at the inner end of the outermost plate of the platform, a tread plate, such that the gusset plates abut against the next inner plate, a riser plate, to provide a rigid connection between the two.

Claim 7

The lift assembly as set forth in claim 2 wherein: said means for raising or lowering the lifting columns comprises: a lift hydraulic cylinder mounted within the vehicle; and a pair of roller chains, each being secured to the vehicle at one end and to one of the lifting columns at the other end, said roller chains being connected with the lift cylinder between their ends so that movement of the cylinder raises or lowers the lifting columns together.

Claim 8

The lift assembly as set forth in claim 5 wherein the vertically disposed guide members fixed to the vehicle and positioned at the inner corners of the opening are tubular with a lifting column running inside.

Claim 9

The lift assembly as set forth in claim 2 comprising: a safety gate pivotally mounted at the outer edge of the platform for movement between a flat position in the plane of the platform and an upraised position substantially perpendicular to the platform; and means interconnecting the lifting columns and safety gate for pivoting the latter to the upraised position when the lifting columns are initially retracted.