US 4,068,825 AGranted

Double parallelogram jack

OwnerRoger Macphersoninventor

Life of this patent

Estimating the term…

Loading patent…

Abstract

A load-bearing plate is mounted by a plurality of pivotal links above a base plate, and solely for vertical movement toward and away from the base plate. An intermediate frame including two, spaced, parallel side bars is supported by the links between the two plates for swinging movement on the base plate about a pair of spaced, parallel axes. Driving means, such as a hydraulic screw jack is mounted between the two side bars for swinging movement therewith, and has a reciprocable piston rod attached to one of two, parallel shafts mounted at opposite ends in slots in the side bars to reciprocate longitudinally of the bars during the raising and lowering of the load-bearing plate. The reciprocable movement of the two shafts oscillates the links which in turn cause the load-bearing plate to reciprocate only vertically relative to the base plate.

Claims10

Dependent claims

A jack, comprising

a base,
an intermediate frame,
a first plurality of links pivotally connected to said base and said frame to support said frame on said base for translational movement in an arc about a pair of spaced axes and between first and second limit positions,
a load-bearing member,
a second plurality of links pivotally connected to said frame and said load-bearing member to support said load-bearing member on said frame for movement relative thereto,
drive means mounted on said frame for arcuate movement therewith and having a reciprocable driver,
a third plurality of links pivotally connected to said frame and to at least certain of said first and second pluralities of links for translational movement with said frame relative to said base and said load-bearing member, and
means pivotally connecting said third plurality of links to said driver and operative to impart said arcuate movement to said frame, and to reciprocate said load-bearing plate linearly toward and away from said base plate upon reciprocation of said driver.

5 more elements

A jack, comprising

a pair of rigid plates,
a first plurality of pivotal links interposed between said plates for supporting one plate movably above the other,
a pair of spaced, parallel side members positioned between said plates and having a first pair of spaced, parallel pins extending transversely therebetween, and slidable at opposite ends thereof in elongate slots formed in said side members adjacent opposite ends thereof,
drive means mounted on said side members between said plates and having a drive element reciprocable selectively in opposite directions between a retracted and an extended position,
means connecting said drive element to one of said pins to impart reciprocation thereto, and
a second plurality of pivotal links connecting said pins to said first plurality of links to impart pivotal movement thereto,
said links being operative during pivotal movement thereof to swing said side members about a first pair of spaced, parallel axes fixed with respect to said other plate, and about a second pair of spaced, parallel axes fixed with respect to said one plate and movable with said one plate in spaced, parallel planes containing said first pair of axes, whereby said one plate is moved linearly between raised and lowered positions with respect to said other plate.

4 more elements

Dependencies are inferred from the claim text.