Hydraulic lift mechanism

Claim 2

A telescopic fluid operated hoist comprising: a plurality of open ended barrels of successively smaller diameter with smaller barrels movably fitted within successively larger barrels, a plurality of pistons of successively smaller diameter for coupling to the bottom open end of corresponding size barrels supporting successively smaller barrels and defining expansion chambers between adjacent pistons and having means for fluid communication between said expansion chambers, a plurality of headers of successively smaller diameter for coupling to corresponding size barrels above corresponding size pistons positioned between adjacent barrels, a shoulder on the outside of all but the largest barrel defining with the header coupled to an adjacent larger barrel a retraction chamber therebetween, said barrels having means for fluid communication between said retraction chambers, first and second inlet means coupled to the largest piston for fluid communication between a fluid pressure source and said expansion and retraction chambers respectively, and wherein said barrels are generally circular in cross-section and are nonconcentrically fitted within each other to prevent rotation therebetween by nonconcentric shaped headers with said shoulders shaped to match generally the shape of said nonconcentric headers.

Claim 3

The hoist of claim 1 wherein said barrels and said nonconcentrically shaped headers are aligned relative to each other such that the thickest portions of the barrels and headers are positioned to the same side increasing the structural strength of the hoist.

Claim 4

A telescopic fluid operated hoist comprising: a plurality of open ended barrels of successively smaller diameter with smaller barrels movably fitted within successively larger barrels, a plurality of pistons of successively smaller diameter for coupling to the bottom open end of corresponding size barrels supporting successively smaller barrels and defining expansion chambers between adjacent pistons and having means for fluid communication between said expansion chambers, a plurality of headers of successively smaller diameter for coupling to corresponding size barrels above corresponding size pistons positioned between adjacent barrels, a shoulder on the outside of all but the largest barrel defining with the header coupled to an adjacent larger barrel a retraction chamber therebetween, said barrels having means for fluid communication between said retraction chambers, and first and second inlet means coupled to the largest piston for fluid communication between a fluid pressure source and said expansion and retraction chamber respectively, said means for fluid communication between said expansion chambers including bores providing passageways from below larger pistons to above adjacent smaller pistons and wherein said firsT inlet means includes a fluid conduit coupled to the bore in the largest piston, said means for fluid communication between said retraction chambers including holes in the walls of all but the largest barrel providing passageways between said retraction chambers and an interior chamber in the smallest barrel defined by a plug capping the upper open end of the barrel and the piston coupled to the smallest barrel, said second inlet means includes a telescoping multi-stage fluid conduit extending through said pistons into said interior chamber for coupling to a fluid source at a position adjacent said first inlet means for fluid communication between a fluid source and said interior chamber throughout expansion and retraction of said barrels, including a check valve positioned in said interior chamber coupled to a bore through the smallest piston and a venting valve coupled to said plug capping said interior chamber, said venting valve being open during initial filling of said system with a fluid introduced through said inlet means forcing unwanted fluids from said expansion chambers through said check valve into said interior chamber and with a fluid introduced through said second inlet means forcing unwanted fluids in said interior chamber through said venting valve thereby purging the hoist of unwanted fluids.

Claim 5

A telescopic fluid operated hoist comprising: a plurality of open ended barrels of successively smaller diameter with smaller barrels movably fitted within successively larger barrels, a plurality of pistons of successively smaller diameter for coupling to the bottom open end of corresponding size barrels supporting successively smaller barrels and defining expansion chambers between adjacent pistons and having means for fluid communication between said expansion chambers, a plurality of headers of successively smaller diameter for coupling to corresponding size barrels above corresponding size pistons positioned between adjacent barrels, a shoulder on the outside of all but the largest barrel defining with the header coupled to an adjacent larger barrel a retraction chamber therebetween, said barrels having means for fluid communication between said retraction chambers, and first and second inlet means coupled to the largest piston for fluid communication between a fluid pressure source and said expansion and retraction chamber respectively, said means for fluid communication between said expansion chambers including bores providing passageways from below larger pistons to above adjacent smaller pistons and wherein said firsT inlet means includes a fluid conduit coupled to the bore in the largest piston, said means for fluid communication between said retraction chambers including holes in the walls of all but the largest barrel providing passageways between said retraction chambers and an interior chamber in the smallest barrel defined by a plug capping the upper open end of the barrel and the piston coupled to the smallest barrel, said second inlet means includes a telescoping multi-stage fluid conduit extending through said pistons into said interior chamber for coupling to a fluid source at a position adjacent said first inlet means for fluid communication between a fluid source and said interior chamber throughout expansion and retraction of said barrels, including a check valve positioned in said interior chamber coupled to a bore through the smallest piston and a venting valve coupled to said plug capping said interior chamber, said venting valve being open during initial filling of said system with a fluid introduced through said inlet means forcing unwanted fluids from said expansion chambers through said check valve into said interior chamber and with a fluid introduced through said second inlet means forcing unwanted fluids in said interior chamber through said venting valve thereby purging the hoist of unwanted fluids.

Claim 6

A telescopic fluid operated hoist comprising: a plurality of barrels of successively smaller dimensions with smaller barrels interfitted within larger barrels allowing movement relative to each other for expanding and retracting said hoist, means for defining expansion chambers between adjacent barrels and for establishing fluid communication between said chambers, said expansion chambers having lift areas on which fluid pressure introduced therein acts to move the barrels of said hoist, each of said barrels being eccentrically mounted in said next larger barrels such that rotation of a smaller barrel within a larger barrel is precluded.

Claim 7

A telescopic fluid operated hoist comprising: a plurality of barrels of successively smaller dimensions with smaller barrels interfitted within larger barrels allowing movement relative to each other for expanding and retracting said hoist, means for defining expansion chambers between adjacent barrels and for establishing fluid communication between said chambers, said expansion chambers having lift areas on which fluid pressure introduced therein acts to move the barrels of said hoist, each of said barrels being eccentrically mounted in said next larger barrels such that rotation of a smaller barrel within a larger barrel is precluded.

Claim 8

The hoist of claim 4 said barrels having headers confining the outer surfaces of the next smaller barrels, said next smaller barrels being eccentric to said confining headers.