Method and apparatus for lifting loads step-by-step, especially heavy loads

• US 3,881,687 A
• Filed: 04/27/1973
• Issued: 05/06/1975
• Est. Priority Date: 05/04/1972
• Status: Expired due to Term

• Current Assignee: AB Resmastservice Mariestadsvagen
• Original Assignee: Dag Valdemar Henry Johansson
• Inventors: Johansson, Dag Valdemar Henry
• Primary Examiner(s): Smith, Al Lawrence
• Assistant Examiner(s): Watson, Robert C.
• Application Number:
  US05/354,936
• Time in Patent Office: 739 Days
• Field of Search: 254/89R,89H,105,108-111
• US Class Current: 254/1
• CPC Class Codes: E02B 17/0836 with climbing jacks climbing cranes B66C23/32; hydraulic lifting jacks B66F3/24 and subgroups
• CPC Class Codes: E02B 17/0863 with rack and pawl mechanism

Abstract

A stepwise lifting device has at least one profiled beam having two opposing side walls with an open channel therebetween, and a conventional lifting jack is accommodated in the channel and has a base portion and an extendable lifting portion with a thrust head attached thereto. Uniformly spaced along the side walls of the profiled beam are grooves, the top and bottom surfaces of which slope upwardly. First and second jack supporting elements are provided for insertion between the grooves during a jack lifting and lowering operation, the arrangement being such that the weight of the jack is taken alternately on said elements during upward and downward stepping of the jacks. Means are also provided for moving the supporting elements into and out of successive grooves as the lift ascends or descends.

Claims

1. A device for lifting loads in stages comprising at least one jack having a base portion and an extendable and retractable lifting portion, a carrying structure for said jack having two opposing side walls spaced from each other and defining a jack receiving channel therebetween, said side walls having inside surfaces, first and second jack supporting means each extending across the channel between the opposing side walls to alternately support said base portion and said lifting portion of said jack respectively, and a plurality of generally horizontal abutment surfaces disposed in the opposing side walls and spaced along the length of said carrying structure, said plurality of abutment surfaces being inclined downwards from the inside surfaces in the opposing side walls, portions of said jack supporting means selectively engaging and co-acting with said abutment surfaces in the opposing side walls and having an equivalent chamfer to match said inclined abutment surfaces to suPport said jack centrally within the jack receiving channel of said carrying structure and free from contact therewith.

2. A device for lifting loads as claimed in claim 1 wherein said carrying structure is a U-beam with a length at least equal to the distance the load is to be lifted, and said opposing side walls of said carrying structure include oppositely located horizontal grooves, the lower surfaces of which form said generally horizontal abutment surfaces.

3. A device for lifting loads as claimed in claim 2 wherein said first and second jack supporting means have the form of plates, capable of being inserted into and retracted from said grooves to alternately support said base portion and said lifting portion of said jack during load lifting and lowering sequences.

4. A device for lifting loads as claimed in claim 3 wherein said lifting portion of said jack has a head portion, and the second jack supporting plate has a notch accommodating said lifting portion so that said second jack supporting plate may support said lifting portion by supporting said head portion.

5. A device for lifting loads as claimed in claim 3, wherein holders are attached to the base portions and lifting portions of said jack to receive said first and second supporting means when they are retracted from the grooves in said U-beam.

6. A device for lifting loads as claimed in claim 2, wherein at least one of said first and second jack supporting means is detachably fastened to its jack and has two jaws which move outwardly in opposite directions to engage said grooves in said side walls to support said jack, and each jaw is biased toward an outwardly projecting position by a spring.

7. A device for lifting loads as claimed in claim 6, wherein a hydraulically operated piston and cylinder device is arranged to oppose the bias of the springs in said jaws to retract said jaws.

8. A device for lifting loads as claimed in claim 6, wherein each jaw includes a generally horizontal lower surface to act as a supporting surface for said jaw, and each jaw further includes a canted, inwardly sloping upper surface to co-act with the upper edge of said grooves to force said jaw inward during an upward movement of said jack supporting means.

9. A device for lifting loads comprising at least one jack having a base portion and an extendable and retractable lifting portion;

a carrying structure for said jack having two opposing side walls defining a jack receiving channel therebetween;

first and second jack supporting means to alternately support said base portion and said lifting portion of said jack respectively; and

a plurality of generally horizontal abutment surfaces disposed in the opposing side walls of said carrying structure receiving said jack supporting means and cooperating therewith to support said jack centrally within the jack receiving channel of said carrying structure and free from contact therewith;

said carrying structure being a U-beam with a length at least equal to the distance the load is to be lifted;

said opposing side walls of said carrying structure including oppositely located horizontal grooves, the lower surfaces of which form said generally horizontal abutment surfaces;

said first and second jack supporting means having the form of plates, capable of being inserted into and retracted from said grooves to alternately support said base portion and said lifting portion of said jack during load lifting and lowering sequences;

said opposing side walls having inside surfaces;

said abutment surfaces in said side walls of said carrying structure being inclined downward from the inside surfaces of the side walls; and

the portions of said jack supporting means co-acting with said abutment surfaces having an equivalent chamfer to match said inclined abutment surfaces.

10. A device for lifting loads in stages comprising at least one jack having a base portion and an extendable And retractable lifting portion, a carrying structure for said jack having opposing side walls defining a jack receiving channel therebetween;

a first jack supporting means in the form of a plate to support said base portion in said carrying structure and a second jack supporting means for supporting said lifting portion in said carrying structure, said second jack supporting means being formed by a head member of said lifting portion;

said carrying structure comprising a number of U-shaped sections having opposing side walls and being placeable one on top of another into a stack to form a U-beam structure, each section being of a length less than the possible length of extension of said jack;

each of said sections having on the inner surface of each of said opposing side walls a substantially horizontal groove, the groove on each wall being opposite the groove of the other wall;

opposite side edges of said first jack supporting means being insertable into said grooves in said side walls, the lower edges of said grooves being inclined downwards from the inner surfaces of said side walls to co-operate with corresponding chamfers on said opposite side edges; and

the top edge of the topmost of said U-shaped sections in said stack forming a substantially horizontal abutment surface for said head member of said lifting portion.

11. A method of lifting a load, step by step, by a jack having a base portion and an extendable and retractable lifting portion, and an upright jack carrying structure having opposite side walls spaced from each other and defining a jack receiving channel therebetween, said side walls including inside surfaces and being provided with a plurality of horizontal grooves spaced along the length of the carrying structure, each groove having a corresponding groove on the opposite side wall, the lower side surface of said groove inclining downwards from the inside surfaces of said side walls, said method comprising the steps of engaging portions of a first jack supporting means to the inclining side surfaces of a first pair of opposed grooves in said opposite side walls, the portions of said first jack supporting means having a chamfer corresponding to the inclining side surfaces of the first pair of grooves, centering said jack between and spaced from the opposite side walls such that said jack is supported from its base portion on said first jack supporting means engaged to the first pair of grooves, extending the lifting portion of the jack to raise a load on the lifting portion thereof, engaging portions of a second jack supporting means to the inclining side surfaces of a second pair of opposed grooves in said opposite side walls and above said first pair, the portions of said second jack supporting means having a chamfer corresponding to the inclining side surfaces of the second pair of grooves, and said second jack supporting means being constructed to engage said lifting portion of said jack, retracting the jack so that said lifting portion of said jack rests on said second jack supporting means, continuing the retraction of the jack so that the jack is suspended from the portions of said second jack supporting means engaged to the inclining side surfaces of said second pair of opposed grooves and said base portion is lifted away from said first jack supporting means while the load is still on the lifting portion of said jack, and re-engaging the portion of said first jack supporting means to the inclining side surfaces of a third pair of grooves in said opposite side walls and the third pair being intermediate the first and second pairs of opposed grooves so that upon renewed extension of the jack the base portion of the jack will be supported by said first jack supporting means whereby the centered jack and the load on said jack is lifted step by step relative to said carrying structure without adversely affecting the centered jack and the load thereon.