GB2030536A

GB2030536A - Counterweight removal system

Info

Publication number: GB2030536A
Application number: GB7930618A
Authority: GB
Original assignee: Coles Cranes Ltd
Current assignee: Coles Cranes Ltd
Priority date: 1978-09-05
Filing date: 1979-09-04
Publication date: 1980-04-10
Also published as: GB2030536B

Abstract

A counterweight 34, on the rear of a crane jib superstructure 22, is mounted so that it can be moved inwardly and outwardly relative the superstructure to balance the load on the jib. During transportation the jib is folded over a platform 14, of the vehicle and the counterweight is removed from the crane and carried on the vehicle platform. To remove the counterweight, the superstructure is slewed to bring the counterweight to a position adjacent an upwardly inclined surface 36, carried by the platform of the vehicle, the bottom surface 42, of the counterweight being inclined at a corresponding angle to the horizontal equal to that of the inclined surface. The counterweight is then moved to engage the underside of the counterweight with the inclined surface on the platform and cause the counterweight to "ride up" the inclined surface of the block. In this position, the load on the beams carrying the counterweight is removed so that the counterweight can be removed and tied to the vehicle platform for travel. <IMAGE>

Description

SPECIFICATION Counterweight removal system This invention relates to cranes and in particular to mobile cranes, i.e. cranes in which the crane jib is mounted on a platform or deck of a road vehicle to enable the crane to be transported from one working site to another.

One type of such crane has a counterweight which is mounted on a beam assembly at the rear end of the crane superstructure. The beam assembly and counterweight is movable out from or towards the superstructure by the use of hydraulic rams or the like to balance the jib under varying loads.

When such a crane is to be driven along a road, the jib is folded down over the deck or platform of the vehicle and secured thereto and it is desirable for the couterweightto be removed from the superstructure and secured to the vehicle, not at one end, but rather in a position where its weight can better be carried by the vehicle suspension. Hitherto, in order to remove the counterweight from the beam, it has been necessary first to contract the beam towards the crane superstructure. Then, by using a vertically acting hydraulic ram to support the counterweight whilst it is unbolted from the beam and finally using the "vertical" hydraulic ram, to lower the counterweight to the deck of the vehicle where it is secured for travel.

This previously proposed system requires two degrees of movement and hence two rams or sets of rams, namely an "in" movement of the beam and a "down" movement of the counterweight. Similarly for reattachement, the counterweight has had to be lifted up and secured to the beam and the beam then moved in towards the crane superstructure.

It is therefore an object of the invention to simplify the removal and reattachement of the counterweight whilst still allowing the counterweight to be fixed to a desired position on the vehicle.

According to the invention there is provided a method of preparing a mobile crane for travelling from one working site to another in which the superstructure is slewed to position a counterweight attached to the superstructure by an extensible beam assembly adjacent an upwardly inclined surface formed on or carried by the platform or deck of the vehicle, the undersurface of the counterweight being inclined at a substantially equal angle to the horizontal to that of the upwardly inclined surface, and the counterweight is then moved by the beam assembly so that the upwardly inclined surface on the platform or deck and the undersurface of the counterweight engage and the counterweight is caused to ride up the upwardly inlcined surface and be supported thereon, whereupon the counterweight can be detached from the beam assembly and tied down for travelling.

Once the counterweight has been detached in this way, the superstructure and jib are, if necessary, slewed to a position for travelling and the jib is then folded down to its travelling position and secured to the deck or platform of the vehicle.

To reattach the counterweight, the beam assembly when the crane reaches the new site, the procedure is reversed. Thus, the end of the beam assembly is positioned over the counterweight and resecured thereto. Then the beam and/or superstructure is operated to slide the counterweight down from the inclined surface.

It will be appreciated that only the hydraulic rams are needed to operate the beam are required and that no ram to lift the counterweight "up and down" is needed.

If, as is desirable, the counterweight is bolted to the end of the beam, then the movement of the counterweight up the inclined surface relieves the bolts from load enabling them readily to be removed and later reinserted in their connecting position.

Also according to the invention, there is provided a mobile crane which has a counterweight which is carried by a beam assembly and which is movable inwardly and outwardly relative the jib superstructure to assist in balancing the load on the jib, a surface inclined to the horizontal on or carried by the deck or platform of the vehicle for supporting the counterweight during travelling, the counterweight having an undersurface which is inclined to the horizontal at substantially the same angle as the inclined surface on the deck or platform, the end surface on or carried by the deck or platform being positioned and arranged so as to be able to engage the underside of the counterweight upon movement of the beam assembly after the superstructure has been slewed to an appropriate position, continued movement of the beam assembly causing the counterweight to ride up the said surface.

Preferably, the inclined surface of the vehicle is provided on a reaction block, removably mounted on a seat on the deck or platform of the vehicle.

In one preferred embodiment of the invention, the beam assembly is movable to move the counterweight along a path which is inclined to the horizontal at an angle substantially equal but in opposite sense to the upwardly inclined surface. This has the advantage that the angle of the underside of the counterweight to the horizontal can be kept reasonably small so that during travel from one site to another there is not too much tendency for the counterweight to slip yet at the same time there is relatively quick clearance of the counterweight from the inclined surface during reattachement of the counterweight to the beam assembly.

The angle of the inclined surface to the horizontal may conveniently be about 3 .

The invention will now be described, byway of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of one embodiment of mobile crane in accordance with this invention showing its jib folded down for travel; Figure 2 is a diagram of part of the crane shown in Figure 1 showing the extendable beam assembly and counterweight; Figure 3 is a plan diagram of the beam assembly and counterweight; Figure 4 is a view similar to Figure 2 but showing the counterweight engaged with a block on the deck or platform of the vehicle; Figure 5 is a view similar to Figure 2 showing the counterweight secured for travel; and Figure 6 is a view similar to Figure 5 showing a modified embodiment in which an additional counterweight is provided.

The mobile crane shown in Figure 1 comprises a vehicle 12 provided with a deck or platform 14 mounted on wheels 16 to enable the vehicle to b driven along a road or the like. The platform 14 carried a conventional crane jib 18 which is shown in Figure 1 in its folded-down position ready for travel.

The jib is mounted on a turntable 20 together with superstructure 22 extending horizontally out from the turntable as can be seen in Figure 1.

The superstructure 22 carries a beam assembly, the beams 24 (see Figures 2 to 6) of which are movable from the position shown in Figures 1 and 2 in which they are substantially contracted within the superstructure 22 to an extended position shown in Figure 4. The beams 24 are moved by a pair of hydraulic rams 26, one for each beam, positioned within the superstructure and connected between a block 28 of the superstructure and a lug 30 attached to the inner end of the beam 24. The beams 16 slide in bearings 32 carried by the superstructure and similar bearings in the blocks 28.

As best shown in Figure 3, there are a pair of beams 24, one extending out from each side of the superstructure 22 and connected to the outer ends 33 of these beams is a removable counterweight 34.

In use, this counterweight can therefore be positioned outwardly, from the superstructure 22 at varying distances by extension or contraction of the rams 26 to balance the jib under varying loads. The counterweight 34 has upwardly extending flanges 45 which are bolted to the ends 33 of the beams 24 by means of bolts 44 which pass through slots 46 in the flanges and holes 48 in the beams.

When it is desired to move the crane from one operating site to another, the beams 24 are contracted to the position shown in Figure 2 by extension of the rams 26 and the jib and superstructure is then slewed to the position shown in Figure 2. In this position, the counterweight 34 is located adjacent to and in line with an inclined surface 36 of a reaction block 38 which is removably mounted in a seat 40 secured to the deck or platform 14 of the crane vehicle. As will be seen, the angle 0 by which the said surface 36 is inclined to the horizontal and which, may for example, by about 3" corresponds with the angle at which the bottom surface 42 of the counterweight also extends to the horizontal.This angle H is also the angle at which the movable beams 24 extend to the horizontal but in a sense opposite to that at which the surfaces 36 and 42 are inclined.

Once in this position the rams 26 are contracted causing the beams 24 and hence the counterweight to move outwardly relatively to the superstructure 22. The surface 42 and 36 engage and then as shown in Figure 4the counterweight rides up over the block and so becomes supported thereby.

In this position, the bolts 44 which connect the counterweight to the ends of the beams 24 are relieved of their load and so they can readily be removed. The counterweight is then tied down or secured to the deck 14.

After removal of the counterweight, the beams 24 are contracted towards the superstructure 22 by extension of the rams 26 to the position shown in Figure 5 so enabling the jib then to be slewed to the position shown in Figure 1 at which it can be secured in a stable position for travel.

As can be seen in Figure 1, the seat 40 for the counterweight, is secured to the deck or platform 14 of the crane vehicle at an appropriate desired position so that the counterweight can readily be supported during travel with a balanced axle loading.

When the crane reaches a new site and the jib is again erected, the jib will then be slewed through approximately 180"from the position shown in Figure 1 to the position shown in Figure 5 at which the ends of the beam are again positioned adjacent the counterweight. The beam assembly is then extended out from the superstructure 22 by operation of the rams 26 to a position similar to that shown in Figure 4 and the bolts 44 are then secured through the slots 46 in the counterweight and corresponding holes 48 in the outer ends 33 of the beams.

The beams 24 are then again contracted into the superstructure by extension of the rams 26, causing the counterweight 34 to slide off from its block 38 ready for use.

In the modification shown in Figure 6, the beams 14 carry an additional fixed counterweight 50 which extends across the rear ends 33 of the two beams 24 to provide additional balance weight. This additional counterweight 50 will not normally be removed during travel but will remain attached to the beams in the position indicated by the broken lines in Figure 1.

Equally, a combined counterweight can be carried beneath the beams and removed therefrom by use of the invention.

The invention has the advantage, not only of avoiding the need for two sets of hydraulic rams, but also of enabling the counterweight to be detached from the beam and reattached when necessary in a fast and convenient manner.

Claims

1. A method of preparing a mobile crane for travelling from one working site to another in which the jib superstructure is slewed to position a counterweight attached to the superstructure by an extensible beam assembly adjacent an upwardly inclined surface formed on or carried by the platform or deck of the vehicle, the undersurface of the counterweight being inclined at a substantially equal angle to the horizontal to that of the upwardly inclined surface, and the counterweight is then removed by the beam assembly so that the upwardly inclined surface on the platform or deck and the undersurface of the counterweight engage and the counterweight is caused to ride up the upwardly inclined surface and be supported thereon, whereupon the counterweight can be detached from the beam assembly and tied down for travelling.

2. A method as claimed in Claim 1, in which after detachment of the counterweight, the superstructure and jib are slewed to a position for travelling and the jib is folded down and secured to the deck or platform of the vehicle.

3. A method as claimed in Claim 1 or Claim 2, in which the counterweight is attached to the beam assembly by bolts and the movement of the counterweight as it rides up the upwardly inclined surface relieves the bolts of load thereby enabling them to be readily removed to release the counterweight from the beam.

4. A method as claimed in any preceding claim, in which the beam assembly is movable to move the counterweight along a path which is inclined to the horizontal at an angle substantially equal but in the opposite sense to the upwardly inclined surface.

5. A method of preparing a mobile crane for travelling from one working site to another, substantially as herein described with reference to Figures 1 to 5, or to Figure 6 of the accompanying drawings.

6. A mobile crane which has a counterweight which is carried by a beam assembly and which is movable inwardly and outwardly relative to the jib superstructure to assist in balancing the load on the jib, a suface inclined to the horizontal on or carried by the deck or platform of the vehicle for supporting the counterweight during travelling, the counterweight having an undersurface which is inclined to the horizontal at substantially the same angle as the inclined surface on the deck or platform, the said surface on or carried by the deck or platform being positioned and arranged so as to be able to engage the underside of the counterweight upon movement of the beam assembly after the superstructure has been slewed to an appropriate position, continued movement of the beam assembly causing the counterweight to ride up the said surface.

7. A mobile crane as claimed in Claim 6, in which the beam assembly includes a pair of beams one on either side of the superstructure which can be together moved inwardly and outwardly relative the superstructure by means of hydraulic rams, the counterweight being attached to the outer ends of the two beams.

8. A mobile crane as claimed in Claim 7, in which the counterweight is attached to the beams by bolts which pass through a hole in one of the counterweight and beam and a slot in the other of the counterweight and beam.

9. A mobile crane as claimed in Claim 7 or Claim 8 in which the beams are carried by the superstructure so as to be movable along a path which is inclined to the horizontal at an angle substantially equal but in the opposite sense to the said surface.

10. A mobile crane as claimed in any of the claims 6 to 9, in which the inclined surface of the vehicle is provided on a block removably mounted on the deck or platform of the vehicle.

11. A mobile crane as claimed in any of claims 6 to 10, in which the said surface and the underside of the counterweight are at an angle to the horizontal of about 3".

12. A mobile crane substantially as herein described with reference to Figures 1 to 5, or to Figure 6, of the accompanying drawings.