Stackable skips

Abstract

 A stackable skip of the type comprising a four-walled, open-topped metal container whose front wall (14) is forwardly inclined, the container being adapted to be selectively mounted on a motor vehicle for the transport of materials carried by the skip by being dragged onto the rear of the transport vehicle by means of a hydraulically displaceable open hook carried by the vehicle. The skip is fitted with a closed hook (62) on its inclined front wall for engagement with the open hook on the transport vehicle, the closed hook being mounted displaceably on said inclined front wall (14), so that it can be selectively extended to a position forward of, and above the level of, the top edge of said front wall (14) of the skip. The container includes a base which is formed by a pair of side girders (18a, 18b), coupled together by cross beams (20) and covered by a steel plate (19) forming the skip floor, the side girders (18a, 18b) being arranged to extend substantially over the full length of said skip floor. The side girders (18a, 18b) supporting the skip floor comprise respective lengths of channel iron, disposed so that their respective channels both face laterally outwardly at the sides of the skip base, and wherein the side walls of the skip comprise a plurality of side beams (26) which extend upwardly at an angle to the base, the lower ends of these side beams (26) being welded to the upper surface of the lower leg of the associated side girder (18a, 18b) and the sides of these side beams being welded to the outer edge of the upper leg of the associated side girder (18a, 18b).

Description

[0001] The present invention is concerned with stackable skips of the type comprising four-walled, open-topped metal containers which are adapted to be selectively mounted on motor vehicles for the transport of materials carried by such skips.

[0002] A typical conventional skip comprises a base structure on which are rigidity mounted a pair of longitudinally extending side walls which extend generally upwardly but at an angle to the base so as to diverge outwardly. Also attached rigidity to the base structure and to the forward ends of the side walls is a front wall which is forwardly inclined relative to the base, usually at roughly the same angle to the base as the side walls. A rear wall of the container is pivotally mounted relative to the base so as to be capable of being folded down against the ground to allow easy access to the skip interior, for example by a wheelbarrow, when the skip is sitting on the ground and is to be filled.

[0003] Skips are transported between sites on the specially adapted rear chassis of motor vehicles/lorries.

[0004] The majority of conventional skips are arranged to be hoisted onto the transport vehicle by means of four chains which are attached at their one ends to four projections on the container and at their other ends to a common link carried by a hydraulic hoist on the vehicle. When the skip is to be mounted on the vehicle, the four loose ends of the chains are attached to the four projections so that the skip can be lifted and manoeuvred into position on the vehicle by the hydraulic hoist. When it is to be placed on the ground from the vehicle, the operation is reversed.

[0005] A second type of known skip is arranged to be dragged onto the rear of the transport vehicle by means of a hydraulically displaceable open hook carried by the vehicle. This open hook is carried/formed on the end of a generally L-shaped rigid arm which is pivotable in a vertical plane by a first hydraulic ram about a first horizontal axis carried by a cantilever arm, which is itself pivotable by a second hydraulic ram about a second horizontal axis, parallel to said first horizontal axis, on the vehicle chassis. By this mechanism, the hook can be hydraulically displaceable upwards and downwards, and fore and aft in relation to the vehicle chassis for dragging skips onto the chassis and displacing them off the chassis. For these purposes, the open hook carried by the transport vehicle can be manoeuvred hydraulically so as to engage with a closed hook fixed on the front of a skip and enable the front end of that skip to be raised over the tail end of the vehicle and the skip as a whole then to be dragged into its transporting position on the rear chassis of the vehicle.

[0006] For the transport of (empty) skips between sites, it is required that they be stackable, one within another, so that several such stacked skips can be carried at once by a single motor vehicle. In this case, with the second type of known skip discussed above, several skips are stacked and then the lowermost one is engaged by the open hook carried by the transport vehicle so as to drag the stack onto the rear of the vehicle. For enabling the stacking of one skip inside another with this type of skip, the skips are provided with a wheel or roller adjacent the rear ends of each of the two side walls, at about the mid-height of these walls, and with a respective fixed horizontal projection located at the same height as the wheels/rollers adjacent the front ends of the two side walls. By this means by hydraulic displacement of the open hook, a second skip mounted on the back of the transport vehicle, can be manoeuvred off the transport vehicle by the hook into a first skip on the ground, so that the wheels/rollers on the back of the upper skip are caused to run along the top edges of the side walls of the lower skip until the rear wall of the upper skip abuts the rear wall of the lower skip. The front end of the upper skip is then lowered by the hook on the vehicle to leave the fixed projections at the front ends of its side walls resting also on the top edges of the side walls of the lower skip.

[0007] Known skips of the latter type have several operational problems associated with them arising from the particular manner in which they are constructed.

[0008] Firstly, the structure of the known skips does not allow one skip to be received closely within another for stacking purposes, in that the underside of the base of the upper skip when placed in a lower skip remains separated by a significant distance from the upperside of the base of the lower skip as a result of the position of the rollers and fixed projections at the mid-height of the side walls of the skip and the fact that the supporting surfaces for these rollers and fixed projections are on the top edges of the side walls. This means that the resulting stack is taller than would be the case if one skip could be fitted more closely within another. One reason why the top edges of the side walls are chosen as the supporting surfaces for stacking purposes in the known skips is that the floor structure can be insufficiently strong to support the weight of the upper skip(s) and the floor of the underneath skips can be distorted in some situations.

[0009] Secondly, the location of the fixed closed hook on the front of the known skips for receiving the open hook carried by the transport vehicle is such that, when one or more skips are stacked on top of a lowermost skip, the open hook on the transport vehicle cannot easily be entered into the closed hook on the lowermost skip since it is obstructed by the overhang of the front walls of the or each of the stacked skips thereabove.

[0010] According to a first aspect of the present invention, in a skip of the second type fitted with a closed hook on its inclined front wall for engagement with an open hook on the transport vehicle, the closed hook is mounted displaceably on said inclined front wall, so that it can be selectively extended to a position forward of, and above the level of, the top edge of said front wall of the skip.

[0011] Preferably, the closed hook is longitudinally displaceable relative to a housing which is fixed rigidly relative to said front wall of the skip.

[0012] Advantageously, the closed hook is carried by, and connects together the one ends of, a pair of parallel bars, whose other ends are also rigidly connected together by a further member, the pair of parallel bars being slidably received in respective parallel guides fixed to said inclined front wall of the skip.

[0013] Preferably, the parallel bars, and also the guides in which they are received, are made of box-sectioned steel.

[0014] Through-holes can be provided in the parallel bars for receiving respective metal pins to hold the hook in its extended position.

[0015] According to a second aspect of the present invention, the skip base is formed by a pair of side girders, coupled together by cross beams and covered by a steel plate forming the skip floor, the side girders being arranged to extend substantially over the full length of said skip floor.

[0016] When then the rear end of the skip is provided with a transverse roller on its underside which extends across the width of the skip floor, the roller of an upper skip to be stacked on a similar lower skip can run along the length of the skip floor, supported by said side girders to prevent distortion of said skip floor.

[0017] According to a third aspect of the present invention, said side girders supporting the skip floor comprise respective lengths of channel iron, disposed so that their respective channels both face laterally outwardly at the sides of the skip base, and wherein the side walls of the skip comprise a plurality of side beams which extend upwardly at an angle to the base, the lower ends of these side beams being welded to the upper surface of the lower leg of the associated side girder and the sides of these side beams being welded to the outer edge of the upper leg of the associated side girder. This arrangement achieves a particularly strong and rigid structure for the side walls of the skip.

[0018] The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings in which:-

Fig. 1 is a diagrammatic plan view of one embodiment of a skip in accordance with the present invention;

Fig. 2 is a diagrammatic side view of the skip of Fig. 1, with an extensible closed hook on the front of the skip in its fully extended position;

Fig. 3 is a diagrammatic rear end view of the skip of Figs. 1 and 2 illustrating how one skip will stack closely within another skip;

Fig. 4 is a diagrammatic detail view illustrating several constructional aspects of the skip;

Fig. 5 is a detail view illustrating the extensible closed hook on the front of the skip in its fully retracted position;

Fig. 6 is a detail front view illustrating the extensible closed hook in its fully extended condition;

Fig. 7 is a side view of the extended hook of Fig. 6;

Fig. 8 is a plan view of the hook of Fig. 6; and

Fig. 9 shows in more detail certain location elements on the front of the skip.

[0019] Referring first to Figs. 1 and 2, the illustrated skip comprises generally a rectangular base structure 10, two outwardly inclined side walls 12a, 12b, a forwardly inclined front wall 14 and a substantially vertical rear wall 16.

[0020] The base structure 10 includes two parallel, steel side-girders 18a, 18b which are rigidly interconnected by a number of cross girders 20. The side-girders 18a, 18b are of channel shaped section (channel iron) with the open sides of the channel facing outwardly. The open sides of the regions of the channel shaped girders 18a, 18b shown cross-hatched in Fig. 2 are closed by welded steel plates 22a, 22b, 22c so that the girders 18a, 18b become box-sectioned in these regions to give extra strength. A flat steel base plate 19 is welded over the tops of the girders 18a, 18b to form the floor of the skip.

[0021] The side walls 12a, 12b are formed from steel side plates 24a, 24b supported by a plurality of generally upwardly extending box-section steel bearers 26a, 26b and horizontal, box-section steel upper side beams 28a, 28b. The manner by which the upwardly extending bearers 26a, 26b are connected to the base structure is best seen from Fig. 4. As shown in this figure, each side bearer 26 is welded firstly to the horizontal upper face 30 of the lower leg 32a of the channel sectional girder 18 and secondly to the edge of the upper horizontal leg 32b of this girder. Thus, these side bearers 26 are each welded to the girders 18 of the base structure in two different places thereby achieving a particularly strong joint therebetween.

[0022] The angle A of the side plates 24 relative to the base plate 19 is preferably about 30°.

[0023] As best seen in the upper part of Fig. 3, the rear wall 16 comprises parallel upper and lower beams 34, 36 interconnected by angled side beams 38a, 38b, a central beam 40 and a steel plate 42. The lower beam 36 is coupled by hinges 44 to the rearmost cross girder 20 of the base so that it can swing down to enable full rear access to the skip interior. Removable bolts 46 at the upper sides of the rear wall enable this wall to be selectively locked in its closed position or to be released to enable it to be pivoted to its open position.

[0024] The front wall 14 is formed by an upper cross beam 48 which is welded at its ends to the side beams 28a, 28b, respectively and is again made of box-section steel. Two further, mutually inclined box-section beams 50a, 50b couple the upper cross beam 48 to front regions of the upper side surfaces of the main side girders 18a, 18b. A flat steel plate 52 is welded over the beams 48, 50a and 50b to complete the inner surface of the skip.

[0025] Welded to the upper cross beam 48, between the beams 50a, 50b, is an extensible hook structure 54, which is shown in more detail, and to a larger scale, in Figs. 6, 7 and 8. The hook structure 54 comprises a housing part 56 formed from two, parallel box-section elements 56a, 56b welded to the cross beam 48 and also to the upper ends of the angled beams 50a, 50b. Slidably received in the box-section elements 56a, 56b are respective box-section tubes 58a, 58b which are rigidly interconnected at their lower ends by a rectangular plate 60 and are rigidly interconnected at their upper ends by a length of curved steel bar 62 of circular section which effectively forms a curved "hook". The rigid structure comprised by the tubes 58a, 58b, end plate 60 and curved hook 62 can adopt different positions relative to the housing part 56. Thus, in its retracted rest position, shown dotted in Fig. 6, this rigid structure drops downwardly under gravity until the curved hook 62 engages the upper mouths of the box section elements 56a, 56b and therefore lies substantially at the same height as the cross beam 48 of the skip. On the other hand, the rigid structure 58a, 58b, 60, 62 can be drawn upward manually to an extended position (shown in full lines in Fig. 6) in which the closed 62 lies well above and in front of the upper cross beam 48 of the skip, as shown in Fig. 2. The closed hook 62 can be maintained in this extended position by inserting metal pins 66a, 66b through respective holes in the tubes 58a, 58b which engage against the upper ends of the box-section elements 56a, 58b to prevent the rigid structure 58a, 58b, 60, 62 falling under gravity to its rest position. Mechanisms can be provided for preventing inadvertent release of the pins 66, for example by cam locks of the type shown in the expanded detail of Fig. 7.

[0026] Disposed across part of the front of the box-section elements 56a, 56b is a bracket 68 (see also Fig. 9) which acts as a front skip support to assist in preventing the skip from jamming into a lower similar skip when stacked thereon. The bracket 68 comprises a length of channel iron mounted to the front of the skip so that its channel faces downwardly for engaging over the top of the upper cross beam 48 of a lower skip, in the manner of a saddle. Further brackets 69 are disposed outboard of the bracket 68 for limiting sideways displacement of the bracket 68 on an upper skip in the stacked condition. Thus, the co-operation of the brackets 68, 69 on the stacked skips assist in holding the stacked skip in the correct position on the skip below and reduces relative movement between these stacked skips.

[0027] As best seen in Figs. 2 and 3, the underside of the rear end of the skip is provided with a transversely extending roller 70 whose length is the same as or slightly less than, the width of the floor plate 19 of the skip. By virtue of this construction, a second, identical skip held by the open hook on the transport vehicle can be introduced, for stacking purposes, into a first skip by raising the front end of the second skip on the transport vehicle by means of the open hook, and displacing this skip off the rear end of the vehicle so that it tips up about the roller 72, with its rear end moving downwardly to engage its roller 70 with the floor panel 19 of the first skip on the ground. By continuing to displace the upper skip rearwardly, its roller 70 runs along the floor of the lower skip until the rear wall of the upper skip abuts that of the lower. The front end of the upper skip is then lowered further by the open hook so that the bracket 54 of the upper skip engages with the front cross beam 48 of the lower skip. Obviously, for this manoeuvre to operate correctly, the transport vehicle must align itself reasonably accurately with the first skip before the manoeuvre begins.

[0028] For removing (unstacking) a second skip stacked with a first, the operation is reversed.

[0029] It will be appreciated that during the abovedescribed movements, the roller 70 of the upper skip effectively runs along and is supported by the continuous girders 18c, 18b which extend along the full length of the base of the lower skip. In view of the inherent strength and rigidity of these girders, any tendency for buckling of the floor of the skip which might otherwise arise from the weight of the upper skip and its movement along the lower skip, is resisted and prevented. The roller 70 is dropped slightly from the skip base, as there is enough clearance, for the best stacking position.

[0030] The advantage of the closed hook being extensible to the position shown in Figs. 2 and 6 (full lines) is that when it is required for the open hook on the vehicle to be manoeuvred to engage with the closed hook on the lowermost skip of a stack of such skips, the closed hook of that lowermost skip can be displaced to its fully extended position in which it will lie forward and clear of the front end of the next (or other) skip in the stack which, as explained initially, would otherwise at least partially cover the hook of the lowermost skip and make access to it by the open hook on the vehicle very difficult.

[0031] Finally, returning to Fig. 4, this figure shows how the side girders 18a, 18b of the presently illustrated skip fit between the rollers 72 typically used on the lorry having the open L-shaped pick-up hook mentioned hereinbefore. As shown in Fig. 2, a lock pin 74 is provided on the base for locking a skip to another therebeneath in the stacked condition.

Claims

1. A stackable skip of the type comprising a four-walled, open-topped metal container whose front wall (14) is forwardly inclined, the container being adapted to be selectively mounted on a motor vehicle for the transport of materials carried by the skip by being dragged onto the rear of the transport vehicle by means of a hydraulically displaceable open hook carried by the vehicle, characterised in that the skip is fitted with a closed hook (62) on its inclined front wall for engagement with the open hook on the transport vehicle, the closed hook being mounted displaceably on said inclined front wall (14), so that it can be selectively extended to a position forward of, and above the level of, the top edge of said front wall (14) of the skip.

2. A stackable skip as claimed in claim 1, wherein the closed hook (62) is longitudinally displaceable relative to a housing (56) which is fixed rigidly relative to said front wall (14) of the skip.

3. A stackable skip as claimed in claim 2, wherein the closed hook (62) is carried by, and connects together the one ends of, a pair of parallel bars (58a, 58b), whose other ends are also rigidly connected together by a further member (60), the pair of parallel bars being slidably received in respective parallel guides (56a, 56b) fixed to said inclined front wall (14) of the skip.

4. A stackable skip as claimed in claim 3, wherein the parallel bars (58a, 58b), and also the guides (56a, 56b) in which they are received, are made of box-sectioned steel.

5. A stackable skip as claimed in claim 3 or 4, wherein the parallel bars (58a, 58b) include through-holes for receiving respective metal pins (66a, 66b) to hold the hook (62) in its extended position.

6. A stackable skip as claimed in any of claims 1 to 5, wherein the container includes a base which is formed by a pair of side girders (18a, 18b), coupled together by cross beams (20) and covered by a steel plate (19) forming the skip floor, the side girders (18a, 18b) being arranged to extend substantially over the full length of said skip floor.

7. A stackable skip as claimed in claim 6, wherein a rear end of the skip is provided with a transverse roller (70) on its underside which extends across the width of the skip floor, wherein the roller (70) of an upper skip to be stacked on a similar lower skip can run along the length of the skip floor (19), supported by said side girders (18a, 18b) to prevent distortion of said skip floor.

8. A stackable skip as claimed in claim 6 or 7, wherein said side girders (18a, 18b) supporting the skip floor comprise respective lengths of channel iron, disposed so that their respective channels both face laterally outwardly at the sides of the skip base, and wherein the side walls of the skip comprise a plurality of side beams (26) which extend upwardly at an angle to the base, the lower ends of these side beams (26) being welded to the upper surface of the lower leg of the associated side girder (18a, 18b) and the sides of these side beams being welded to the outer edge of the upper leg of the associated side girder (18a, 18b).

9. A stackable skip of the type comprising a four-walled, open-topped metal container whose front wall (14) is forwardly inclined, the container being adapted to be selectively mounted on a motor vehicle for the transport of materials carried by the skip by being dragged onto the rear of the transport vehicle by means of a hydraulically displaceable open hook carried by the vehicle, characterised in that the skip is itself fitted with a hook (62) on its inclined front wall for engagement with the open hook on the transport vehicle, the hook (62) being mounted displaceably on said inclined front wall (14), so that it can be selectively extended to a position forward of, and above the level of, the top edge of said front wall (14) of the skip.

10. A stackable skip as claimed in claim 1, wherein the hook (62) is longitudinally displaceable relative to a housing (56) which is fixed rigidly relative to said front wall (14) of the skip.

Drawing