GB2137161A - Tines for pallet trucks - Google Patents

Abstract

Each tine 30 of a pallet truck has a load wheel 32 and, disposed forwardly thereof, a tine entry guide arrangement 34 comprising one or more arcuate carrier plates 36 pivoted at 46 and on which are freely rotatable leading and following rollers 42, 44. The plates 36 are pivoted so that the roller 44 will normally assume a disposition lower than the other roller 42. When the roller 44 encounters a bottom board 22 of a pallet 10 it causes the leading roller 42 to descend and press down on the board 22 thereby raising tine 30 to assist the load wheel 32 in its passage over the bottom board, and inhibiting movement of the pallet 12. <IMAGE>

Description

SPECIFICATION Pallet trucks This invention concerns pallet trucks.

In practical use of tined pallet trucks, particularly but not exclusively so-called low-lift pallet movers in which the tines are each furnished with a load wheel or roller, problems can arise in relation to picking up empty or lightlyloaded so-called "bottom perimeter boarded pallets".

Pallets normally comprise an array of parallel top slats carried upon cross members which, in turn, are provided at the tops of upright spacers which are spaced apart to provide, beneath the slats, entries for the tines of a pallet truck. These entries may extend longitudinally of the pallet or transversely thereof. In bottom perimeter boarded pallets, bottom boards are provided beneath the upright spacers, these bottom boards usually extending longitudinally of the pallet, Accordingly, with this kind of pallet, engagement of the tines of the pallet truck into the entries does not just involve insertion of the tines below the top slats and cross members, but involves inserting the tines over the bottom boards.

In the case of pallet trucks of the kind wherein the tines have no load wheels or rollers, unimpeded introduction of the tines into the entries can be achieved provided they are adjusted precisely to the correct height, and the truck approaches the pallet with the tines accurately registered with the entries. With lightly-loaded or empty pallets, any slight imprecision in the height of the tines and/or registration of the tines with the entries can result in physical contact between the tine(s) and the pallet, with the result that the latter may be pushed about and proper tine engagement is not achieved.

The possibility of the empty pallet or lightlyloaded pallet being pushed about by the tines is very much greater in the case of pallet trucks having load wheels near to their outer ends. There is no possibility of avoiding physical engagement of the load wheels with the bottom boards, even when the tines are most accurately aligned with the entries, and accordingly the handling of bottom perimeter boarded pallets with this kind of pallet truck can be particularly difficult.

An object of the present invention is to provide a pallet truck which is so constructed that the above-discussed difficulty is obviated or minimised, the arrangement providing for forces to be applied to the pallet to tend to hold the pallet stationary during tine insertion.

With this object in view, the present invention provides a pallet truck comprising a pair of raisable tines for introduction into entries in a pallet, characterised by the provision, at or adjacent the leading end of each tine, of a tine entry guide arrangement comprising successively a leading bottom-board-engaging component and a following botton-board-engaging component, these components being arranged so as normally to assume a disposition with the following component lower than the leading component and being interconnected so that raising of the following component causes lowering of the leading component.

With this arrangement, when the tines are introduced into the entries of a bottom perimeter boarded pallet, even light engagement of the following bottom-board-engaging component with the bottom board results in raising of such component, thereby causing lowering of the leading component so that the latter presses down upon the bottom board of the pallet. This has the effect, of course, of ensuring that the pallet is pressed firmly down upon the ground and accordingly will not move around.

The leading and following components may, if desired, be formed as part of a unitary structure.

Thus, they may, for instance, be provided by respective portions, of a pivoted shoe, disposed respectively forwardly of and rearwardly of the pivot of such shoe, the disposition of the pivot and/or the weight distribution of the shoe relative to the pivot being such as to bias the shoe to its position with the following component lower than the leading component.

Preferably, however, the said components are rollers carried by a pivoted yoke or the like of which the pivot is disposed so that the following roller is biassed towards a lower disposition than the leading roller, under the influence of gravity.

In the case where each tine of the pallet truck has a respective load wheel or roller, each tine guide arrangement will, of course, be disposed, on its tine, forwardly of the respective load wheel or roller. The guide arrangement is, then, preferably such as to tend to raise the tine to contribute to the load wheel or roller moving over the bottom perimeter boards.

Advantageously each tine of the pallet truck has two respective load wheels or rollers carried by a pivoted yoke or the like of which the pivot is disposed substantially centrally of said yoke and rearwardly of the respective tine entry guide arrangement. The guide arrangement is then such that it will tend to raise the tine thereby contributing to the load wheels or rollers moving over the bottom boards.

In a preferred embodiment of the invention, each tine also has a tine withdrawal guide arrangement which is similar to, but reversed relative to, the tine entry guide arrangement, to facilitate passage of the load wheel over the bottom perimeter boards upon tine withdrawal.

The truck of the invention may further include, between the load wheel or roller and the time withdrawal guide arrangement, a supplementary guide roller disposed with its lower running surface at a level slightly higher than that of the load wheel or roller.

The invention will be described further, by way of example, with reference to the accompanying drawing in which: Fig. 1 is a perspective view illustrating a bottom perimeter boarded pallet; Fig. 2 is a diagrammatic side elevation illustrating the forward end of one tine of a pallet truck constructed in accordance with the invention so as to be particularly suitable for handling bottom perimeter boarded pallets such as that shown in Fig. 1, the tine just entering the pallet; Fig. 3 is a view similar to Fig. 2, but showing the leading end of the tine having penetrated the pallet; Fig. 4 is a view similar to Figs. 2 and 3, but showing the tine further entered into the pallet; and Fig. 5 is a view similar to Fig. 2 illustrating a second embodiment of the pallet truck having two loads wheels on each tine.

Referring firstly to Fig. 1, this figure iliustrates a typical bottom perimeter boarded pallet, which is indicated generally by the reference numeral 1 0.

The pallet comprises an array of top slats 12, which number five in the example but may be fewer or more dependent upon practical circumstances. These top slats 12 are spaced apart by being secured to cross members 14, of which there are three, these being boards which are generally similar to the slats 12. The assembly consisting of the array of slats 1 2 and the cross members 14 is supported so as to be at a predetermined height above the ground or other supporting surface, by upright spacers 1 6 of which there are nine, these spacers 1 6 being in the form of wooden blocks disposed one at each corner, one midway between each corner, and one in the middle of the pallet.

The spacers 1 6 serve, of course, to define longitudinal tine entries as indicated by the arrows 18, and transverse tine entries as indicated by the arrows 20.

As so far described, the pallet corresponds to a normal or standard pallet. The illustrated construction differs from the normal or standard pallet, however, in that it has bottom perimeter boards 22 and 24 and an intermediate bottom board 26, these all extending longitudinally of the pallet and being secured to the corresponding spacers 1 6 so as to impart additional stability thereto and additional overall strength to the entire pallet.

Turning now to Fig. 2, this figure shows the forward end of one tine 30 of a pallet truck, which may be of the kind sometimes known as a low level pallet mover, which comprises a powered mobile body (not shown) from which project two parallel and substantially identical tines 30, these being carried by a cross head (not shown) which can be raised and lowered through a small height, e.g. from 10 to 20 cms.

Each tine 30 is of inverted-channel construction, and has a load wheel arrangement which is illustrated diagrammatically as a wheel or roller at 32 and which sinks and rises relative to the tine 30 upon raising and lowering of the latter so as to provide for the forward end of the tine 30 always to be supported from the ground. The form of this load wheel arrangement can, of course, differ from what has been illustrated by way of example. As so far described, such tine constructions are well known.

Forwardly disposed relative to the load wheel or roller 32 is a tine entry guide arrangement which is indicated generally by the reference numeral 34. This arrangement 34 comprises an arcuate yoke or shoe composed of two side-byside arcuate carrier plates 36 between which extend substantially parallel spindles 38, 40 on which are freely rotatable respective rollers 42, 44. The roller 42 is a leading component of the entry guide arrangement 34 and the roller 44 is a following component thereof. The yoke or shoe composed of the plates 36 is carried by a pivot 46 extending between the side walls of the tine 30, this pivot 46 being disposed slightly forwardly of the centre of gravity of the yoke or shoe, so that the following component or roller 44 will normally assume a disposition, as shown, wherein it is lower than the leading component or roller 42.

Journalled in an inverted-U shaped bracket 48 disposed rearwardly of the load wheel or roller 32 is a supplementary guide roller 50 the lower surface of which is at a level, above the floor, approximately equal to the thicknesses of the bottom perimeter boards 22 and 24. This supplementary guide roller 50 is disposed between the load wheel or roller 32 and a withdrawal guide arrangement indicated generally by the reference numeral 60. This withdrawal guide arrangement 60 is similar to the entry guide arrangement 34 but is in a relatively reversed disposition.

More particularly, the withdrawal guide arrangement 60 comprises only a simple arcuate side plate 62 pivotally mounted on one of the side walls of the tine 30 by a pivot 64 and carrying respectively a leading component in the form of rotatable roller 66 and a following component in the form of roller 68. This withdrawal guide arrangement 60 is mounted to one side of the centre line of the tine 30 to permit the presence of components extending up to the load wheel or roller 32.

Referring to Fig. 5, this figure illustrates a second embodiment of the pallet truck of the invention. In this embodiment parts which are similar to those present in the first embodiment are referred to by the same reference numerals. A tine 30 has a tine entry guide 34 comprising an arcuate yoke 36, parallel spindles 38, 40 on which are freely rotatable rollers 42, 44 and a pivot 46 upon which the entry guide 34 is carried. In place of the single load wheel 32 present in the first embodiment the load wheel arrangement 70 comprises two wheels or rollers 72, 74 carried, in a similar manner to the tine entry and withdrawal guides, by a yoke 82 having two freely rotatable spindles 78, 80 onto which the respective wheels or rollers 72, 74 are attached. The yoke 82 is carried by a pivot 76 extending between the side walls of the tine 30. Disposed rearwardly of the load wheel arrangement 70 is a supplementary guide roller 50 carried in an inverted U shaped bracket 48. Also disposed rearwardly of the supplementary guide roller 50 is a tine withdrawal guide 60. This configuration of the load wheel arrangement ensures that the tine elevation is maintained and entry into the pallet is ensured.

The mode of operation of the illustrated construction will be evident from Figs. 3 and 4.

When it is desired to lift the pallet 10 using the pallet mover having two of the tines 30, the tines 30 are, of course, brought into register with the entries 20 and the pallet mover is advanced to cause the tines 30 to move into the entries 20.

The leading rollers 42 are at a height such as to pass over the perimeter board 22, but this board 22 is encountered by the following rollers 44. As a result the rollers 44 tend to rise, thereby pivoting the leading rollers 42 to descend and press down on the perimeter board 22 as shown in Fig. 3.

Accordingly, the action of the entry guide arrangements 34 is such as (a) to apply pressure onto the perimeter board 22 thereby to cause the pallet 10 to be held stationary and (b) to tend to apply a lifting force to the leading end of the tine 30 thereby to assist the load wheel or roller 32 in its passage over the perimeter board 22.

As shown in Fig. 4 the load wheel or roller 32 runs off the perimeter board 22 and is followed by the supplementary guide roller 50 which then rests on the perimeter board 22 and helps passage thereover of the withdrawal guide arrangement 60 of which the leading roller 66 is at a lower level than the following roller 68.

The operation of the guide arrangements 34 and 60 is the same for the intermediate base board 26, but in relation to the further perimeter board 24, usually only the entry guide arrangement 34 will be involved and such board 24 will not be encountered by the withdrawal guide arrangement 60. The construction of the tines 30, is, thus, such that the tines 30 will enter into the entries 20 of the pallet 10 with the minimum of risk of the pallet 10 moving about, woven in the case where it is empty or only lightly loaded.

Similarly, there is no difficulty in tine withdrawal, the withdrawal guide arrangements 60 contributing to this.

It can be seen that such a tine entry guide arrangement will allow the pallet truck to be used with a large range of perimeter board thicknesses without any mechanical adjustment.

The invention is not confined to the precise details of the foregoing example and variations may be made thereto. Thus, for instance, it is not essential for the guide arrangements to have rollers, such as the rollers 42, 44, 66 and 68, and each such arrangement may include, for instance, an arcuate or other-shaped shoe or skid which operates in a manner similar to the described roller arrangements. Other variations may also be possible.

Claims (8)

1. A pallet truck comprising a pair of raisable tines for introduction into entries in a pallet, characterised by the provision, at or adjacent the leading end of each tine, of a tine entry guide arrangement comprising successively a leading bottom-board-engaging component and a following bottom-board-engaging component, these components being arranged so as normally to assume a disposition with the following component lower than the leading component and being interconnected so that raising of the following component causes lowering of the leading component.

2. A pallet truck as claimed in claim 1 wherein the leading and following components are provided by respective portions of a pivoted shoe, disposed respectively forwardly of and rearwardly of the pivot of such shoe, the disposition of the pivot and/or the weight distribution of the shoe relative to the pivot being such as to bias the shoe to its position with the following component lower than the leading component.

3. A pallet truck as claimed in claim 1 wherein the said components are rollers carried by a pivoted yoke or the like of which the pivot is disposed so that the following roller is biassed towards a lower disposition than the leading roller, under the influence of gravity.

4. A pallet truck as claimed in claim 1, 2 or 3 wherein each tine of the pallet truck is provided with a respective load wheel or roller disposed rearwardly of the respective tine entry guide arrangement such that the tine guide arrangement will tend to raise the tine thereby contributing to the load wheel or roller moving over the bottom boards.

5. A pallet truck as claimed in claim 1, 2 or 3 wherein each tine of the pallet truck is provided with two respective load wheels or rollers carried by a pivoted yoke or the like of which the pivot is disposed substantially centrally of said yoke and rearwardly of the respective tine entry guide arrangement such that the tine guide arrangement will tend to raise the tine thereby contributing to the load wheels or rollers moving over the bottom boards.

6. A pallet truck as claimed in claim 4 wherein each tine also has a tine withdrawal guide arrangement which is similar to, but reversed relative to, the tine entry guide arrangement, to facilitate passage of the load wheel over the bottom perimeter boards upon tine withdrawal.

7. A pallet truck as claimed in claim 4 or 5 wherein the truck is provided, between the load wheel or roller and the tine withdrawal guide arrangement, with a supplementary guide roller disposed with its lower running surface at a level slightly higher than that of the load wheel or roller.

8. A pallet truck substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.