GB2366282A

GB2366282A - Improvements in and relating to fork lift trucks

Info

Publication number: GB2366282A
Application number: GB0115285A
Authority: GB
Inventors: Roy Warren Waterfield
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-06-22
Filing date: 2001-06-22
Publication date: 2002-03-06
Anticipated expiration: 2021-06-22
Also published as: GB2366282B; GB0015158D0; GB0115285D0

Abstract

For extending the working life of the forks of a fork lift truck there is provided an adaptor means comprising a base member 11, an upper member 25, interconnection means 31 extending between the base and upper members, and adjustable retention means 31,32 whereby at least said base member may be secured to the under side of a fork 30 at the heel region thereof. The base member 11 may be of an elongate shape having thickened end regions for engaging a ground surface and an intermediate region which normally lies clear of the ground surface in an alternative (figure 5, not shown) a separate wear shoe is provided for each tine of the fork.

Description

<Desc/Clms Page number 1> Improvements in and Relating to Fork Lift Trucks This invention relates to a method of and apparatus for extending the safe working life of the forks of a fork lift truck.

Safety, and sometimes also operational considerations, dictate that during movement of a fork lift truck, whether in a loaded or an unloaded condition, the forks are maintained in a down position at no more than a prescribed height above ground. One consequence is that often the truck driver will not trouble to slightly elevate the forks when moving from one work area to another. Instead he will simply leave the forks in a fully down position, with the forks then rubbing over and being worn by the ground surface.

The aforementioned wear commonly occurs primarily in the so-called heel region of each fork, being the region at the end of the fork nearest to the rack mechanism and at which the fork has an L shape between a load-carrying, substantially horizontally extending portion, and a vertically extending portion connected to the rack mechanism. Any such wear of a fork at the heel region is particularly undesirable because it is that region of the fork which generally is subject to the maximum bending moment when carrying a load. If wear is not kept under periodic review there is a significant risk that a fork might unexpectedly break or deflect in service, with potentially dangerous consequences.

Consideration has been given to manufacturing the forks from a more wear- resistant material, or to providing an interlock which inhibits more than a prescribed extent of truck movement when the forks are in a fully down position. Such potential solutions, however, are not practical because of cost considerations and/or restriction on operating freedom and speed.

One object of the present invention is to provide an improved method of and apparatus for extending the potential working life of the forks of a fork lift truck. In accordance with one aspect of the present invention there is provided a method of extending the working life of the forks of a fork lift truck, said method comprising the steps of providing a base member of wear-resistant material, said base member having a location portion for attachment to the underside of the heel region of a fork, providing an upper member to sit over the fork in the vicinity of the heel region, and providing interconnection means to interconnect between said base and upper members whereby the base member may be secured to the underside of the fork heel region.

The method may comprise use of interconnection means which is integral with at least one of the base member and said upper member.

The method preferably comprises provision of base and upper members at the heel regions of each of the two forks with which a fork lift truck conventionally is provided.

The method preferably comprises use of adjustable interconnection means, for example a nut and bolt assembly, which extends alongside an edge of a fork, thereby obviating any need to drill or otherwise form an opening in a fork for allowing interconnection means to extend therethrough.

Use may be made of interconnection means which is adjustable to cause the base and upper members to be clamped to a fork, or the interconnection means may be non-adjustable and separate, adjustable retention means may be provided, for example to act between the upper member and an upper surface of a fork, to clamp the base member against the underside of the fork.

In accordance with a second aspect of the present invention there is provided adaptor means for extending the working life of the forks of a fork lift truck, said means comprising a base member, an upper member, interconnection means extending between the base and upper members, and adjustable retention means whereby at least said base member may be secured to the under side of a fork at the heel region thereof.

Preferably at least one of the base and upper members is of an elongate form whereby it may extend transversely between the forks. It is further preferred that both of the base and upper members extend transversely between the forks, the references herein to the word 'transversely' being used to refer to a direction which extends substantially perpendicular to the length direction of the forks from their respective heel regions to their distal ends.

The invention further provides a fork assembly and a fork lift truck comprising a fork assembly having a pair of forks provided with the adaptor means of the present invention. Preferably the interconnection means is positioned alongside outside edges of the forks, though positioning of the interconnection means between the forks is not excluded.

Preferably at least two interconnection means are provided and positioned each in close proximity to a respective fork of a pair.

The invention further teaches that preferably the base member is adapted to extend transversely between a pair of forks and is provided with thickened end

regions which, in use, lie respectively beneath the underside regions of the forks. It is further preferred that the base member is provided with a non-planar surface which, in use, is arranged to face downwards such that thickened end regions come into contact with a ground surface and an intermediate region between said end regions remains above the ground surface. In consequence the risk of a transverse base member abutting a ground object or surface irregularity is not substantially greater than the risk prevalent in respects of a pair of forks bereft of the adaptor of the present invention.

Suitable materials for the base member, and optionally also the upper member, include steel, aluminium, and reinforced composite materials.

Preferably at least one of the base and upper members is provided with a non- planar abutment surface adapted to conform substantially with a curved profile of a fork at a heel region between the substantially vertically and the horizontally extending portions thereof. Thus, for example, a base member may comprise a concave surface zone to abut the curved, convex, profile of the underside of a fork at the heel region. Similarly, an upper member of the adaptor preferably is provided with a convex surface zone to nest closely into the concave surface conventionally present at the heel region.

The base and upper members may each extend transversely between the forks of a pair and may be adapted to be maintained spaced from one another by the forks when in a fully assembled condition in which the base and upper members are clamped to the forks by the interconnection means or other retention means. The base member may comprise a recess aligned with an aperture and adapted to locate a bolt head, nut or other part of an interconnection means.

The adaptor may comprise a base or upper member having a shoulder region locatable against an edge of a fork, thereby for example to assist in providing transverse location of the adaptor relative to the forks.

The adaptor means may comprise a wear sensor or indicator to provide an indication of degree of wear of the adaptor. The sensor may be of a kind that provides a visual indication, or it may, for example, be of a kind which provides an audible warning.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings wherein :-

Figures 1 a, b and c are side, plan and end views respectively of part of a base member of an adaptor of a first embodiment of the invention; Figures 2a,b and c are side, plan and end views respectively of part of an upper member for use with the base member of figure 1; Figure 3 is an assembly view showing the members of figures 1 and 2 secured to a truck fork; Figure 4a, b,and c are side, plan and end views respectively of a part of another upper member for use with the base member of figure1, and Figure 5 is a perspective view of an adaptor in accordance with a second embodiment of the invention.

An adaptor 10 of a first embodiment of the invention comprises a base member 11 having a central section 12 for extending transversely between a pair of forks of a fork lift truck. At each end 13 ( one only shown in figure 1) the base member has a thickened wear region 14 to provide a wear surface 15 which, in use, lies below the lower face 16 of the central section 12, this being closer to the ground surface when in use.

The upper surface 17 of the section 12 is of a concave cross-section. Each end 13 has a shoulder zone 18 which defines an abutment edge 19 that in use lies alongside a fork. The pair of abutment edges assist in transversely locating the adaptor relative to a pair of forks. Each end region 13 additionally has a drilled aperture 20 for a retention bolt, the lower end of the aperture being enlarged and being of hexagonal shape 21 to accommodate, and restrain rotation of, a bolt head.

The adaptor additionally comprises an upper member 25 having a length corresponding to that of a base member. It is of substantially uniform cross- sectional shape, and has a lower surface 26 of a convex shape to nest into the heel region of a fork. Each end 27 is provided with a through-bore alignable with aperture 20 of the base member so that a retention bolt can extend therethrough.

As shown in figure 3, in use of the adaptor 10 with the forks 30 ( one only shown ) of a fork lift truck, the base and upper members 11, 25 are held clamped against under and upper surfaces of the fork heel regions by means of retention bolts 31 and securing nuts 32.

In a modification of the aforedescribed embodiment the upper member ( see figure 4 ) may have a shoulder zone 33 at each end, each shoulder zone defining an abutment edge 34 that assists in transversely locating the upper member in a manner similar to location provided by the edges 19 of the base member 11. The height of the abutment edge 34 when added to that of the abutment edge 19 is selected to be slightly less than the thickness of the forks whereby the retention bolts similarly are able to provide a clamping action.

In the aforedescribed embodiments the retention bolts 31 and nuts 32 act (a) as adjustable retention means to clamp the adaptor to the forks and (b) as interconnection means which interconnects the base and upper members. In the embodiment of figure 5 a shoe type adaptor 40 for attachment to an individual fork comprises a base portion 41 and upper portion 42 substantially similar to the aforedescribed base and upper members, but permanently and non-adjustably interconnected by an interconnection portion 43.

The base portion 41 has a shoulder 44 spaced from the intermediate portion 43 by a distance corresponding to the fork width.

The upper portion 42 is provided with a screw-threaded aperture 45 which receives a retention bolt which can be rotated to cause the end of the bolt to bear firmly against an upper surface of a fork and thereby hold the base portion firmly against the underside of a fork heel region.

Claims

CLAIMS: 1. An adaptor means for extending the working life of the forks of a fork lift truck, said adaptor means comprising a base member, an upper member, interconnection means extending between the base and upper members, and adjustable retention means whereby at least said base member may be secured to the under side of a fork at the heel region thereof.
2. An adaptor means according to claim 1, wherein at least one of the base and upper members is of an elongate form whereby it may extend transversely between the forks.
3. An adaptor means according to claim 3, wherein both of the base and upper members are of an elongate form whereby they may extend transversely, as hereinbefore defined, between the forks.
4. An adaptor means according to claim 2 or claim 3, wherein at least two interconnection means are provided and positioned each to lie, in use, in close proximity to a respective one of the forks of a pair.
5. An adaptor means according to any one of claims 2 to 4, wherein the base member is adapted to extend transversely between a pair of forks and is provided with thickened end regions which, in use, lie respectively beneath the underside regions of the forks.
6. An adaptor means according to any one of the preceding claims, wherein the base member is provided with a non-planar surface which, in use, is arranged to face downwards.
7. An adaptor means according to claim 5 or claim 6 when dependent on claim 5, wherein said that thickened end regions are adapted to come into contact with a ground surface and an intermediate region between said end regions remains above the ground surface.

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8. An adaptor means according to any one of the preceding claims, wherein at least one of the base and upper members is provided with a non-planar abutment surface adapted to conform substantially with a curved profile of a fork at a heel region between the substantially vertically and the horizontally extending portions thereof.
9. An adaptor means according to any one of the preceding claims, wherein the base and upper members are adapted, in use, to extend transversely between the forks of a pair and to be maintained spaced from one another by the forks when in a fully assembled condition in which the base and upper members are clamped to the forks by the interconnection means or other retention means.
10. An adaptor means according to anyone of the preceding claims, wherein the base member comprises a recess aligned with an aperture and is adapted to locate a bolt head, nut or other part of an interconnection means.
11. An adaptor means according to any one of the preceding claims, wherein at least one of the base and upper members comprises a shoulder region locatable against an edge of a fork for providing transverse location of the adaptor relative to the forks.
12. An adaptor means according to any one of the preceding claims, wherein the adaptor means comprises a wear sensor or indicator to provide an indication of degree of wear of the adaptor means.
13. An adaptor means according to claim 12, wherein the sensor provides a visual indication of the degree of wear.
14. An adaptor means according to claim 12, wherein the sensor provides an audible warning related to the degree of wear.
15. An adaptor means according to any one of the preceding claims, wherein the interconnection means substantially rigidly interconnects the base and upper members.

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16. An adaptor means according to any one of claims 1 to 14, wherein the interconnection means acts as said adjustable retention means.
17. An adaptor means according to claim 1 and substantially as hereinbefore described.
18. A fork assembly for a fork lift truck and comprising a pair of forks provided with an adaptor means according to any one of the preceding claims.
19. A fork assembly according to claim 18, wherein the interconnection means is positioned alongside the outside edges of the forks.
20. A fork lift truck comprising a fork assembly according to claim 18 or claim 19.
21. A method of extending the working life of the forks of a fork lift truck, said method comprising the steps of providing a base member of wear-resistant material, said base member having a location portion for attachment to the underside of the heel region of a fork, providing an upper member to sit over the fork in the vicinity of the heel region, and providing interconnection means to interconnect between said base and upper members whereby the base member may be secured to the underside of the fork heel region.
22. Method according to claim 21, and comprising use of interconnection means which is integral with at least one of the base member and said upper member.
23. Method according to claim 21 or claim 22 and comprising provision of base and upper members at the heel regions of each of the two forks of a fork lift truck.
24. Method according to any one of claims 21 to 23 and comprising use of adjustable interconnection means.

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25. Method according to anyone of claims 21 to 24 and comprising use of interconnection means which is adjustable to cause the base and upper members to be clamped to a fork.
26. Method according to any one of claims 21 to 24 and comprising use of nonadjustable interconnection means and separate, adjustable, retention means to clamp the base member against the underside of a fork.
27. Method according to claim 21 and substantially as hereinbefore described.