GB2279325A

GB2279325A - Load fork heel guard

Info

Publication number: GB2279325A
Application number: GB9411144A
Authority: GB
Inventors: Nigel Colin Haddock
Original assignee: JONES TREFOR
Current assignee: JONES TREFOR
Priority date: 1993-06-03
Filing date: 1994-06-03
Publication date: 1995-01-04
Also published as: GB9411144D0; WO1994029213A1; AU6804694A

Abstract

A heel guard 10 for a fork lift truck load fork. Load forks generally wear at the base of the heel portion and the present heel guard, which may be in the form of a plate which is removably attachable to the base of the heel region of the load fork, prevents such wear. Preferably the guard is rectangular and removably held by a clip 20. The guard can be of hard plate with "Stellite" (RTM) sections or of sacrificial material. The guard can be attached by a ring which can be adjustable (Fig 6) and have a shock absorbing portion (Fig 5). <IMAGE>

Description

Load Fork Protector This invention relates to fork lift trucks and all lifting appliances which utilise load fork attachments - (telescopic handlers, excavators, crane handlers etc), and in particular for the protection of the load forks thereof.

Fork lift trucks in particular are widely used by industry throughout the world, and fork lift truck owners make considerable expenditure in the replacement of load forks.

The load forks are a component which require regular inspection, as they are highly prone to failure. The main problem which inspectors look for on fork lift trucks are the elongation of load chains and the wear of the heel area of the load forks fitted.

The problems occurring in the heel areas of load forks generally arise by incorrect operation of the fork lift trucks. If a fork lift truck is mishandled so that the load forks contact the ground during motion of the fork lift truck, the heel areas of the load forks wear away. This in fact occurs in the majority of cases. In most countries legal standards apply as to the amount of wear allowed on a load fork before it requires replacement, and in Britain the legal limit is a 10% loss in thickness at the heel area.

New forks can cost between 200 and 900 per pair, and often the forks need replacement at the six-monthly inspection interval.

The present invention is concerned with a means for the alleviation of wear at the load fork heels, and hence the saving of the cost of regular replacement of the load forks, due to wear.

According to the present invention there is provided a guard for a load fork, comprising a load fork wear protector and fixing means whereby the said protector can be attached below the heel area of the load fork. The wear protector is preferably replaceable and is suitably in the form of a sacrificial wear means.

The said fixing means is preferably adapted to embrace the load fork, and may comprise a threaded member for adjusting the embrace of the fixing means.

The fixing means may comprise a securing ring which embraces both the load fork and the protector, and the securing ring preferably consists of two portions threadingly connected by one or more elongate nuts such that the embrace of the securing ring may be adjusted by turning the said one or more elongate nuts.

The fixing means preferably comprises abutment means adapted to act against the rear of the fork shank, and which preferably comprise one or more securing load screws which are threadingly mounted so that fitting adjustment can be effected by adjustment thereof.

The guard may comprise a sheath of rectangular cross section, which may slip over the end of a load fork and is affixed to the heel area thereof. The sheath preferably comprises side walls which protrude from the rear of the load fork when positioned and which comprise recesses or apertures wherein a fixing means is engageable to fix the sheath in place over the load fork heel.

The sheath may also comprise a vertical slot in one side thereof to allow for heel wear measurement, by an inspector, without the need for removal of the heel guard.

The wear protector is preferably removably secured to a carriage means so that replacement of the protector can occur without the need for replacement of substantially the entire device.

The said carriage means may be adapted to accommodate bolts whereby the said protector can be affixed thereto.

The guard may further comprise shock absorption means such as intermediate cushions made from Neoprene and adhesive shock pads as produced by the company 3M.

The protector is preferably in the form of a hard-wearing plate.

The hard-wearing plate may be made from hardened or tempered high carbon steel, which may pt creased in durability by the provision of "steliteli weld sections transversely disposed along its underside, or alternatively the hardwearing plate may be manufactured from mild steel having the same stelite welds on its underside to improve durability.

The said hard-wearing plate may have a diagonally upturned portions projecting forwardly, to deflect objects coming into contact with the front portion of the wear prevention means.

The present invention will now be described by way of example only, with reference to the accompanying figures, wherein: Fig. 1 shows in oblique view a heel guard according to the present invention; Fig. 2 shows in side view the heel.

Fig. 3 shows a detailed view the heel guard arrangement of Fig. 2; Fig. 4 shows an oblique view of a further embodiment of the invention; Fig. 5 shows a partially cross sectional view of a further embodiment of the present invention affixed to the heel area of a load fork; Fig. 6 illustrates in plan view an adjustable securing ring for use in the invention; Fig. 7 shows in oblique view a yet further embodiment of the present invention; and Fig. 8 is a detailed side view of the arrangement shown in Fig. 5.

With reference to Fig. 1, it can be seen that the heel guard comprises basically a mild steel rectangular cross sectioned sheath 2 of welded construction, having a base plate 4, two side walls 6 and 8, and a top plate 10. The side walls 6 and 8, extend to the rear of the guard 2, to form fixing portions 12 and 14. The base plate 4 extends to the rear of the guard 2 to a greater extent than the top plate 10.

The side wall fixing portions 12 and 14 comprise fixing apertures 16 and 18, through which a fixing pin 20 is insertable. The fixing pin itself comprises a locking aperture 22 in which a locking pin 24 is engageable.

The heel guard 2 also comprises a vertical cut out slot 26 which extends down the width of the side wall 6.

To fit the heel guard 2 to a load fork 28, the heel guard 2 is slipped over the end of the load fork blade 30 and is manoeuvered into position over the heel area of the load fork 28. The base plate 4 then covers the base of the heel area 32 of the fork, and the rear of the top plate 10 contacts the inner bend 34 of the heel, to prevent any further movement along the fork. The fixing pin 20 is then inserted through the fixing aperture 16, behind the load fork 28 and out through the second fixing aperture 18. The fixing pin is then locked into position by the engagement of the locking pin 24 in the locking aperture 22.

With the guard 2 in position over the heel area of the load fork 28, when a fork lift truck operator scrapes the load forks across the ground, the base plate 4 of the guard 2 protects the load fork heel 32. It will be appreciated that only the heel guard 2 will in due course need replacement due to wear rather than the entire fork lift load fork 28 as is conventional. The cost of a heel guard, is only a frction of the cost of an entire fork, and therefore the use of this sacrificial item will amount to a considerable saving in running costs for fork lift trucks.

As a fork lift truck in the main has two load forks, it is preferred that the heel guards are provided and used in sets of two.

A feature which allows a load fork to be readily inspected is the inspection slot 26. An inspector can measure the width of the heel area 32 of the fork 28 without removing the protector 2 by use of this slot 26. Further, because of the cut away nature of the top plate 10 at its rear, the inner bend of the heel area 32 can also be inspected without removal of the protector 2. This area requires regular inspection for stress cracks and other indicators of future fork failure.

It will be appreciated that the base of the guard 2 is preferably of a thicker construction than the remainder of the wall portions of the sheath 2, as it is the base plate 4 which will be subject to wear. To this end, an additional wear plate may be permanently attached to the base 4 of the sheath to create a more hard wearing protector.

To avoid replacement of the heel guard as a whole, replaceable wear pads 38 may be provided. In a further embodiment, illustrated in Fig. 4 the sheath 2 comprises frusto-conical bolting apertures 34 in the base plate 4 and circular insertion apertures 36 in the top plate 10. The wear pads 38 comprise threaded bolting holes 39, and to attach replaceable wear pads to the sheath 2, bolts are inserted through the insertion apertures 36 and screwed into the recesses 34 and 39 to interengage the sheath 2 and wear pad 38. Two further bolts could be used to attach the wear pad 38 at the rear of the sheath 2.

In this embodiment, as the sacrificial wear pads 38 are worn away through use they can be replaced to provide wear protection for the load forks without the need for replacement of the sheath 2. It is thought that in this embodiment, replacement will be less expensive than the case in the alternative embodiment, for which the entire sheath 2 will require replacement when the base plates 4 are worn through.

Fig. 5 shows a further embodiment of heel guard which allows a tight fit of the guard to the load fork heel to be obtained.

The guard comprises a carriage plate 40 of high tensile aluminium bronze, which is of a substantially L-shaped cross section with an inner surface corresponding roughly to that of the outer surface of the heel corner 42.

The carriage plate 40 comprises an upstanding section 44 and a horizontal section 46. The horizontal section 46 embodies spaced bolt holes for accepting bolts 48 which engage a hardwearing plate protector 50 in position below the carriage.

The hard wearing plate 50 is made of hardened high carbon steel, and the lower surface of the plate 50 is provided with a number of transverse "stelite" weld lines 52, which greatly increase the durability of the plate. Furthermore, the front protruding portion 54 of the hard-wearing plate 50 is upturned towards the load fork to deflect objects moving towards the protector.

As well as attachment by the bolts 48, the hard-wearing plate 50 may be adhered to the carriage plate 40 additionally by means of double sided adhesive shock absorption pads, as produced by the company 3M.

An engaging recess 56 is provided behind the wear-prevention plate 50, wherein the lower portion of a stainless steel securing ring 58 is insertable, and in addition the upstanding portion 44 is adapted to accommodate perpendicularly a pair of stainless steel securing load screws 60.

The protector 50 is attached to the load fork 28 by first placing the securing ring 58 via the free end of the load fork at the corner portion 32 of the heel, and with the securing load screws 60 screwed outwards from the carriage 40 which, along with the hard-wearing plate 50 immovably attached thereto and a Neoprene cushion 62 inserted between the carriage 40 and the load fork 28, can be positioned between the base of the securing ring 58 and the load fork 28. At this point, the guard is loosely positioned, and in order to removably attach it to the load fork, the securing load screws 60 are screwed inwards of the carriage 40 so as to abut tightly against the rear surface 64 of the load fork shank, and secure the guard in place.

The advantages of this construction of device are manifold, in that it may be used with a variety of configurations of load fork, the adjustment of the securing load screws 60 being the only requirement for immovable placement of the plate 50 on the load fork, and furthermore it will be seen that the upper surface 66 of the load fork is minimally obstructed by the placement of the protector, the obstruction occuring due to the positioning of the securing ring around the load fork occurs only in the curved portion 32 of the load fork heel.

An alternative construction of securing ring 68 for use in the heel guard embodiment of Fig. 5 is shown in Fig. 6. In this embodiment, the securing ring 68 consists of two halves 70, 72 which may be threadingly connected by means of two elongate nuts 74, 76. The ends 78 and 80 of the securing ring 70 are provided respectively with left-handed and righthanded threads and the ends 82 and 84 are similarly threaded, such that when the nuts 74 and 76 are engaged with the respective ends, the width of the securing ring 68 may be altered merely by rotating the elongate nuts 74, 76 in suitable directions. This provides the elongate guard with further flexibility in use, and allows the heel guard to be efficiently used with a larger variety of load fork shapes and sizes.In use, the securing ring 68 is tightened suitably, and subsequently the load screws 60 are tightened to lock the guard in place.

A further embodiment of a heel guard is shown in Fig. 7, and this heel guard 86 is suitable for use with load forks which prevent use of the previously described embodiments, for example where the load fork has an incompatable feature 90 on the rear surface 64 of the load fork shank 88. The guard 86 is positioned in front of the load fork shank 88, and conveniently rests against the front surface of the load fork shank so as to be as unobtrusive and well supported as possible. The guard 86 consists of an adjustable frame 92 which embraces load fork 28, a carriage plate 94, and a replaceable hard wearing protector plate 96 which is secured to the carriage plate 94 by means of replaceable securing bolts 98 much as previously described in relation to the alternative embodiments.The frame 92 has a support bar 98 solidly welded to the vertical supports 102, the horizontal support 98 threadingly supports two co-acting bolts 104, 106, which as best illustrated in the side view of Fig. 8, rest at their lower end against a load bar 108. The load bar 108 is of an L-shaped cross section, and is solidly welded to a guide bar 110, which moves in vertical slots 112, 114 formed in the vertical supports 102. Thus, by screwing down the bolts 104, 106 (which have alan-key heads for ease of use) the vertical disposition of the load bar can be altered, and the guard can be securely placed in its location immediately in front of the fork shank 88 once correctly sighted and fitted, locking nuts 116 and 118 are screwed upwards to abut against the underside of the horizontal support 98 which secures the guard against future movement and loss of grip.

Finally, a cover 120 is placed over the front of the guard 86 to protect the guard from damage.

Further aspects of the present invention include the use of a wear plate which might be bonded directly by adhesive means to the base of a load fork heel, and although it has been found that the provision of stelite welds directly to the base of the load fork heel cause severe embrittlement of the load fork to such an extent that the load fork is impractically weakened by this process, other hardening or protective material or processes may be applied directly to the base of the load fork heel during or after manufacture thereof to achieve the effect of the invention.

Furthermore, although at present load fork manufacturers make no provision for the attachment of wear prevention means to the heel area of their products, according to a further aspect of the present invention, bolt holes, flanges, hooks or the like may be provided on a load fork heel whereby a sacrificial protective plate or other wear reduction means may be removably attached to the underside of the fork heel to increase the working lifespan of a load fork.

The above described embodiments serve only to illustrate the present invention, and it will be appreciated that any wear reduction means, either sacrificial or non-sacrificial, for example in the form of rollers, may be utilised at the heel section of a load fork in order to achieve the present invention, and to enjoy its certain advantages.

Claims

1. A guard for a load fork, comprising a load fork wear protector and fixing means whereby the said protector can be attached below the heel area of the load fork.

2. A guard according to claim 1 wherein the fixing means are such that the said protector is replaceable.

3. A guard according to claim 1 or 2 wherein the protector comprises a sacrificial wear means.

4. A guard according to claim 1, 2 or 3 wherein the said fixing means is adapted to embrace the load fork.

5. A guard according to claim 4 wherein the fixing means comprises a threaded member for adjusting the embrace of the fixing means.

6. A guard according to claim 4 or 5 wherein the fixing means comprises a securing ring which embraces both the load fork and the protector.

7. A guard according to claim 6 wherein the securing ring consists of two portions threadingly connected by one or more elongate nuts such that, on turning the said one or more elongate nuts, the size of the securing ring changes.

8. A guard according to any of claims 4 to 7 wherein the fixing means comprises abutment means adapted to act against the rear of the fork shank.

9. A guard according to claim 8 wherein the said adjustment means comprise one or more securing load screws which are threadingly mounted so that fitting adjustment can be effected by adjustment thereof.

10. A guard according to any of claims 1 to 9, wherein the guard comprises a sheath of rectangular cross section.

11. A guard according to claim 10 wherein the said sheath comprises side walls which protrude from the rear of the load fork when positioned.

12. A guard according to claim 11 wherein the said side walls comprise recesses or apertures wherein a fixing means is engageable to fix the sheath in place over the load fork heel.

13. A guard according to any of claims 10 to 12 wherein the sheath comprises a vertical slot in one side thereof to allow for heel wear measurement, without the need for removal of the heel guard.

14. A guard according to any of claims 2 to 13 wherein the protector is removably secured to a carriage means.

15. A guard according to any of claims 1 to 14 comprising shock absorption means in the form of a cushion located intermediately of the protector and the load fork.

16. A guard according to any of claims 3 to 15 wherein the protector is in the form of a hard-wearing plate.

17. A guard according to claim 16 wherein the said plate is made from hardened and tempered high carbon steel.

18. A guard according to claim 16 or 17 wherein the said plate is provided with "stelite"}wemd sections transversely disposed along its underside.

19. A guard according to any of claims 16 to 18 wherein the said plate has a diagonally upturned portion projecting forwardly, to deflect objects impinging upon the guard.

20. A guard substantially as hereinbefore described, with reference to the accompanying diagrams.