GB2501698A

GB2501698A - Load-spreading foot for jack-stabilised plant

Info

Publication number: GB2501698A
Application number: GB1207558.6A
Authority: GB
Inventors: Gordon Charles Leicester; Jonathan Warburton Orrell
Original assignee: ZT SAFETY SYSTEMS Ltd
Current assignee: ZT SAFETY SYSTEMS Ltd
Priority date: 2012-05-01
Filing date: 2012-05-01
Publication date: 2013-11-06
Anticipated expiration: 2032-05-01
Also published as: GB2501698B; GB201520794D0; GB2529354B; GB2529354A; GB201207558D0

Abstract

A load-spreading foot 4 for jack-stabilised plant equipment, including, as viewed from above, a recess 18, which may accommodate steering rotation of an adjacent vehicle wheel. The perimeter 8 of the foot may have a convex rolling portion, and the foot may have hand holds 46 adjacent to the perimeter 8 to facilitate handling and rolling of the foot. The foot may include a magnet 26 secured by adhesive in an aperture 22 so as to secure a jack base in position. The aperture 22 may be surrounded by upwardly extending projections 32 separated by gaps 36 to facilitate the removal of magnetic debris from the magnet 26. The foot may be designed to come away from the jack base when knocked for example during manoeuvring of plant equipment so as to avoid damaging the jack or the foot.

Description

LOAD-SPREAD ING FOOT

[0001] The present invention relating to a load-spreading foot for an item of jack-stabilised plant equipment such as a mobile elevated work platform, crane or so-called HIAB lorry.

The use of the foot is not restricted to such applications however and could be used with any type of plant equipment that includes stabilisation jacks.

[0002] The problem to be overcome and the invention will be described with particular reference to a mobile elevated work platform, referred to hereafter simply as a mobile platform, but could be used with other types of jack stabilised plant.

A mobile platform comprises a powered vehicle on which an elevatable platform is mounted. To increase stability, jacks means, usually four, are provided each of which can be firstly extended to move a ground engaging base of the jack means away from the vehicle and secondly extended so that a base thereof is moved downwardly to engage a ground or floor surface. To enable the jack to be retractable to a position close to the vehicle when not in use, for example when the mobile platform is being driven over a long distance, the base of the jack needs to be relatively small. A consequence of the base being relatively small is that, for many ground and floor surfaces, the load per unit area exerted by the base is too great unless some form of load-spreading pad is provided beneath the base. One way that this problem has been addressed in the past has been to provide a load-spreading pad with members on its upper surface defining a channel allowing the load-spreading pad to be slid laterally into engagement with the base by engaging the base in the channel. Since it is desirabTh for the base of the jack means to bear down on the load-spreading pad centrally, the pad, which is typically circular in or square, has a significant lateral extent protruding away from the base of the jack means towards the vehicle. When there is a requirement to move the mobile platform from one part of a site to another it is customary to retract the jack means so as to draw the foot in towards a main body of the mobile platform, thereby rendering the mobile platform more manoeuvrable in confined spaces. The lateral extent of the pad referred to above however limits the extent to which the base can be drawn in towards the main body, particularly in situations in which the base is drawn in towards a wheel of the mobile platform which may be a steerable wheel.

[0003] In practice, since such load-spreading pads are not convenient to use, it is quite common for mobile platforms to be used without adequate load spreading pads which can lead to damage to a floor on which the mobile platform is used and/or inadequate stabilisation when the mobile platform is used on soft ground.

[0004] An object of the invention is to provide a load-spreading pad or foot for use in such situations that at least partly overcomes the above problem.

[0005] Thus according to a first aspect of the invention there is provided a load spreading foot for jack stabilised plant equipment the foot having a lateral periphery including, as viewed from above, a recess and a projecting portion on each side of the recess, a support surface engaging face of the foot having a centre of area. Such a foot can be positioned with its recess facing an adjacent wheel on the mobile platform so that, when a jack means to which it is connected is moved in towards a main body of the mobile platform, it can be brought relatively closer thereto as a consequence of a portion of the wheel being accommodated in the recess. In certain circumstances a sole operator of a mobile platform may, without descending from the elevatable platform itself, effect retraction of the jack means and drive the vehicle to a different location. The recess can be arranged to accommodate steering rotational movement of an adjacent wheel.

[0006] Preferably the foot includes jack locating means in order to facilitate correct positioning of the foot relative to the base of the jack means.

[0007] To reduce the chance of the foot canting over at an angle when used on soft ground, preferably a centre of the jack locating means is at least substantially aligned with the centre of area of the support surface engaging area of the foot.

[0008] Preferably over a sector subtending 80' at the centre of area and centrally located with respect to the recess, a first average radial distance ray from the centre of area to the periphery is less than a second average radial distance Ray from the centre of area to other parts of the periphery.

More preferably r3< 0.7 Ray.

[0009] conveniently the periphery may be substantially heart shaped.

[0010] In view of the load that the foot may be required to support its overall weight may be more than a single worker could easily carry. When the foot is disposed perpendicular to a support surface and rolled, it engages the support surface along a rolling portion of the periphery. Preferably the rolling portion of the periphery is at least substantially convex. Such a form will facilitate movement of the foot by rolling by a single worker thereby obviating the need to lift the foot clear of the ground.

[0011] Since vertical shear and bending forces in the foot will be less towards its periphery and to reduce its overall weight, preferably a height of the foot is a maximum at a region around the centre of area and tapers to a lower height towards the periphery.

[0012] preferably the foot includes hand-grip recesses situated adjacent to the periphery to facilitate handling and manoeuvring of the foot.

[0013] The invention also provides a plant vehicle including plural wheels and at least one foot as set out above situated such that a portion of one of the wheels is accomrrLodatable in the recess. More preferably steering rotation movement of the wheel is accommodated by movement of a portion of the wheel within the recess.

[0014] As mentioned above, when a sole operator of a mobile platform wishes to move the mobile platform on a site it is customary for the jack means to be retracted. If a load-spreading pad not connected to the jack means is used, the operator will need to descend from the elevatable platform to reposition the load-spreading pad. On the other hand where the load-spreading pad is connected to the base of a jack means, even though it may be possible to lift the load-spreading pad with the base of the jack means, there is a possibility that the load-spreading pad may hit an obstruction when the mobile platform is being driven to a new location. This in turn can lead to the load-spreading pad or the jack means or both becoming damaged.

[0015] A second object of the invention is to provide a load-spreading pad or foot which overcomes the above disadvantages.

[0016] Thus according to a second aspect of the invention there is provided a load-spreading foot for jack stabilised plant equipment the foot including releasable connection means for releasably connecting the foot to a lower end of a jack, the releasable connection means including a magnet and the connection means is magnetic. With such a magnetic connection means it is possible to quickly and easily connect the foot to a base of a jack means or disconnect if therefrom without needing any supplementary fastening means or tools.

Furthermore in the event of the foot being knocked, the foot will become detached from the jack means, thereby avoiding the possibility of the foot or the jack means sustaining damage - [0317] Preferably the connection means includes lateral restraint means for limiting lateral movement of the foot relative to a base of a jack. With such an arrangement, when the foot is knocked, rather than simply translating relative to the base of the jack, it will quickly become detached therefrom. Conveniently the lateral restraint means includes at least one locating projection which projects upwardly from an upper surface of the foot.

[0018] So as to facilitate the removal of debris, and in particular magnetic debris, which may become attracted to the magnet and become magnetically adhered to a jack engaging surface of the foot, preferably the foot includes plural said locating projections with gaps therebetween which extend down to a jack engaging surface of the foot. Such debris may be slid along the jack engaging surface and away from the magnet through the gaps.

[0019] conveniently the magnet is accommodated in a recess in a body of the foot. This will help to protect the magnet from becoming damaged.

[0020] Preferably the magnet is connected to a bcdy of the foot by adhesive means. By using adhesive to secure the magnet, fastener apertures in the magnet, which would provide stress concentration points can be avoided. Due to the high loads that the foot will be subjected to, the presence of stress concentration points in the magnet would increase the chance of the magnet fracturing when the foot is loaded.

[0021] conveniently the adhesive means includes a pad with adhesive on opposed sides thereof.

[0022] It should be noted that any features described in connection with the first aspect of this invention could be used in connection with the second aspect of the invention.

Furthermore any features described in connection with the second aspect of the invention could be used in connection with the first aspect of the invention.

[0023] The invention will now be described by way of example only with reference to the accompanying drawings in which: [0024] Fig 1 is a plan view from above of a load-spreading foot according to both first and second aspects of the invention.

[0025] Fig 2 is a cross-section on the line 2-2 of the foot shown in Fig 1.

[0026] Fig 3 shows schematically the foot illustrated in Figs 1 and 2 magnetically connected to a jack; and [0027] Fig 4 is a schematic view from above of the foot shown in Figs 1 to 3 in close proximity to a steerable wheel.

[0028j A load-spreading foot 4 according to the invention is shown in plan view from above in Fig 1. The foot 4 includes a body 6 which can be made from any suitable material such as fibre reinforced plastic or metal such as steel or aluminium alloy. The body has a first height h1, at its centre and tapers towards a shorter height h2 at a periphery 8. As viewed from above, as in Fig 1, the body 8 may have a substantially heart shaped form.

[0029] The body has a ground or floor engaging lower face 10 having a centre of area 12 located on a central axis 14. The centre of area 12 is defined as a point through which any line, such as line 16 shown in Fig 1, can be drawn wherein equal areas of lower face 10 are present on opposed sides of the line 16.

[0030] The periphery 8 of the body 6 is generally convex apart from a portion of the periphery 8 between locations marked X and Y in Fig 1. In this area the periphery 8 defines a recess 18 where the periphery 8 becomes closer to the central axis 14. On either side of the recess 18 the periphery 8 defines a projecting portion 19. In the embodiment shown the entire portion of the periphery not forming the recess 18 is convex and constitutes a rolling portion of the periphery along which the foot can be rolled.

Hand-hold recesses 46 are provided in the upper surface 24 and adjacent to the periphery 8 to facilitate handling of the foot.

[0031] Over a sector 20 subtending an angle of 80and centred with respect to the recess 18 the average radial distance r of the periphery 8 from the central axis 14 is

B

ray. The average radial distance R of the remainder of the periphery (i.e. outside the sector 20)is Ray. In the embodiment shown: ray = 0.6 Ray. Preferably ray < 0.7 Ray.

[0032] An aperture 22, centred on the central axis 14, is provided in an upper surface 24 of the body 6. A disc shaped magnet 26 is accommodated in this aperture 22. The magnet has high magnetic and mechanical strengths. The magnet 26 is held in the aperture 22 by adhesive securing means. This securing means is in the form of an adhesive pad 28 in the embodiment shown, which has an adhesive layer 30 on each side thereof.

[0033] While a single magnet 26 in a single aperture is shown, alternatively plural magnets could be provided in one or more apertures. Furthermore while the magnet 26 and the aperture 22 shown are circular, other shapes would be possible.

[0034] Locating projections 32 extend upwardly from the upper surface 24 of the body 6. These projections also extend upwardly above a jack engaging surface 34 of the foot 4. These projections 32 are situated around an edge of the magnet 26. The projections 32 are separated by gaps 36 which extend down at least to the jack engaging surface 34. These gaps provide a route through which magnetic debris can be slid off the jack engaging surface 34. The locating projections 32 provide lateral restrain of a jack relative to the foot 4.

[0035] The load-spreading foot 4 according to invention is shown magnetically connected to a jack 38 of a mobile platform in Fig 3 from which it can be seen that the locating projections 32 will limit lateral movement of the load-spreading foot relative to a jack base 40. When the jack 38 is adjacent to a wheel 42 of a mobile platform the foot 4 will be positioned with the recess 18 facing the wheel as shown in Fig 4. In this manner, when the jack 38 is retraced in the direction D shown in Fig 4 the central axis 14 of the foot 4 can be brought close to the wheel, without impeding its steering rotational movement, as shown with broken lines in Fig 4.

[0036] If the foot 4 needs to be lowered into contact with the ground while it is still close to the wheel 42, due to the presence of the projecting portions 19, the centre of area 12 of the lower face 10 of the foot 4 will still be aligned with a central axis 44 of the jack 38.

[0037] When a mobile platform is being moved with a foot 4 magnetically connected to the jack 38, if the foot 4 is knocked, as the locating projections 32 prevent any significant lateral displacement of the foot 4 with respect to the jack foot 40, the foot 4 will be knocked off the jack thereby preventing the foot 4 or jack 38 from becoming damaged.

[0038] While the two aspects of the invention have been described with particular reference to a specific embodiment it will be clear to a skilled person in the art that modification to the embodiment could be made without departing from the scope of the appended claims.

Claims

CCLAIMS1. Load-spreading foot for jack stabilised plant equipment the foot having a lateral periphery including, as viewed from above, a recess and a projecting portion on each side of the recess, a support surface engaging face of the foot having a centre of area.
2. The foot of claim 1 including jack locating means.
3. The foot of claim 2 wherein a centre of the jack locating means is at least substantially aligned with the centre of area.
4. The foot of any preceding claim wherein over a sector subtending 80 at the centre of area and centrally located with respect to the recess, a first average radial distance ray from the centre of area to the periphery is less than a second average radial distance Ray from the centre of area to other parts of the periphery.
5. The foot of claim 4 wherein: r< 0.7 Ray
6. The foot of any preceding claim wherein the periphery is substantially heart shaped.
7. The foot of any preceding claim wherein, when the foot is disposed perpendicular to a support surface and rolled, it engages the support surface along a rolling portion of the periphery, the rolling portion of the periphery being at least substantially convex.UB. The foot of claim 7 wherein all of the rolling portion of the periphery is convex.9. The foot of any preceding claim wherein a height of the foot is a maximum at a region around the centre of area and tapers to a lower height towards the periphery.10. The foot according to any preceding claim including hand-grip recesses situated adjacent to the periphery.11. A plant vehicle including plural wheels and at least one foot as claimed in any preceding claim arranged such that a portion of one of the wheels is accommodatable in the recess.12. A plant vehicle as claimed in claim 11 wherein steering rotation movement of thc wheel is accommodated by movement of a portion of the wheel within the recess.13. A foot or foot of a plant vehicle as claimed in any preceding claim further including the features claimed in any of the fol*owing clams 14 to 22.14. A load-spreading foot for jack stabilised plant equipment the foot including releasable connection means for releasably connecting the foot to a lower end of a jack, the releasable connection means including a magnet and the connection means being magnetic.15. The foot according to claim 14 wherein the connection means includes lateral restraint means for limiting lateral movement of the foot relative to a base of a jack. J216. The foot according to claim 15 wherein the lateral restraint means includes at least one locating projection which projects upwardly from an upper surface of the foot.17. The foot according to claim 16 wherein the foot includes plural said locating projections with gaps therebetween which extend down to a jack engaging surface of the foot.18. The foot according to any of claims 14 to 17 wherein the magnet is accormiodated in a recess in a body of the foot.19. The foot according to any of claims 14 to 18 claim wherein the magnet is connected to a body of the foot by adhesive means.20. The foot according to claim 19 whercin the adhesive means includes a pad with adhesive on opposed sides thereof.21. The foot according to any of claims 14 to 20 including hand-grip recesses situated adjacent a periphery of the foot.22. The foot according to any of claims 14 to 21 further including the features claimed in any of claims 1 to 9.