GB2222996A - Lifting device for tractor; lifting attachment - Google Patents

Abstract

The device is of the kind having an upright column 1, the lower end of which is provided with means for attachment to the three-point linkage of a tractor, and a jib 2 pivotally coupled to the upper end of the column. The jib carries a hook 33 at its free end, and a ram 35 extends between the column and a pivot 34 disposed part-way along the jib. The vertical depth of the jib 2 progressively increases between the hook and the pivot 34, and then decreases again towards the column. The jib is of box section and is formed of a pair of side walls provided with inturned flanges welded together. A lifting attachment for use with the device comprises a horizontal H-shaped frame having a central lifting pin 46 for engagement with the hook 33 and spaced lugs 48 for engagement with a tillage bag. <IMAGE>

Description

LIFTING DEVICE This invention is concerned with lifting devices of the kind intended primarily, though not exclusively, for lifting tillage bags, and comprising an upright column, the lower end of the column being provided with means for attachment to the three-point linkage of a tractor, a jib pivotally coupled at one end to the upper end of the column, the jib carrying a depending hook at its free end, and a ram extending between a first pivot disposed part way along the length of the column and a second pivot disposed part-way along the length of the jib.

In such devices there is a need to hold the bag as far away from the tractor as possible in order to handle the bags efficiently, but on the other hand any increase in the length of the jib tends to increase its weight, particularly since the strength of the jib must be increase accordingly, and the risk of the tractor overturning is thus increased.

In an existing device of this kind which is currently on the market the ji.b i.s formed of two telescopic parallel sided box section members so that its length can be reduced for lifting particularly heavy loads.

This is considered unsatisfactory i.n many respects, mainly because an attempt might inadvertently be made to lift a heavy load with the jib extended.

One object of the present invention is to enable the length of the jib to be optimised with the smallest posible increase in weight. and reduction in strength of the jib.

According to the present invention, in a lifting device of the kind speci.fied in the openi.ng paragraph above, the vertical depth of the jib progressively increases between the hook and the region of the second pivot.

The weight of the ji.b may also be reduced wi.thout significant reduction in strength if the vertical depth of the jib progressively decreases from the region of the second pivot towards the column.

The j]E is preferably of box section and for ease of manufacture might comprise a pair of side wall portions provided with inturned flanges formi.ng the top and bottom walls, the two portions being secured together by welds.

The invention includes, for use with a lifting device of the kind specified in the opening paragraph above, a lifting attachment comprising means for engagement with the hook of the lifting device, a rigid structure depending from the said engagement means and lying in a generally horizontal plane, and the structure being provi.ded with a plurality of attachment means for attachment to an article to be lifted and spaced horizontally about the said engagement means.

The invention will now be exemplifi.ed i.n the following description to be read in conjunction with the accompanying drawings in which: Figure 1 is a side view of a lifting device in accordance wi.th the invention, Figure 2 is a rear view of the device, Figure 3 is an exploded perspective view of the jib of the device, and Figure 4 is a perspective view of a lifting attachment for use with the device.

Referring to Fig.s 1 and 2, the lifting device comprises an upright column 1 of rectangular box section and a jib 2, also of box section, pi.votally connected at. one end to the upper end of the column so as to project in a forward direction transverse to the column.

The bottom of the column 1 is perpendicularly secured to the centre region of a horizontal beam 3. Bracing bars 4, 5 join the opposi.te ends of the beam 3 to a point approximately one third of the way up the column 1. Beam 3 and bars 4 and 5 are all of box section. A pair of spaced parallel flanges 6 extend rearwardly from opposite ends of beam 3 and these carry aligned outwardly projecting pins 8, 9 for connection with the two lower linkage points of a conventional three point li.nkage at the rear of a tractor (not shown). Part way up the column 1, in the region of its junction wi.th bracing bars 4, 5, two spaced apertured plates 10 project rearwardly for connection wi.th the upper link of the three point linkage.

At the top end of the column another pair of spaced parallel plates 14 are welded to each side of the column projecting forwardly, and these are apertured to recei.ve a pi.vot pin 16. This pin passes through the rear end of the jib 2, which will now be described in more detail.

As shown in Fig. 3, the jib is formed of two main parts 18, 19. Each part comprises an elongate side wall 20 with a straight lower edge 21 and perpendicular front and rear ends 22, 23. The upper edge of each wall 20 comprises two portions 24 and 25 which are each inclined away from the end walls to meet at an apex 26.

However, portion 24 is longer than portion 25 so that the apex 26 is positioned about two thirds of the way along the jib. Edge portions 24 and 25 and lower edge 21 of the two parts are provided with facing inturned flanges 27-29 which are welded together along their meeting edges to join the two parts 18, 19 together.

Referri.ng back to Fig. 1, a pair of spaced parallel plates 31, 32, are partly i.nserted into the open front end of the ji.b 2. These plates are welded i.n posi.tion and a depending hook 33 i.s pivotally affixed between the forwardly projecting ends of the plates. A similar pair of plates (not shown) are welded into the open rear end of the jib to receive the pi.vot pin 16. The insertion of the plates into the box section of the jib ensures that they are of suffici.ent strength to withstand the loads to which they are subjected in use.

A pair of depending flanges 34 are welded to the underside of the jib 2 immediately beneath the apex 26, and one end of an hydraulic ram 35 is pivotally coupled between these flanges. The opposite end of the ram is pivotally coupled between a further pair r of spaced parallel flanges 36 secured to the front face of the column 1 about two thirds of the way up the column.

The lifting frame shown in Fig. 4 comprises a cross beam 41 and two end beams 42, 43, all of box section, secured together in a horizontal H confi.gurati.on. Two plates 44, 45 are upstanding from opposite sides of the cross beam 41 and these are bridged by a lifting pin 46 located half way along the cross beam and spaced above i.t. The four ends of the beams 42 and 43 are each provi.ded with an upstanding lug 48.

With the device secured to the three point linkage of a tractor and the ram coupled to the hydraulics of the tractor, a tillage bag can be coupled to the hook 33 and the ram extended to pivotally raise the jib. If it is required to lift a larger tillage bag of the rectangular type the hook i.s engaged with the pin of the lifting frame and the four li.fting sli.ngs provided at the four corners of the container are looped over the ends of the beams 42, 43 and engaged wi.th the lugs 48. The bag can then be lifted and moved around as required. The frame avoids the need to couple the bags to the hook 33 by chains so that the vertical di.stance between the bag and the jib 2 is s reduced, thereby providing a greater lift.

The shape of the jib allows the load to be held as far away from the tractor as possi.ble without reducing the strength of the jib and with minimal increase i.n its wei.ght.

Claims (8)

1. A lifting device comprising an upright column, the lower end of the column being provided with means for attachment to the three-point linkage of a tractor, a jib pivotally coupled at one end to the upper end of the column, the jib carrying a depending hook at its free end, and a ram extending between a first pivot disposed part way along the length of the column and a second pivot disposed part-way along the length of the jib, the device being distinguished by the fact that the vertical depth of the jib progressively increases between the end which carries the hook and the region of the second pivot.

2. A device according to Claim 1, in which the vertical depth of the jib progressively decreases from the region of the second pivot towards the column.

3. A device according to Claim 1 or 2, in which the jib is of box section and comprises a pair of side wall portions provided with inturned flanges forming the top and bottom walls, the two portions being secured together by welds.

4. A device according to Claim 1, 2 or 3, in which the jib is of box section and the hook is suspended between a pair of spaced, substantially parallel plates which are secured within an open front end of the jib.

5. A lifting attachment which is suitable for use with a lifting device according to any preceding claim, the attachment comprising means for engagement with the hook of the lifting device, a rigid structure depending from the said engagement means and disposed in a generally horizontal plane, and the structure being provided with a plurality of attachment means for attachment to an article to be lifted, the attachment means being spaced horizontally about the said engagement means.

6. A lifting atachment according to Claim 5, in which the rigid structure is substantially H-shaped.

7. A lifting device substantially as described with reference to Figures 1 to 3 of the drawings.

8. An attachment substantially as described with reference to Figure 4 of the drawings.