GB2031976A - Improvements in post driving apparatus - Google Patents

Abstract

Post driving apparatus comprises an elongate guide 13 having means 11 for pivotally connecting one end of the guide to a support located above the ground so that, in use, the guide is suspended from the support and extends downwardly therefrom with the lower end of the guide spaced above the ground. A suspended weight 14 is movable up and down in the guide 13, and a ram driven linkage 18, 19, 23 effects upward movement of the weight, so that when the weight falls the post, the upper end of which is located in the lower end of the suspended guide 13, is driven by the impact of the weight on the upper end of the post. <IMAGE>

Description

SPECIFICATION Improvements in post driving apparatus The invention relates to post driving apparatus and sets out to provide a form of apparatus which may be readily attached to a farm tractor or other vehicle and which may be rapidly set up to drive each post, thus increasing the rate at which posts may be driven.

Known forms of post driver for attachment to tractors usually comprise a support structure which, in use of the post driver, rests on the ground and carries an upwardly extending guide for a heavy weight which is movable upwardly on the guide, usually by a hydraulically powered transmission, and is then dropped downwardly on the guide so as to strike the upper end of a post, the lower end of which rests on the ground. In these known forms of post driver the guide has to be accurately aligned with the post and usually some form of holding device is provided to locate the posts in relation to the guide and support structure.Due to the necessity of basing the support structure firmly on the ground, and of locating the post accurately with respect to the support structure, the tractor must be manoeuvred to a fairly precise position in relation to the desired position of the-post before post driving can begin. Such manoeuvring of the tractor and setting up of the driver is a timeconsuming business, and difficulty may be experienced in setting up the apparatus and driving the post vertically if the ground is not level.

According to the invention there is provided post driving apparatus comprising an elongate guide having means for pivotally connecting one end of the guide to a support located above the ground so that, in use, the guide may be suspended from the support and extend downwardly therefrom with the lower end of the guide spaced above the ground, means on at least the lower end of the guide for locating the lower end of the guide in relation to the upper end of a post to be driven, a weight movable up and down on the guide, and means for effecting said up and down movement of the weight on the guide.

With an arrangement according to the invention, the support carrying the apparatus, which support will usually be mounted on a vehicle, is simply brought to a position where the lower end of the suspended guide engages the upper end of the post to be driven, whereupon the post is then driven by the weight falling down the guide and impacting on the upper end of the post. Since the apparatus is suspended, it will automatically adopt the required vertical position, regardless of any unevenness or slope of the ground on which the vehicle is standing.

The support may be movable up and down so that the guide may be lowered into engagement with the top of the post and, if required, move downwardly with the post as the post is driven into the ground.

Preferably, however, the guide is provided with a lateral opening or slot so that it may be swung sideways to surround the upper part of the post.

The guide may be pivotally suspended on the free end of a swinging arm mounted on the vehicle, for example mounted on the three point linkage of a tractor.

The guide may comprise a frame, open at least at the lower end thereof, within which frame the weight is movable up and down. Preferably the weight is suspended on a flexible element and power means are provided for hoisting the weight upwardly on the flexible element and allowing it to fall rapidly to impact on the upper end of a post located within the lower end of the suspended guide frame.

The power means may comprise a hydraulic ram connected through a linkage to the flexible element so that upon extension of the ram the weight is hoisted upwardly by the flexible element and upon contraction of the ram the weight falls downwardly.

The linkage may comprise a pivoted lever to one end of which the ram is connected and the opposite end of which is connected to the flexible element. Preferably the ram is connected to the lever at a closer distance from the pivot thereof than is the flexible element.

The following is a more detailed description of various embodiments of the invention, reference being made to the accompanying drawings in which: Figure 1 is a vertical section through a post driving apparatus, Figure 2 is a view looking from the left of Figure 1, Figure 3 is a plan view of the apparatus of Figures 1 and 2, Figure 4 is a view of an alternative form of apparatus for mounting on a tractor, looking from the rear of the tractor, and Figure 5 is a plan view of the apparatus of Figure 4.

Referring to Figures 1,2 and 3, the apparatus comprises a unit designed to be suspended by means of a pivot point 11 to a support (not shown).

The support may comprise a conventional power arm mounted on a tractor or other vehicle for upand-down and lateral swinging movement relatively thereto, or may simply comprise a fixed support arm. The unit is, in use, suspended from the power arm or support arm with its lower end spaced above the ground.

The unit 10 comprises two spaced parallel upper support plates 12 welded to the upper end of a vertical hollow cylinder 13, of circular cross-section. The hollow cylinder 13 serves as a guide for a heavy cylindrical weight 14 which is slidable up and down within the cylinder. An abutment ring 15 can be welded within the lower end of the cylinder 13, as shown, to limit the downward movement of the weight 14 within the cylinder. One end of a chain 16 is connected to a lug 17 on the upper side of the weight 14, and extends upwardly through the cylinder 13 and passes over a pulley wheel 17 rotatably mounted on a shaft extending between the plates 12.

After passing over the pulley wheel 17, the chain 16 passes around a further pulley wheel 18 rotatably mounted on one end of an L-shaped lever arm 19, the end of the chain 16 then being anchored to a fixed bar 20 extending between the plates 12.

The L-shaped lever arm 19 is pivotally mounted at 21 between parallel plates 22 welded to the side of the cylinder 13. A single or double acting hydraulic ram 23 has the end of its cylinder pivotally connected at 24 between the lower ends of the plates 22, and the piston rod 25 of the ram is pivotally connected at 26 to the end of the L-shaped lever arm 19 remote from the pulley wheel 18. The arrangement is such that when the hydraulic ram 23 is extended the L-shaped lever arm 19 is swung anti-clockwise, as seen in Figure 1, and the weight 14 is drawn upwardly within the cylinder 13 by the chain 16.

When the hydraulic ram 23 is actuated in the opposite direction to retract the piston rod 25 (or the pressure is released in the case of a single-acting ram), the L-shaped lever arm 19 swings clockwise and the weight 14 falls rapidly under its own weight.

The pivot point 26 is disposed much closer to the pivot point 21 than is the pulley wheel 18 so that only a comparatively small extension of the ram 23 is necessary to raise the weight 14.

In operation of the apparatus, the vehicle carrying the unit is driven to a position adjacent where a post requires to be driven and the lower end of the unit 10 may be lowered over the top of the post, which is held manually in the required vertical position.

Alternatively, and preferably, the cylinder wall may be provided with a longitudinal slot, open at its lower end, of a width to permit the upper end of the post to pass through the slot, so that the cylinder may be moved sideways into position around the post. Handles may be provided on the outside of the cylinder to facilitate handling. As previously mentioned, due to the unit being suspended from the support arm, it will automatically adopt the required vertical position regardless of any unevenness or slope of the ground on which the vehicle is standing.

Consequently, it is ensured that the post itself will be driven truly vertical.

When the unit is in position over the post the hydraulic ram 23 is repeatedly actuated causing the weight 14to be raised and dropped repeatedly onto the upper end of the post, driving the post into the ground. When the post has been driven into the ground to the required depth, the support arm carrying the unit 10 is raised or swung sideways to disengage the unit from the post, and the vehicle may immediately be driven on to the location of the next post. Thus it will be seen that there is no necessity fortime-consuming setting up of the apparatus before the actual driving of a post can begin.

It may occasionally be necessary or desirable for a post to be driven into the ground at an angle to the vertical. To enable this to be effected, a second hydraulic ram, or other adjustable linkage, may be connected between the support arm and the unit, so that by operating said ram or linkage the unit may be inclined at the appropriate angle to the vertical.

In a modified arrangement, not shown, the hydraulic ram and associated L-shaped lever arm for raising the weight 14 are mounted on the support arm from which the unit 10 is suspended rather than on the unit 10 itself, as shown. In either arrangement the end of the longer arm of the L-shaped lever may be directly connected to the end of the chain 16 instead of the chain passing around a pulley on the lever as shown. However, it will be appreciated that with such an arrangement the end of the lever requires to move twice as far to raise the weight 14 the same distance. This may be compensated for by connecting the ram closer to the pivotal mounting of the L-shaped lever.

Figure 4 shows a modified arrangement in which the unit 10 is supported from a support structure 27 carried by the three point linkage at the rear of a tractor. In this case adjustable ground engaging feet 28, 29 are provided for added stability. The unit 10 is similar to that shown in Figures 1 to 3 but a manually operated locating device 30 is provided on the unit.

This comprises two spring-loaded arms 31 pivotally mounted on opposite sides of the unit and movable, by means of an operating lever 32 carrying a cam, between a free position (shown dotted) in which the unit 10 may be located over the upper end of a post to be driven, and a holding position (shown in full lines) in which the arms 31 are spring-urged into engagement with the upper part of the post to locate the unit 10.

In a further modified version of the invention, not shown, there is provided on the vehicle an inclined "magazine" containing a supply of fencing posts which are delivered successively to the unit 10 which is partly open at one side so that when a post has been driven and the unit is removed from the driven post, the next post is automatically delivered to the unit and is held by it ready for driving. In the arrangements described above, post driving is normally a two man operation, one man driving the vehicle and another man locating the posts. With the "magazine" arrangement described above, however, the operation may be controlled entirely by one man driving the vehicle.

Claims (10)

1. Post driving apparatus comprising an elongate guide having means for pivotally connecting one end of the guide to a support located above the ground so that, in use, the guide may be suspended from the support and extend downwardly therefrom with the lower end of the guide spaced above the ground, means on at least the lower end of the guide for locating the lower end of the guide in relation to the upper end of a post to be driven, a weight movable up and down on the guide, and means for effecting said up and down movement of the weight on the guide.

2. Post driving apparatus according to claim 1, wherein the support is movable up and down so that the guide may be lowered into engagement with the top of the post and, if required, moved downwardly with the post as the post is driven into the ground.

3. Post driving apparatus according to claim 1 or claim 2, wherein the guide is provided with a lateral opening or slot so that it may be swung sideways to surround the upper part of the post.

4. Post driving apparatus according to any of claims 1 to 3, wherein the guide is pivotally suspended on the free end of a swinging arm for mounting on a vehicle.

5. Post driving apparatus according to any of claims 1 to 4, wherein the guide comprises a frame, open at least at the lower end thereof, within which frame the weight is movable up and down.

6. Post driving apparatus according to claim 5, wherein the weight is suspended on a flexible ele ment and power means are provided for hoisting the weight upwardly on the flexible element and allowing it to fall rapidly to impact on the upper end of a post located within the lower end of the suspended guide frame.

7. Post driving apparatus according to claim 6, wherein the power means comprise an hydraulic ram connected through a linkage to the flexible element so that upon extension of the ram the weight is hoisted upwardly by the flexible element and upon contraction of the ram the weight falls downwardly.

8. Post driving apparatus according to claim 7, wherein the linkage comprises a pivoted lever to one end of which the ram is connected and the opposite end of which is connected to the flexible element.

9. Post driving apparatus according to claim 8, wherein the ram is connected to the lever at a closer distance from the pivotthereof than is the flexible element.

10. Post driving apparatus substantially as hereinbefore described with reference to the accompanying drawings.