GB2359581A

GB2359581A - Post driving apparatus

Info

Publication number: GB2359581A
Application number: GB0004379A
Authority: GB
Inventors: Miftach Taylor
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-02-25
Filing date: 2000-02-25
Publication date: 2001-08-29
Also published as: GB0004379D0

Abstract

A post driving apparatus, adapted to be readily portable comprises a sleeve adapted to grip a post to be driven, and a tube 1 coaxial with the sleeve, said tube having a weight 2 movable axially of the tube 1, a line 6 for lifting the weight, thereby compressing a spring 8. On release of the line 6, the weight 2 will fall and impact the top of the post, directly or indirectly (via. A dolly not shown), the force of the impact being increased by the expansive force of the spring 8.

Description

2359581 1 POST DRIVING APPARATUS The present invention relates to post

driving apparatus. More specifically, it relates to post driving apparatus for driving posts, such as fence posts, into the ground, and which may be readily portable and manually operated.

it is common to drive posts into the ground by means of mechanically operated systems, such as are used in piling for house foundations, etc. but these are of necessity large and complex in construction. Systems for small scale use which do not necessitate mechanically operated means are known. These generally comprise a sleeve adapted to fit over the post provided at the top end with a cap so as substantially to close the sleeve and the sleeve is moved up and forced downwards manually. Driving posts with such apparatus is often an arduous process, specially with hard ground, and means are known for reducing the physical effort involved. US-A-3856092 involves a weighting system, separate from the capped tube which is adapted to fit over the post. The weighting system is provided with stiff springs between the weight system and the capped tube, so that there is a resilient rebound effect, which reduces the force that has to be expended in lifting the apparatus. This has obvious disadvantages in tending to reduce the impact force of the cap.

There is still a need for a lightweight system easily portable, and permitting the driving of posts in a simple manner with the minimum expenditure of energy.

The present invention provides post-driving apparatus which comprises a tube, adapted to be a slidable fit within a sleeve for surrounding and gripping a fence-post or the like, a weight reciprocally movable axially of the tube, lifting means for the weight, being capable of raising the weight against the force of gravity when the tube and sleeve are vertically oriented, and a resilient member within the tube, compressible when the weight is lifted, and expandable when the weight is released whereby to apply a downwards force to the weight.

The invention will be more particularly described with reference to the accompanying Drawings, in which Figure 1 represents a longitudinal section through a tube forming part of the system; Figure 1 a is a view of the tube from above; Figure 2 is a view of a sleeve adapted to surround a post to be driven using the apparatus of Figure 1; and Figure 3 is a longitudinal sectional view, showing on an enlarged scale a bobbin used in one embodiment of the invention.

Referring now more particularly to the Drawings, a tube [1] hereinafter sometimes referred to as the impact tube, has within it a weight [2], adapted to be reciprocally moveable along the bore of the tube. The weight [21 is supported on a line [31 extending axially of the tube and over a pulley [41 journalled within a pulley block [51 at the top of the tube. The free end of the line [3] remote from the weight [21 can conveniently be provided with a number of grips [61 so that the weight [21 may conveniently raised manually. Between the weight [21 and the pulley block [51 there is located a spring means [81. Preferably handles [71 are fitted to the outside of the tube, so that it may be easily carried.

Figure 2 represents a sleeve [101 adapted to fit over a fence and provided at its upper end with an adapter section [111 of larger internal diameter than the tube [11, and sleeve [101, its diameter being such as to form a slidable fit with the exterior lower end of tube [ 11.

3 In order to engage a post to be driven, two or more triangular wedges [12, 131 are provided, being moveable within respective longitudinal slots [ 141 in the walls of the sleeve. The lower ends [ 151 of these wedges [ 131 are pivoted at the walls of the sleeve. Their upper ends [161 are urged into the interior of the sleeve, when the sleeve is not placed over a post by means of elastic means, such as rubber rings or springs [171, encircling the sleeve. When the sleeve is placed over a post to be driven, and moved longitudinally along the post, the upper ends of the wedges [131 are forced radially outwards, and project out of the slots so that the sleeve may engage the post. The tube 111 is then placed within the adapter member [ 11].

Operation of the system according to the invention is quite simple. A downward pull on the free end of the line causes the weight [21 to be lifted compressing the spring [61. At an appropriate height, the free end of the line [31 can be released, and the spring forces the weight [21 downwards so as to impact upon the top of the post.

In one preferred embodiment of the invention, illustrated in Figures 2 and 3, the impact of the weight [21 is not directly transmitted to the post, but is transmitted from the weight to the post by means of a bobbin [201 shown in Figures 2 and 3. This bobbin has a cylindrical upper section [211, a cylindrical lower section [22] and an intermediate section [23]. The upper, lower and intermediate sections are generally cylindrical, the diameter of the intermediate section [231 being less than that of the upper and lower sections [211 and [22]. This bobbin is retained by a section [241 at the top of the sleeve [l 01, this section [241 being circular and coaxial with the sleeve and having an internal diameter less than that of the upper and lower sections of the sleeve but greater than the diameter of the intermediate section [231 of the bobbin, in a manually portable version of the post driver, this clearance may be about 2 mm. but the exact clearance is of no significance except insofar as it should be sufficient to allow free movement of the bobbin. Section [241 is of shorter 4 axial dimensions than the intermediate section of the bobbin so that the bobbin [201 is moveable axially within the section [241. When a post is inserted into the sleeve [ 101, it pushes the bobbin [201 until the upper face of its lower section [221 contacts the lower face of section [241. Then when the weight [21 impacts the upper face of bobbin [201, the force of the impact is transmitted to the post by the bobbin.

In an alternative embodiment, the bobbin [201 may be dispensed with, and the weight [21 will have a lower section which has a reduced diameter, adapted to pass through section [241 and impact directly on the top of the post.

The tube and sleeve are advantageously constructed of a rigid abrasionresistant plastics material, such as acrylonitrile-butadienestyrene (ABS) or of material of comparable characteristics, which may if desired be reinforced with suitable fibres or fillers. The advantage of using a plastics material rather than a metal is that it considerably reduces the weight and makes it more readily more portable manually. The tube and sleeve may, however, be constructed of metal or a suitable alloy, e.g. duralumin. The metal may, if desired, be provided with a corrosion proofed surface, e.g. by anodizing.

An advantage of the invention is that the impact force is not transmitted from the post to the post driver, The spring loaded wedges on the post sleeve allow movement and a dampening effect, which cushions the shock when the post is impacted. The bobbin also stops impact vibration being transmitted to the main machine. The tube and sleeve act as guides for the weight and post without the forces of impact being transmitted to them.

A prototype machine constructed for ready portability, has an impact tube [11 length of 5 ft (1 52.4cm), an internal dimension of 5 ins (1 2.70cm), an impact tube external dimension of 5.625 ins (1 4.29cm) and an impact tube weight of 11 lbs (5 kg). The total weight of the machine is 35 lbs (15.9 kg). The exact dimensions are not essential to the invention, and may be varied as desired.

The figures above show that the tubular guide weighs less than 1/3 of the total machine weight.

The post driving machine described and shown in Drawings is a machine which is operated manually i.e. by pulling and letting go the line. One man can easily carry and operate this machine.

If it is desired to increase the power to be exerted on the top of a post to be driven, this can be done by providing a tube [11 of greater length, increasing the strength of the spring [81, or by increasing the mass of the weight [21.

This machine could easily be manufactured as a two man machine or a power operated machine.

A two man machine could be at least twice as heavy as existing machine i. e. 70 Ibs (31.8 kg). It could have two pulleys and two ropes allowing potential to double the impact of the weight. The mass of the weight [21 could be increased. The compression rate of spring means [81 could be increased. The tube diameter and length of the tube could be increased. Tube internal diameters could vary from 2" to 1W (6.1 to 30.5 cm). The mass of the weights could vary between 2 lb and 55 Ibs (0.9 and 25.0 kg). The force exerted by the fully compressed spring could possibly be increased as far as 300 lb (136.2 kg). The tube length could be between 2 ft and 10 ft (0.61 and 3.05m).

These parameters should cover most practical applications for the post driving machine and hopefully any other use the machine may be put to. Apparatus 6 having the same weight and dimensions parameters as listed previously could also be used for one or two man operation.

A spike can be used to punch a pilot hole into hard ground. The dimensions of this spike can vary depending upon the size of post used, and could make boring a hole with an auger unnecessary.

The use of the apparatus according to the invention may be carried out safely since all moving parts are contained within the tube so that the risk of injury to an operator is minimized.

The apparatus has been described with reference to manual operation. It could, however, if desired, be mechanized.

The pulley carrying the rope may be connected a drive motor which would rotate the pulley. Rotation of the pulley would wind up the rope hence pulling the weight up the tube against the compression of the spring. At a certain point i.e. at the end of stroke, the motor would either switch into reverse or be clutch operated to release the pulley and hence drop the weight.

A light-weight slow running motor say no more than 125 rpm by air, electricity or other power means. Most sites would not have services provided to provide a convenient power source so portable generators, compressors, etc may be employed.

Another way of pulley the weight up the tube would be to use a double acting air cylinder. The air cylinder would be pressurised to pull on the rope which would lift the weight. The air supply would then be switched to the other side of the cylinder, and the weight would fall.

7 A convenient size of air cylinder has a 12" (30mm) stroke. The pulley will have a 4:1 or 5:1 gearing so that one stroke of such an air cylinder would lift 4 or 5 times that height.

According to another possible, although less convenient, embodiment the sleeve and the tube may be combined into a single unit. This, however, would be of greater length and less easily manipulated.

8

Claims

1. Post-driving apparatus which comprises a tube, adapted to be a slidable fit within a sleeve for surrounding and gripping a fence-post or the like, a weight reciprocally movable axially of the tube, lifting means for the weight, being capable of raising the weight against the force of gravity when the tube and sleeve are vertically oriented, and a resilient member within the tube, compressible when the weight is lifted, and expandable when the weight 'IS released whereby to apply a downwards force to the weight.

2. Post-driving apparatus as claimed in Claim 1 wherein the sleeve comprises two or more triangular wedges movable in longitudinal slots in the walls of the sleeve, one corner of each triangle being pivoted at the wall of the sleeve at the ends of respective slots distant from the upper end of the sleeve, and provided at the ends of the slots nearest the upper end of the sleeve with means urging the wedges into the sleeve whereby to grip a post.

3. Post-driving apparatus as claimed in Claim 1 or 2 wherein the weight is dimensioned so as to impact directly on the top of a fence post.

4. Postdriving apparatus as claimed in Claim 1 or 2 wherein the sleeve has at its upper end a bobbin for transmitting the impact of the weight to a post being driven.

5. Post-driving apparatus as claimed in Claim 4 wherein the bobbin has cylindrical and coaxial upper, lower and intermediate sections, the diameter of the intermediate section being less than that of the upper and lower sections.

6. Post-driving apparatus as claimed in any of Claims 1 to 5 wherein the lifting means comprise a flexible line, fastened to the top of the weight, and 9 extending axially of the tube over a pulley journalled at the top of the tube in a pulley block, and extending down the outside of the tube.

7. Post-driving apparatus as claimed in any one of Claims 1 to 6 wherein the lifting means comprise a flexible line, fastened to the top of the weight, and extending axially of the tube over a pulley journalled at the top of the tube in a pulley block, said pulley block being operated by a suitable power source.

8. Post-driving apparatus as claimed in any of Claims 1 to 7 wherein the tube is provided with handles for carrying the apparatus, and supporting the apparatus when in operation.