GB1566259A - Post drivers - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO POST DRIVERS (71) I, ALAN RAVEN EDWARDS, of Atheralls Farm, Fletching, Uckfield, Sussex, TN22 3TD, a British Subject, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a post driver for driving in wooden posts or stakes.

At the present time, farmers and fencing contractors requiring to drive in posts or stakes have to make use of either hand tools, such as metal sledge-hammers, wooden mallets, or tubular hand-drivers, or of some form of mechanical device.

The mechanical devices available mostly operate on the same principle as a pile-driver, a heavy weight mounted in some kind of frame carried by a tractor being raised either hydraulically or mechanically by means of wires or chains powered by the tractor, and then allowed to drop from a height onto the top of the post which is to be driven.

While such mechanical devices have advantages over hand tools, they have many disadvantages. They are very cumbersome and impossible to use in some circumstances.

Since each such device is mounted on a tractor, the tractor itself must be positioned accurately and exactly at the spot where it is desired to drive in the post. This is not possible in narrow or awkward places, for example, where the ground is steep or undulating, on banks, or in wet and boggy ground. Moreover, many of these mechanical devices require two operators, one to operate the machine itself and one to position and steady the post, and the operator must manipulate a control lever or valve at every stroke of the weight. The whole device, together with the tractor, has to be moved and repositioned for every individual post to be driven. Finally, the mechanical devices are expensive and they cannot, of course, be used for any other purpose than post driving.

It is an object of the present invention to provide a post driver which can be manually held and does not require to be mounted on a tractor and which does not therefore suffer from the disadvantages of the previously known tractor-mounted mechanical devices.

According to the invention, a post driver comprises a pneumatic percussion tool com- prising a tubular housing in which a pneumatically driven hammer is arranged to reciprocate axially, and an outer casing surrounding said tubular housing and forming a manually-holdable tubular guide member, said outer casing having an open-ended portion extending beyond the end of said tubular housing and adapted to be placed over the top of a post to be driven, and said hammer having a head extending into said portion.

While any sort of pneumatically driven hammer can be used, conveniently the hammer can be produced from a standard pneumatic earth rammer by replacing the rammer head adapted to operate within the tubular guide member to drive in the post.

The pneumatic hammer can be connected in the way usual with earth rammers by a flexible hose to a compressor mounted on and driven by a tractor, or to an engine-driven compressor mounted on a trailer. It is thus not necessary to park the tractor exactly at the spot where the post is to be driven but the tractor can be parked at any convenient spot by an unskilled driver and, depending on the length of flexible hose available, a number of posts can be driven in where required.without any necessity for moving the tractor. Operation of the pneumatic hammer is effected by operation of a control means governing the compressed air supply to the hammer and may conveniently be carried by a handle mounted on the exterior of the guide member.Preferably, the handle carrying the control means is in the form of a pipe through which compressed air is fed to the hammer in use, in which case the control means can conveniently be in the form of a twist grip on the pipe operating a control valve for the air supply.

With the pneumatic hammer of the present invention, continuous blows of the hammer at up to 750 blows per minute are possible.

While the pneumatic hammer of the present invention is not itself particularly expensive, the compressor is, of course, a more expensive item. However, most farmers and contractors will already possess a compressor for operating the many pneumatic tools now available, such as drills, spades, hedge-cutters and the like, and if a compressor has to be specially purchased for post driving, it can subsequently be put to a variety of other uses.

As previously stated, the pneumatic hammer can conveniently be produced by modifying a pneumatic earth rammer of known type and in this case it is, of course, easily possible to reconvert the device back to its original use for earth ramming.

While, when only a few posts have to be driven, the post driver of the invention can be held and carried manually from post to post, it has been found that when a large number of posts has to be driven involving, for example, a full day's work, manual holding and carrying of the driver becomes very tiring, and for such use, it is desirable to support the driver from a movable gantry, which can conveniently be carried by a tractor or other vehicle, in such a manner that limited vertical and lateral movement of the driver can be effected to enable the driver to be placed over a post to be driven without any necessity for exact positioning of the gantry.

One embodiment of the invention will now be further described with reference to the drawing, which is a schematic side view of the post driver and support means therefor.

Referring to the drawing, the post driver comprises an outer casing in the form of a tubular guide member 10, the lower end of which is open and adapted to be fitted over the top of a post 11 which is to be driven. The guide member 10 conveniently consists of a steel tube having a diameter of 6 or 7 inches.

Within the upper part of the guide member 10 there is rigidly fixed by means of spacers 12 and bolts 13, the non-moving barrel 14 of a conventional pneumatically-operated earth rammer, the guide member 10 being mounted below and clear of the exhaust 15 of the rammer and extending some 15 inches below the lower end of the barrel 14. Instead of the rammer head, there is fitted to the plunger of the barrel a hammer head 16. The normal compressed air feed pipe to the rammer barrel is removed and replaced by a compressed air pipe 17 which is of U-shape and extends downwardly parallel to the guide member 10 on either side thereof and terminates, at each side approximately opposite the lower end of the guide member 10 to which it is connected by upper clamps 18 and lower clamps 19. The two sides of the pipe 17 form the handles of the device.The flow of compressed air through the pipe 17 to operate the hydraulic hammer is controlled by a control lever 20 attached to the pipe 17 at the part thereof forming one of the handles, and itself operated by a twist grip formed by a pipe 21 axially surrounding the part of the pipe 17 forming the handle and being rotatable with respect to the pipe between open and closed positions of the lever 20. The twist grip can readily be operated by a person holding the two handles of the device.

Compressed air is fed to the barrel 14 from a compressor (not shown) through a flexible hose 22 connected to the lower end of the part of the pipe 17 forming the handle carrying the control lever 20.

When a large number of posts are to be driven, the post driver may, as shown, be suspended from a movable gantry. For this purpose, the upper end of the driver is attached to the lower end of a strong helical spring 24 suspended from one end of a gantry arm 25, pivoting at 29 about the top of a vertical member 27 which itself is arranged to rotate about its axis in a sleeve 27 which can be attached to a tractor or other vehicle, by arms 28. The weight of the post driver is balanced by a counterweight 26 located beyond the pivot point 29. The flexible hose can, as shown, be taken to the compressor via the gantry.

The arms 28 are hinged at their junction points 30 with the tractor and, by means of a ram 31, attached to the upper arm at 32 and to the tractor at 33, the two arms can be made to rotate with respect to the tractor as indicated by the arrow 34, so as to position the post driver accurately where required. The ram may also be operated by compressed air, or by hydraulic power if the tractor is so equipped.

In operation, the post to be driven is placed in the desired position, the lower end of the guide member 10 of the post driver is placed over the top of the post, the operator either holding the driver by the handles formed by the pipe 17, or its weight being supported on the gantry, if one is used. On depressing the lever 20 by means of the twist grip 21, com pressed air is fed to the barrel 14 from a com pressor (not shown) through the flexible hose 22, and the hammer head 16 is recipro cated within the guide member 10 to drive in the post to the required depth, the operator manually steadying and guiding the post so that it is driven in vertically. It will be seen that the post driver of the invention can easily be operated by one man who can both operate the lever 21 and guide the post during its driving in.

WHAT I CLAIM IS: 1. A post driver comprising a pneumatic percussion tool comprising a tubular housing in which a pneumatically driven hammer is arranged to reciprocate axially, and an outer casing surrounding said tubular housing and forming a manually-holdable tubular guide member, said outer casing having an openended portion extending beyond the end of said tubular housing and adapted to be placed over the top of a post to be driven, and said hammer having a head extending into said portion.

2. A post driver as claimed in Claim 1, wherein said tubular guide member is provided with handles, one of which is formed by a pipe through which compressed air is supplied in use to operate said hammer and which is provided with control means for the air supply.

3. A post driver as claimed in any one of the preceding Claims, wherein said control means is a twist grip on said pipe operating a valve controlling the flow of air through said pipe.

4. A post driver as claimed in any one of the preceding Claims adapted to be suspended for limited lateral and vertical movement from a gantry mounted on a tractor or other vehicle.

5. A post driver as claimed in Claim 4, wherein means are provided in the form of a helical spring for suspending the driver from said gantry.

6. A post driver substantially as hereinbefore described with reference to and as shown in the drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. that it is driven in vertically. It will be seen that the post driver of the invention can easily be operated by one man who can both operate the lever 21 and guide the post during its driving in. WHAT I CLAIM IS:

1. A post driver comprising a pneumatic percussion tool comprising a tubular housing in which a pneumatically driven hammer is arranged to reciprocate axially, and an outer casing surrounding said tubular housing and forming a manually-holdable tubular guide member, said outer casing having an openended portion extending beyond the end of said tubular housing and adapted to be placed over the top of a post to be driven, and said hammer having a head extending into said portion.

2. A post driver as claimed in Claim 1, wherein said tubular guide member is provided with handles, one of which is formed by a pipe through which compressed air is supplied in use to operate said hammer and which is provided with control means for the air supply.

3. A post driver as claimed in any one of the preceding Claims, wherein said control means is a twist grip on said pipe operating a valve controlling the flow of air through said pipe.

4. A post driver as claimed in any one of the preceding Claims adapted to be suspended for limited lateral and vertical movement from a gantry mounted on a tractor or other vehicle.

5. A post driver as claimed in Claim 4, wherein means are provided in the form of a helical spring for suspending the driver from said gantry.

6. A post driver substantially as hereinbefore described with reference to and as shown in the drawing.