EP1549804A2

EP1549804A2 - Post piling apparatus

Info

Publication number: EP1549804A2
Application number: EP03743931A
Authority: EP
Inventors: Lewis Edney
Original assignee: Edney Lewis
Current assignee: DRIVEAPOST LIMITED
Priority date: 2002-03-09
Filing date: 2003-03-10
Publication date: 2005-07-06
Also published as: GB0205617D0; AU2003209503A1; WO2003076728A3; WO2003076728A2

Abstract

The invention provides a post piling apparatus comprising: an alignment means operably connected to a prime mover by a support arm; and a driving device suspended from said alignment means, the driving device including means for driving a post or like article into the ground. The support arm may be operably connected to and powered by the prime mover. In an alternative embodiment a pile driver is arranged to hold and guide a pile whilst it is being struck with a hammer mass via an impact plate. The driver is adapted to receive one of a number of removable profile and impact plates. Profile and impact plates are adapted to receive square, semi-circular, corrugated and sheet piles so that they are held steady whilst being driven and the impact force is transmitted evenly to the ground penetrating area of the pile. Profile plates and impact plates are reversible so as to allow for setting contiguous runs of sheet piles, for example, from right to left or left to right. A cutout section is provided in the part of the pile driver that supports the pile guide so as to allow for adjacent, contiguous piles to be driven to the same depth.

Description

POST PILING APPARATUS

Field of the Invention

The present invention relates to a post piling apparatus and more particularly to an apparatus for driving fence posts into the ground. In an alternative embodiment the invention relates to a pile driving apparatus for driving piles into the ground.

Background to the Invention

To erect a fence it is normal to attach fence panels, beams or fence wire between posts driven into the ground. Most commonly, each post is driven into the ground manually using a hammer. Where a long run of fence is required, this is a slow and laborious procedure.

A reference made to a post in the following description is not intended to be limiting in that the invention is adapted for use with a variety of ground penetrating items including hole formers for telegraph poles, large earthing rods, drainage devices and the like. Similarly it will be appreciated, with particular reference to the second aspect of the invention is intended to encompass a variety of piles, some of which may have non-uniform cross-sections and/or are arranged to interlock, one with another.

A known solution to the problem of driving a post or a pile into the ground is to attach a post or pile driving mechanism to a conventional three-point linkage of a tractor. Hydraulic power can be provided via the hydraulic power take-off coupling, which is conventionally provided adjacent the three-point linkage. In these conventional arrangements, it may be difficult to manoeuvre the tractor and therefore the post or pile-driving apparatus into restricted spaces; or there may be a risk of damaging a crop, for example, if a tractor needs to be manoeuvred into a restricted position in a field. Devices for attaching to the front loader mechanism of a tractor usually comprise a pair of hydraulically operated arms which move either side of a tractor engine and are conventionally attached to a loading device such as a bucket or tines of a forklift.

Prior Art

Although front loader mechanisms have the advantage of being more easily monitored by an operator or driver of the tractor, it is a well-appreciated problem that it is difficult to consistently and vertically align posts before they are struck into the ground. There are available many complex linkage mechanisms to ensure that posts are maintained vertical with respect to the prime mover or tractor, however these can require additional personnel in order to align and operate them and of course they entail more expense. In addition to this, existing post and pile drivers do not account for sloping ground or access to awkward areas, such as boggy or soft ground, particularly at the edge of ditches, gulleys or on riverbanks.

Other mechanisms have been devised, such for example that shown in United Kingdom Patent Application GB-A-2 336 868 (Stanley Roberts), which discloses the use of a vertically hanging chain that is aligned to a pilot hole forming spike. Unfortunately, this arrangement only ensures alignment of the spike, and consequently the apparatus, in one plane only. Its use still entails that an operator has to check alignment in an orthogonal plane to ensure that the apparatus is correctly aligned.

Existing techniques for driving sheet piles have been relatively unsophisticated and have sometimes entailed simply driving the sheet pile into the ground with a bucket of a tractor or vibrating them with pneumatic or hydraulic vibrator.

It is an object of the present invention to provide an improved post piling apparatus particularly for use with fence posts. It is a further object of the present Invention to provide a post piling apparatus, which may be aligned from a single vantage point and irrespective of the relative position or orientation of the prime mover thereto.

It is another object of the present invention to provide a driving device, which improves hammering efficiency and is easy to couple to and uncouple from a prime mover.

It is a yet further object to provide an apparatus for driving piles, particularly those that have a non-uniform cross section, into the ground; the pile driving apparatus having at least some of the aforementioned features.

Summary of the Invention

Accordingly, the present invention provides in its first aspect a post piling apparatus of the type suitable for driving fence posts into the ground. The apparatus being attachable to a prime mover, for example a tractor, and comprises:

an alignment means (gantry) operably connected to a prime mover by a support arm; and

a driving device suspended from said alignment means, the driving device including means for driving a post or like article into the ground.

Preferably, the alignment means or gantry is supported by a strop, a universal joint, a chain or other similar means so that it can be suspended from the prime mover.

Conveniently, the support arm is operably connected to, and powered by, the prime mover. Alternatively, the alignment means comprises a cable or wire hawser. Cable retraction may be by way of a motor and/or pulley arrangement.

The fact that the apparatus is slung or suspended ensures that the apparatus naturally assumes a plumb position irrespective of the position or pitched angle of the prime mover. Therefore, regardless of the angle of incline of slope on which the prime mover (tractor) may be located, the full vertical component of any impact or driving force is always available as the impact mass falls vertically.

A further advantage is that no adjustment of the apparatus or alignment means is required to obtain correct orientation of the post or pile in the second major plane. The fact that an impact mass (hammer) is suspended effectively at a point, and is therefore free to assume a plumb orientation, removes the need for this second stabiliser or alignment mechanism. The practical effect is that the apparatus is simpler and cheaper to manufacture and simpler to operate.

The support arm of the prime mover may comprise any element of the prime mover or attachments therefor designed to lift or manoeuvre other articles.

According to a second aspect of the present invention, there is provided a post piling apparatus suitable for suspension from a support arm in operable attachment to a prime mover, the apparatus comprising a means for driving a post or like article into the ground, in which:

a hammer mass is confined within a pair of guide rails held in parallel configuration at an impact end and at a lifting mechanism end, said impact end including means for retaining a post in relation thereto and said lifting mechanism end supporting a lifting mechanism operably coupled to said hammer mass.

Conveniently the post piling apparatus when suspended from a support arm of a prime mover, in use, facilitates the utilisation of the full hammer mass travel distance, (as defined by an available hammer travel distance in the guide rails), for each impact to a post or like article to be driven into the ground.

In traditional arrangements, the post is loaded into the post piling apparatus and occupies a length, or substantial proportion thereof, of the hammer travel distance. Thus, initial impacts were significantly less effective than latter impacts, where a greater length of travel distance is available. The present invention however, ensures that all, or substantially all, of the hammer travel distance, is available for each hammer blow, by providing a facility to lower a gantry towards the post or pile to be driven, after successive hammer impacts. Therefore hammering times may be reduced significantly. Practically this may be achieved by providing a motor or winch facility or other means for vertically displacing the apparatus with respect to the post or pile to be driven.

Advantageously raising and lowering the apparatus may be achieved by a mechanism, which suspends the apparatus from a prime mover support arm; by means of a chain, cable or wire hawser; or a winch mounted on the prime mover. Alternatively a crane can lower the apparatus as the post or pile is being driven.

The post piling apparatus according to the invention increases the ease and speed with which the hammer mass may be attached to or detached from a prime mover; there being a mechanical attachment and hydraulic hoses for powering the pile driving apparatus.

Thus, the driving device may be fitted to any prime mover having a moveable support arm or may be adapted for such use. Prime movers considered include: tractors, particularly agricultural tractors, but may include tractors simply provided with a loader mechanism or bale spike; fork lift trucks; 360° excavators; wheeled diggers having either front or rear lifting means, particularly such prime movers produced by JCB (trade mark); telescopic handlers; and HIAB (trade mark) type cranes mounted on commercial vehicles, for example, between a driver cabin and a load bed.

The term "hammer mass" as used herein is directed towards any mass, the impulse of which is used to impart a force under gravity to a target.

The apparatus preferably includes a pile-gripping device, with a post retaining plate, adapted to be secured to the apparatus at, about or around the lower part of the gantry. The plate has a throughbody bore adapted to receive a post or pile and includes a locking arrangement operable to retain the post within the bore.

The gripping device may be a locking pin, catch or sprung member. However, in one preferred embodiment, hydraulic locking jaws have been found to be particularly effective, as when gripping the pile, the jaws prevent twisting of the pile which a liable to flexing about its longitudinal axis. An hydraulic feed for the locking jaws is preferably also taken from a valve arrangement (known as the third service) that powers the hammer mass lifting mechanism.

When the apparatus, with a post or pile located, has been positioned, so that the ground-penetrating end of the post is in the required position, touching the ground, the gripping device may be released so as to allow the post or pile to be driven, whilst still providing the post or pile with sufficient lateral support in order to keep it upright. The upper end of the post or pile is struck and the apparatus is repositioned (lowered) to expose a further striking length of pile or post above the retaining plate on the pile-gripping device.

Automatic sensing means may be provided in order to detect the amount of downward displacement of the pile or post after each impact, and adjust the apparatus accordingly. The lowering means may be operated under control of an infrared distance detector in order to achieve this.

Conveniently, the throughbody bore of the retaining plate may be shaped to accommodate a particular post dimension or shape and, accordingly, a variety of different plates can be provided for use with the apparatus. This is of particular relevance for square and half-round posts, to which fence panels or slats are secured. It is essential for panel fencing that flat surfaces of posts supporting the fence, all face the same way, for securing the fence panels.

Preferably the retaining plate is held in a housing, which is disposed in a post or pile- gripping device supported by a gantry. The gantry is defined by guide rails, which confine the hammer mass, ensuring it is only able to move substantially parallel to the guide rails (thereby preventing the hammer mass from swinging uncontrollably) and ensuring that the hammer mass impacts the post or pile substantially at a central position and squarely. This is due to the unique ability of the apparatus, in that it ensures the hammer mass and top and bottom of the post or pile, are all substantially colinear. The practical result is that the post or pile will always driven vertically into the ground, irrespective of the nature of the surface of the ground, because the resultant force applied is provided from a vertically falling hammer mass along the vertical axis of the post or pile. The process is enhanced by the fact that a pile-gripping device supports the post or pile at a position intermediate its top and bottom. This lateral support further ensures the post or pile does not topple or tilt during the initial impacts.

Automatic means may be provided to relax the grip of the pile-gripping device prior to impact so as to allow the post or pile to be driven freely.

The post or pile-gripping device is supported in the gantry in a displaceable housing. The displaceable post or pile gripping device enables the orientation of posts or piles to be reversed so that runs of interlocking piles, for example, may be installed in either direction (sense) left to right or right to left. This will be appreciated with reference to the detailed description below.

The shaped bore of the retaining plate may firstly be used to align the post and secondly may prevent twisting of the post or pile from occurring during the hammering operation.

When a post strikes a stone, for example, twisting often occurs and this twisting can be corrected by a counter-twist force applied during subsequent hammer strikes. To this end, a user may hold a manoeuvring rail to correct any twists. The manoeuvring rail is therefore suitably dimensioned and arranged so as to enable the user to impart sufficient torque to counter balance any twisting of the post or pile.

One of the particular advantages of the present invention, over existing post drivers, is that the post piling apparatus and/or driving device is essentially self-contained and merely requires a point from which it is to be suspended and a hydraulic (or similar power) feed for lifting the hammer mass and actuating any locking jaw. This obviates the requirement for matched or complimentary supporting arms or non- integrated mechanisms for lifting the hammer mass, for example. Moreover it provides a user with an integrated pile driver that is easy to operate.

According to a further aspect of the invention there is provided a pile driving apparatus including: a gantry, which is capable of being raised and lowered with respect to the ground and which is adapted to be slung from a suspension point on a prime mover so that in use it is plumb; the gantry supporting a hammer mass, which in use applies a force to a pile; an intermediate support means supports the pile at a point intermediate the top of the pile and the ground; and a means for raising the mass so that it may be released to achieve a hammering action.

An impact shoe may be provided and ideally has a profile adapted to receive a pile and to distribute the impact force evenly across the pile.

Preferably the intermediate support means also provides a releasable locking mechanism that releases the post or pile momentarily prior to impact of the hammer mass. A manoeuvring rail, in the form of a grip or handle, is ideally also provided. This may be of a rigid nature and offers the user or operator the ability to locate, twist and orient the apparatus so that it is positioned correctly with respect to a post or pile to be driven. The manoeuvring rail may also provide a support for controls and/or a hammer release and retract mechanism.

Advantageously the releasable locking mechanism supported by, or located in, the intermediate support means, is provided with a displaceable mechanism to enable it to reorient the post or pile in a particular position with respect the ground (or another post or pile). Ideally this arrangement includes a housing rotatable on a shaft, the housing being capable of being secured in one of two orientations. The shaft is ideally perpendicular to the guide rails and supported therebetween. An hydraulic feed can be used to drive the housing, ideally by flipping it, between each of its orientations.

In a particularly preferred embodiment a portion of the intermediate support housing is cut away or removed in order to permit piles to be driven, so that adjacent piles do not impinge one upon another and so as to permit runs of piles to be driven to substantially the same height.

The manoeuvring rail may be located away from and around the gantry, for example by way of rigid spokes, and ideally is fitted with a safety release so that a user has to disengage (or engage) one or more safety switches, simultaneously with one hand (for example by holding the manoeuvring rail), whilst the second hand is employed (for example on a trigger) to release the mass to impact the post or pile. The combined effect of these safety switches is to provide a safety feature that ensures that neither of the user's hands is ever in a location where they could be impacted by the mass.

The manoeuvring rail may be displaceable vertically, with respect to the gantry, so as to allow an operator standing on the edge of a ditch or bank to lower the gantry to a position where it may impact the pile being driven, whilst steadying a point higher on the gantry than before. Retractable spring or pinch bolts, for example disposed on the manoeuvring rail, may be retracted and re-engaged with holes, which may be disposed along the length of the gantry, to facilitate this.

Alternatively control and actuation triggers can be disposed on the gantry, but are operable only when depressed simultaneously (thereby providing the important safety feature). Control signals may be transmitted to actuators, motors and pumps by way of (short range) radio frequency (RF) signals or via electrical or optical wires or cables. In the case of wire or cable connections, these may pass inside hollow sections of the gantry guide rails for added safety. Spool retractors may be provided to retract the cables or wires in order to accommodate any relative movement between the manoeuvring rail and gantry.

The manoeuvring rail is ideally of sufficient size as to accommodate posts and piles of various shapes and sizes that may have already been driven into the ground. However, it has been found that a manoeuvring rail of substantially circular shape and having portions of the circumference cut out at opposite sides, is ideal for certain types of piles which need to engage one with another. This is because the manoeuvring rail enables the piles to be driven into the ground with substantially the same amount of pile exposed above the ground, without the risk of any of the exposed piles (already driven), impinging on the manoeuvring rail. In situations where runs of interlocking piles are required, this aspect of the manoeuvring rail facilitates piling of adjacent piles so that piles may be driven to a depth where substantially the same amount of each pile is exposed above ground level.

Ideally there is provided a plurality of removable impact shoes and intermediate support means, each being suitably profiled for different shaped piles. Impact shoes and intermediate support means ideally have left and right hand versions (or may have both) so as to permit run of piles to be reversed. The intermediate support means and impact shoes are removable and so can be changed according to the shape of post or pile to be driven. Ideally the support means and impact shoe are adapted to be housed in rigid support frames. Similarly removable post and pile gripping devices may be provided.

An hydraulic dump valve is advantageously provided which is capable of rapid opening to allow maximum rate of exhaust of hydraulic fluid, whilst presenting minimum impedance to said flow. The dump valve exhausts hydraulic fluid to a reservoir at a rate sufficient to allow the hammer mass to free-fall.

Brief Description of the Drawings

Preferred embodiments of the present invention will now be described, by way of example only, and with reference to the Figures in which:

Figure 1 is a front elevation of a first embodiment of driving device;

Figures 2a and 2b are a front elevation and side elevation of a second embodiment of driving device, respectively;

Figures 3a and 3b are perspective and side elevation views of alternative embodiments, showing respectively: a hammer mass supported by two guide rails (corresponds to Figures 2a); and one guide rail (corresponds to Figure 2b);

Figures 4a and 4b are top plan views of the lifting mechanism in positions corresponding to bottom of hammer travel distance and top of hammer travel distance, respectively;

Figure 5a is an underplan view of an alternative embodiment to that shown in Figure 3a, and shows part of the guide rail removed; Figure 5b is an overall view of a lower brace piece profiled to receive a pole retaining plate;

Figure 5c is an underplan view of the alternative embodiment shown in Figure 5a;

Figure 5d is a side elevation of a post support tube adapted to receive and locate a post within the lower brace piece;

Figure 5e is a side elevation of the embodiment shown in Figure 5c;

Figure 6 shows diagrammatically an overall exploded view of an alternative embodiment of a lower brace piece that is profiled to receive a non-uniform cross- section pile and shows a removable, reversible profile plate and lock mechanism;

Figure 7a is a perspective view of an impact shoe showing in exaggerated hidden form, a channel for receiving a pile having non-uniform cross section;

Figure 7b is an underplan view of Figure 7a;

Figure 8a is a perspective view of a pile locking or gripping device and shows mechanically actuated locking jaw sandwiching a non-uniform cross section pile;

Figure 8b is a plan view of the embodiment shown in Figure 8a showing the hydraulically actuated locking jaw closing on a pile having non-uniform cross section;

Figure 9a is an overall view showing guide rails and hydraulic ram for reversing the sense of the post or pile-gripping device;

Figure 9b is a side elevation showing the hydraulic ram and cam in different positions corresponding to a first sense (dotted) and a reversed sense (solid) of the gripping device;

Figures 10a, 10b and 10c are a front elevation, perspective and underplan views respectively of the top of the gantry and show suspension hook, guide rails, one hydraulic cylinder and pulleys;

Figure 11a is a part front elevational view of one embodiment showing the lower part of the gantry, the guide rails and the hammer mass;

Figure 11b is an overall view of one example of the hammer mass with guide fins;

Figure 11c is a part front elevation view showing the relationship between the guide rails and the gripping device;

Figure 12 is an hydraulic circuit suitable for use with the post and pile driving embodiments;

Figure 13 is an overall view of an hydraulic dump valve; and

Figure 14 is a plan view of the hydraulic dump valve showing hidden detail.

Detailed Description of Preferred Embodiments of the Invention

Referring generally to all the embodiments, typical dimensions of the post or piling apparatus are 2-3 m high, with an approximate width of between 0.5-1.0 m. The embodiment shown in Figure 1 is a first embodiment of pole or post driver 1 and comprises a hammer mass 2, which is confined within a pair of guide rails 4. Typically the hammer mass 2 may be formed from mild steel, cast or wrought iron and may weigh between 20-350 kilogrammes. However, it will be appreciated that the weight of the hammer mass 2 may be as large as is required in order to drive the particular post or pile. At a bottom impact end 5 of the driver 1 , pole or post P is secured with respect to guide rails 4 by a retaining plate 6 to position the pole P for impact by the hammer mass 2, in use.

Key components of the pile driver, such as the guide rails, cross pieces, and braces are fabricated from mild steel and are either welded or bolted together. This provides strength to the overall structure and is relatively cheap.

Guide rails 4 are held in parallel configuration at impact end 5 by a brace structure 7 to which a plate 6 is normally secured and at the other lifting end 9 by reinforcing brace members 10 which include an attachment linkage 12, by which the driver 1 may be attached to the support arm of a prime mover (not shown). The guide rails 4 and brace structures 7 and 10, drive means and pulleys are hereinafter collectively referred to as the gantry.

Lifting mechanism 15 comprises a pair of moveable linkage arms, each comprising a pivot arm 17 to which a lever arm 19 is rotatably attached about a pivot 20 at one end. Each lever arm carries a pulley wheel 21 at its other end. In use lever arm 19 is displaced, from a position in which it is substantially parallel to the guide rails 4, to an angularly disposed position (shown in dotted lines). This displacement of the lever arms 19 lifts the hammer mass 2, by a hydraulic ram 23 positioned between the pivot arm 17 and the lever arm 19. The mass 2 is lifted by cables 24 which are passed over pulley wheels 25 rotatably mounted to the brace 10 at the upper end 9 of the driver 1. The cables 24 are secured at one end to the hammer mass 2 and at the other end to the upper end brace 10 having been passed over the two pulley wheels 21 , 25. It will be seen that significant movement of the hammer mass 2 will be effected by nominal angular movement of the lever arms 19.

In use, the driver or gantry 1 is suspended from the support arm of, for example, the digging arm of a JCB (trade mark) by a chain (not shown), which is coupled to linkage point 12. The pole P to be hammered into the ground is positioned into the retaining plate 6, to which it is secured by a locking pin (not shown). The plate 6 is bolted, or otherwise secured to the brace structure 7, to ensure the pole P is maintained within the confines of the guide rails 4. The driver assembly is moved to the point where the pole P is to be erected and final adjustment may be made using a manoeuvring rail 26 to eliminate any pendulum effect and to conduct any minor adjustments. When the pole P is in the correct position and in contact with the ground, the locking pin is released. This may be done automatically or with a spring- loaded trigger.

An hydraulic feed is provided to actuate the hydraulic rams 23 which when extended move the lever arms 19 outwardly and cause the cables 24 to be taken up, thus lifting the mass 2. In an alternative embodiment one or more motors may be used to lift the hammer mass, for example by way of a pulley system, or the mass could be raised using chains. When hydraulic pressure is released or actively reversed, the hammer mass 2 is dropped to provide a full-length hammer impact force to the exposed end of the pole P protruding upwardly of the retaining plate 6. As the pole P is hammered into the ground, the prime mover supporting arm is lowered during the mass lifting procedure to again ensure that a striking length of the pole P remains exposed and thus the full travel of the hammer mass 2 is used to impart maximum impact to the pole P. Alternatively the prime mover may be held in a substantially constant position and the gantry is lowered. This action is repeated until the pole P is secured in the ground to whatever depth or exposed height is required.

Referring now to Figures 2a to 4b, and initially to Figures 2a and 2b, a second embodiment of pole driver 30 is shown substantially as before. Again, there is included a hammer mass 32 retained within parallel guide rails 34 (or about a single rail 34 as shown in Figure 2b). The rails are maintained in rigid configuration at the impact end 35 and the lifting mechanism end 39. Lower brace piece 37 is profiled as a substantially square cross-sectional tube (shown in Figure 5b), as shown in Figures 3a and 3b, adapted to receive a pole retaining plate 36 (shown in detail in Figure 5d) and pole to be driven. An example of a retaining plate suitable for retaining a pile of non-uniform cross section is shown in Figure 6 and is described in detail below.

Post support tube 36 is bolted to the lower brace piece 37. The pole P is retained within the post support tube 36 by a locking pin 120 mounted to the brace piece 37 for subsequent release before the hammering action commences. At the opposite end 39, a cross-member 40 is provided to support the lifting mechanism and to carry a first pair of pulley wheels 41 which share a common horizontal axle and a second pair of pulley wheels 42. The first pair of pulley wheels 41 are substantially vertically disposed and are positioned to receive the lifting cables 43 and translate the pulling direction laterally to the second pair of pulley wheels 42 on the cross-member 40.

Figures 10a, 10b and 10c are views of the upper part of a gantry, which is capable of being used with different embodiments of post and pile drivers. Details of pulleys 42 are shown to assist in the understanding of other Figures, particularly Figures 1 to 3. There is depicted only one hydraulic ram 47, which may be replaced with two rams in other embodiments, depending upon the type of pile or post to be driven and the weight of the hammer mass 32.

Lifting mechanism includes a member 45 for transforming linear movement, provided by a ram 47, to rotational movement about a centrally disposed vertical pivot 50. At each end of the member 45, a pulley wheel 52 is disposed and comprises the driving element for lifting the hammer mass 32. The member 45 also carries a linkage 55 to which a chain or cable may be attached for securing the driver 30 to the support arm of a prime mover.

Referring particularly to Figures 4a and 4b, in the position shown in Figure 4a, the mass 32 is disposed at the lower end of its travel and minimal tension is applied to the lifting cable 43. As hydraulic power is applied, the ram 47 extends causing the member 45 to rotate (clockwise from above) about its central vertical axis 50 (as shown in Figure 2a). As the member 45 rotates, the cable 43 is taken up by the distance generated between the member mounted pulley wheel 52 and the corresponding pulley wheel 42 fixed to the guide rail supporting cross-member 40. Eventually, when the mass 32 is raised to its maximum height, the position depicted in Figure 4b is reached.

As before, when hydraulic pressure is released or reversed the hammer mass 32 drops onto the exposed end of the pole to drive the pole P into the ground. As the mass drops, the rotating member 45 is returned to the position illustrated in Figure 4a.

The embodiments of the present invention provide a mechanically simple driving mechanism which is not specific to a given machine and is easily attachable to or detachable from the prime mover used. The post piling apparatus conveniently remains vertical at all times without any necessary adjustment. Full travel of the hammer mass is available by lowering the gantry. Also as the driver is suspended it is simple to manoeuvre it into previously inaccessible areas and use of the driver over hedges, existing fences, ditches and embankments is realisable. With relative ease the driver will accommodate and install most common sizes of post including square and round posts or half-round and quadrant posts.

To assist in the retention and orientation of the various types of post available, a variety of retaining post support tubes 6, 36 are provided. Each post support tube 6, 36 has a throughbody bore (shown in Figures 5c, 5d and 5e) which is profiled to correspond to the cross-section of the post, be they round (of various diameters), square or half-round. With the square and half-round posts, the retaining post support tube 6, 36 may prevent twisting of the pole P as it penetrates the ground. Where a twist occurs, for example, upon encountering a stone, the twist can be rectified by applying a counter-twist force to a manoeuvring rail 26.

The relative simplicity of the post piler ensures that it can be made at a fraction of the cost of existing driving mechanisms that are notoriously cumbersome and complex and due to their weight require sufficiently large machinery to act as a prime mover. Additionally, due to leverage problems with a heavy mechanism close work only can be facilitated. By contrast, a relatively long digging arm or HIAB (trade mark) type crane commonly used in commercial vehicles may be used to support the post or pile driving apparatus. In this way substantial reach can be obtained without risk of destabilising the prime mover and in some instances a run of fence posts may be erected without relocating the prime mover. It is feasible to erect up to six posts in a run without relocating a prime mover using the device of the present invention.

It will be appreciated by the skilled artisan that rubber block or the like may be installed on the impact ends of the guide rails 4, 34 or on the pole retaining post support tube 6, 36 so that should the hammer mass 2, 32 be dropped without a pole P in position, damage to the apparatus may be attenuated or eliminated.

Although particularly well adapted for use with posts it is understood that the invention is also suitable for use with piles. Further aspects of a particularly advantageous embodiment of the invention will now be described, with particular reference to Figures 5 to 14, which aspect is particularly well suited for driving piles, particularly piles having a non-uniform cross section (i.e. not square or circular) which piles are herein referred to as sheet piles.

A further embodiment of the invention is now described with general reference to Figures 1 to 4, but with particular reference to Figures 5 to 14. The third embodiment is adapted to drive posts and piles into the ground particularly whose cross section does not possess mirror symmetry or which are irregularly shaped. An example of one such pile is a sheet pile and is often used, for example, in sea or coastal defences; to create groynes; to support riverbanks, quays, wharfs; or in protecting bogs and marshlands. One type of such a sheet pile 100 is shown in exaggerated diagrammatical form in Figure 8a and is manufactured by Geoflex NV in the Netherlands. The pile 100, shown in Figure 8a has a male end 107 and female end 104. The male end 107 of the pile is adapted to engage with the female portion so as to lock the piles together thereby forming a contiguous, corrugated wall or barrier (not shown). Sheet pile 100 is typically around 0.2 - 0.4 m wide (i.e. from male to female end), around 0.02 - 0.05 m thick and may be anything from 2m - 8m high.

A particularly successful type of pile is one formed from synthetic plastics material. It will be appreciated that due to the aspect ratio of the particular pile described, it is liable to twisting and flexing when being driven.

Figure 5c shows an underplan view of an alternative gantry 112 with maneuvering rail 26 cut away at opposite sides so as to accommodate sheet piles that have already been driven. It being apparent that without these cutaway portions the manoeuvring rail 26 would impinge on previously sited piles.

A lower brace piece 114 is profiled to receive a pole retaining post support tube 36 or plate 116. Lower brace piece 114 is formed from box sections of mild steel welded together and is attached to the gantry 112 by way of bolts 115 a-d or it can be welded. A locating pin 118 is provided for holding the post in position prior to it being struck by the hammer mass 2. Pin 118 prevents the post from falling through cut-away 180. A spring 120 ensures that the pin 118 is always extended into a position where it engages the pole.

Figure 6 shows diagrammatically an alternative embodiment of the lower brace piece 124, which is reversible. Lower brace 124 is profiled to receive a sheet pile 100 and is in the form of a reversible profile plate 126, which is substantially square and sits within an aperture defined by the square shaped frame of lower brace piece 124 on a shelf 139. Strengthening ribs or gussets 128a - 128d (only 128a and 128b are depicted the other two are hidden) provide strength and support to the frame of lower brace piece 124. The profile plate 126 fits within the periphery of the lower brace piece 124 and enables a non-uniform cross section pile to be oriented in either of two different senses or directions. Reversing the sense of the pile is achieved by flipping the plate 126 over and inserting it into the housing effectively face down. Small cutouts 135 are formed at corner regions of the profile plate 126 so as to accommodate either male or female portions of the pile 100 (as shown in Figure 8b). Retaining pins 130a and 130b act to retain the profile plate 126 in the lower brace piece 124.

Split pins 137 or another suitable catch (not shown) may be inserted through holes 133 in the distal ends of retaining pins 130 to prevent them from slipping from the lower brace piece 124, thus ensuring the plate cannot be displaced from the lower brace piece 124 during operation. A lever mechanism 132 has a handle that can be used to reverse (flip) the sense of the profile plate126 so as to enable a user to locate a pile between himself and the driver or to locate the driver himself and the post.

The lower brace piece and associated housing is removable and may be removed and replaced with an alternative tools support housing. For example one that receives and powers an auger for forming holes (for receiving post of slightly smaller diameter) in harder subsoil, such as chalk. Another alternate tool is a steel rock spike for forming pre-driven holes.

Figures 7a and 7b are views of an impact shoe 136 showing in exaggerated form A channel 138 receives a non-uniform cross section pile 100 (not shown). A solid strike plate 136 is struck by hammer mass 2, shown in Figure 1 (or hammer mass 102 shown in Figure 11b). The impact force from the hammer is distributed evenly across substantially all the surface area of the pile100 by way of the impact shoe 136.

Figures 8a and 8b show another pile gripping device 99. The pile 100 to be hammered into the ground is located by, and held in place by, hydraulically actuated locking jaws.

A movable jaw 106 (shown removed in Figure 8a) grips the pile 100 by applying a compressive friction force against the pile 100 and a thrust plate 108. Thrust plate 108 is formed integrally with the pile-gripping device 99. Different thrust plates may be used in the pile-gripping device 99 so as to provide the proper structure to the jaws of the gripping device.

Figure 8b shows a plan of the gripping device 99 and the arcuate path followed by the jaw 106. Hydraulic ram 110 closes the jaw 106 rotatable about a pivot closing on a pile 100, having non-uniform cross section, by way of hydraulic actuator 110. The pile-gripping device 99 is held in position between the guide rails 34 of the gantry by a collar 170 as shown in Figure 11c. The gripping device 99 is capable of being rotated about the axis of shaft 150, by way of hydraulic ram 185 acting on a cam 187 shown in detail in Figures 9a and 9b.

Piles 100 are driven into the ground, for example along the banks of rivers, so as to form a continuous sheet of piles. Male and female ends are interlocked so as to define a barrier of contiguous sheet piles. In certain situations parallel barriers of sheet piles are erected and concrete poured between adjacent barriers. This adds strength. Such double skin piles with concrete in between are particularly well suited for use as groynes or sea defences where additional strength and bulk is required against impacting waves. In rivers or on marshlands not subjected to extreme tidal flows or wave impacts, a barrier comprising a single layer of sheet piles is usually sufficient.

Figures 9a and 9b show a hydraulic ram 185 and cam 187 in two different positions corresponding to each of two different orientations of the pile-gripping device 99.

Figure 12 is a hydraulic circuit diagram showing an oil reservoir 200 in fluid connection with a high-pressure pump 202 which feeds into a spool valve 204 from where two high pressure hoses 206 and 208 emerge. Hydraulic fluid may be tapped from the so-called third service on many prime movers in order to supply pressure to the hydraulic circuit shown in Figure 12. Hoses 206 and 208 supply a high pressure feed HP1 and HP2 respectively. High-pressure feed HP1 powers rams 214 and 216. HP2 is connected to dump valve 210. Dump valve 210 is described in detail with reference to Figures 13 and 14 below. Dump valve 210 has a large orifice exhaust port 212 through which oil is returned to the reservoir 200 through low- pressure return line LP1.

Describing briefly the operation of the hydraulic circuit, shown in Figure 12, when spool valve lever 204 is in position X, hydraulic fluid is fed into line HP1 and thence to lines 218 and 220. This results in extending rams 214 and 216 (Figure 12), which in turn raise the hammer mass 2/32. When spool valve lever 204 is in position Y, line 208 is closed automatically and line 206 is simultaneously opened. Hydraulic fluid is fed into line HP2. This opens dump valve 212 by overcoming spring resistance 232. Single acting hydraulic ram 232 (shown in Figure 14) in turn displaces piston 228 so that a cut-away collar 229 of piston 228 is aligned with orifice leading to low pressure line LP1. Hydraulic fluid exhausts rapidly through line LP1 to reservoir 200 resulting in the immediate loss of pressure to rams 214 and 216. Hydraulic fluid pressure in lines 218 and 220 is lost and fluid stored in lines 218 and 220 is exhausted to the reservoir 200. This results in rams 214 and 216, being retracted immediately under the weight of the hammer mass 32. The majority of the potential energy of the hammer mass is however converted to kinetic energy which is transmitted as an impulse force to the post or pile (not shown).

Figure 14 shows a dump valve 210 is formed from mild steel or a cast block 222. O- ring seals 224 and 226 seal a cylinder 227 at either end. A chrome steel piston 228 is displaced axially and opens the dump valve. This causes an almost instantaneous pressure loss; with the result that hammer mass 32 falls freely and impacts the post or pile. Hydraulic fluid is allowed to flow through the dump valve 110 under conditions of minimum impedance to a reservoir 200. One or more separate hydraulic feed(s) (not shown) may be tapped off high pressure lines in order to supply hydraulic power to the piston 110, for closing the jaw 106, in Figure 8b and/or the piston 185 for reversing the sense of the pile gripping device 99, shown in Figures 9a and 9b.

It should be noted for convenience that hydraulic actuating rams 214 and 216 correspond to ram 47 shown in Figure 4a, except a pair of rams is employed in the preferred embodiment shown.

Referring briefly to Figures 13 and 14 collectively there is shown a hydraulic dump valve 210, whose exhaust port 212 is in a closed position. The dump valve is capable of rapid pressure drop by rapidly releasing oil in lines 218 and 220 when a reverse pressure is applied via line HP2 when spool valve is lever is placed in position Y.

A single acting hydraulic ram 232 is normally held closed under the action of helical spring 231. Bolt 230 attaches washer 226 restricts the travel of piston 228 so that when spool valve is returned to position X, ram 232 is reversed under action of spring 231. This closes the dump valve 212 enabling high pressure to be passed to lines HP1 and HP2.

The dump valve block 222 is connected to a rigid base plate 223 by way of threaded bolts (not shown) as depicted in the perspective view shown in Figure 13.

It will of course be understood that the present invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention.

Although the impact shoe has been referred to, it will be appreciated that there are certain types of pile with which it need not be used. For example steel sheet piling is sufficiently impact resistant as to not require the use of the impact shoe. Similarly there are situations envisaged where the gantry is lowered and there is no need for the gripping device to be engaged.

Claims

1. A post piling apparatus of the type suitable for driving fence posts into the ground, being attachable to a prime mover, for example a tractor, and comprises: an alignment means operably connected to a prime mover by a support arm; and a driving device suspended from said alignment means, the driving device including means for driving a post or like article into the ground.

2. A post piling apparatus according to Claim 1 wherein the alignment means includes a means for suspending the driving device so that it assumes a plumb position irrespective of the position or pitched angle of the prime mover.

3. A post piling apparatus according to Claim 2 wherein the alignment means comprises a cable or wire hawser or a chain suspended from a support arm.

4. A post piling apparatus according to Claim 1 wherein the support arm is operably connected to and powered by the prime mover.

5. A post piling apparatus according to either of Claims 3 or 4 wherein the support arm of the prime mover comprises an element of the prime mover or attachments therefor designed to lift or manoeuvre other articles.

6. A post piling apparatus has a driving device suitable for suspension from a support arm in operable attachment to a prime mover, the apparatus comprises a means for driving a post or like article into the ground, in which: a hammer mass is confined within a pair of guide rails held in substantially parallel configuration at an impact end and at a lifting mechanism end, said impact end including means for retaining a post in relation thereto and said lifting mechanism end supporting a lifting mechanism operably coupled to said hammer mass.

7. A post piling apparatus according to Claim 6 wherein the apparatus, when suspended from a support arm of a prime mover in use, facilitates the utilisation of substantially all available hammer mass travel distance, as defined by the guide rails, for each impact to a post or like article to be driven into the ground.

8. A post piling apparatus adapted to be fitted to a moveable support arm of a prime mover, wherein the prime mover is included in the group: tractors, particularly agricultural tractors, tractors having a loader mechanism or bail spike; fork lift trucks; 360° excavators; wheeled diggers, having either front or rear lifting means, telescopic handlers; and cranes mounted on vehicles.

9. A post piling apparatus according to any preceding Claim in which the apparatus includes a post retaining plate that is adapted to be secured to the apparatus at the impact end of the guide rails, the plate having a throughbody bore adapted to receive a post.

10. A post piling apparatus according to Claim 9 wherein a locking pin is operable to retain the post within the throughbody bore of the retaining plate.

11. A post piling apparatus according to either Claim 9 or 10 wherein the throughbody bore of the retaining plate is shaped to accommodate a particular post dimension or shape.

12. A post piling apparatus according to any of Claims 9 to 11 wherein the shaped bore of the retaining plate aligns the post and prevents twisting of the post from occurring during the hammering operation.

13. A post piling apparatus according to any preceding Claim having a manoeuvring rail which can be held by a user to enable a torque to be applied to correct any twists.

14. A pile driving apparatus including: a gantry, which is capable of being raised and lowered with respect to the ground and which is adapted to be slung from a suspension point on a prime mover, so that in use, it is plumb; the gantry supporting a hammer mass, which in use applies a force to a pile; an intermediate support means for supporting the pile at a point intermediate the top of the pile and the ground and means for raising the mass so that it may be released to achieve a hammering action.

15. A pile driving apparatus according to Claim 14 including: an impact shoe having a profile adapted to receive a pile, in use the impact shoe transmits an impact force from the mass to the pile.

16. A pile driving apparatus according to Claim 14 wherein the intermediate support means includes a profile plate and a gripping device.

17. A pile driving apparatus according to Claim 16 wherein the gripping device includes a mechanical jaw arrangement that has a relatively displaceable and a relatively fixed jaw.

18. A pile driving apparatus according to Claim 17 wherein the relatively displaceable jaw is actuated using an hydraulic ram.

19. A pile driving apparatus according to any of Claims 16 to 18 wherein the gripping device is supported in a housing, said housing being adapted to receive piles in one of at least two orientations.

20. A pile driving apparatus according to any of Claims 16 to 19 wherein the gripping device is supported in a housing, said housing is rotatable so as to reverse the sense of the gripping device.

21. A pile driving apparatus according to any of Claims 14 to 20 having automatic sensing means to detect the amount of downward displacement required, of the gantry with respect to the ground, following an impact of the mass with a pile.

22. A pile driving apparatus according to Claim 21 wherein the automatic sensing means includes an infrared distance detector, processing means for calculating the amount of displacement required and control means to effect said displacement.

23. A pile driving apparatus according to any of Claims 14 to 22 having a manoeuvring rail.

24. A pile driving apparatus according to Claim 23 wherein control, actuation and release triggers are mounted on the manoeuvring rail.

25. A pile driving apparatus according to either Claims 23 or 24 wherein the manoeuvring rail is displaceable with respect to the gantry.

26. A pile driving apparatus according to Claim 25 wherein the displaceable manoeuvring rail is slidable with respect to the gantry and is mounted thereon using retractable bolts arranged to be received by holes formed in the gantry (or vice versa) so as to allow locking of the gantry with respect to the manoeuvring rail.

27. A pile driving apparatus according to any of Claims 14 to 26 wherein cables for control lines, actuators and release triggers pass inside the guide rails.

28. A pile driving apparatus according to claim 27 wherein the control lines control are mounted on retractable spools so as to take up, or pay out, as required according to the direction of displacement between the guide rails.

29. A post piling apparatus substantially as herein described and with reference to Figures 1 to 4.

30. A pile driving apparatus substantially as herein described and with reference to the Figures, particularly Figures 5 to 14.