GB2322390A - Erecting fence posts - Google Patents

Abstract

The present invention relates to a machine and method for putting up fence posts placed and supported within a hole made in the ground. The machine 1 comprises a flatbed truck 2 with a platform 4 supporting a rack 5 on which are slidably mounted a ram means 8 for punching a fence post hole in the ground 26 and a ground engaging means 6 with a foot 24. The foot is placed on the ground and the ram means 8 then strikes the ground through a U-shaped aperture in the foot to punch the hole. The foot 24 thereafter stabilises the edges of the hole and may be used as a guide for the placement of a post in the hole, and also to compress any gap around the post. Prior to putting up a post, a sensor 92 may be used to detect the correct distance relative to the last post 88 as the ground engaging means 6 and ram means 8 are moved along the rack 5.

Description

Machine and Method for Putting Up Fence Posts The present invention relates to a machine and method for putting up fence posts, and in particular fence posts placed and supported within a hole made in the ground.

Fence posts are a necessary support for various types of fences along many types of boundary. The fence posts are usually regularly spaced, where soil conditions and the line of the boundary permits. The posts may be made from concrete or metal, or timber treated against decay, depending on the purpose of the fence.

It is usual for post holes to be dug by hand or with a mechanical auger. Once each hole is made, a post will be dropped into the hole, and then the remaining gap surrounding the post will be back-filled, for example with the soil removed to make the hole, or with concrete poured into the gap. Before the post is placed in the hole, soil may tend to fall back into the hole and so the hole must have sufficient clearance to allow for any loss of clearance due to this effect. This, however, means that it can be more difficult to fill the gap, for example by compressing the soil around the hole, to get a tight fit and so support the post securely. Even with mechanical hole drilling equipment, putting up fence posts is labour intensive and relatively slow.

Furthermore, because the location of each hole is determined manually, adjacent posts are not always at the optimum spacing. Although the width of a post provides some tolerance, for example when nailing wooden cross bars end-to-end between posts, spacing errors build up and eventually the posts may be too close, meaning than a cross bar has to be sawn to a shorter length.

Alternatively, posts may be too far apart, in which case the post may have to be removed and put up again.

Other problems may be encountered when putting up fence posts due to the level of the ground being non-horizontal, since then it may not be easy to align the posts substantially vertically. This is often the case when putting up fencing at the sides of motorways, roads, or railways when the line of the fence has to traverse along, or up and down, cuttings and embankments.

According to the invention there is provided a machine for putting up fence posts, comprising a ram means for punching a fence post hole in the ground, a ground engaging means with a foot that may be placed on the ground, the ram means and the foot being configured so that when the ram means strikes the ground to punch the hole the foot is engaged with the ground around at least some of the periphery of the hole.

The hole punched may have any suitable cross-sectional shape, for example circular, square or rectangular, according to the type of post to be placed in the ground.

Since it will normally be necessary for the machine to be movable along the line of a fence to put up a number of posts, the machine may be part of or mounted on a motor vehicle, such as a truck or tractor, or may be towed on a trailer by such a vehicle.

The engagement of the foot with the ground will normally be contact with enough pressure at least to keep the foot engaged with the ground during or after the punching of the hole by the ram means, but not so much pressure so as to risk collapsing the hole after the ram means has been withdrawn from the hole.

Preferably the foot is engaged with the ground prior to the ram means punching the hole in the ground. Although it may be possible to place the foot on the ground to make the engagement after the hole has been punched, the foot will have the most beneficial effect if it is in contact with the ground throughout the process of punching the hole and then placing a post in the hole. The foot may then stabilise the soil, sand or other constituents of the ground in the time during withdrawal of the ram means until insertion of the post, and so help prevent soil, sand or other debris falling back into the hole. Since the clearance between the foot and the ram means may be of the order of a few millimetres, the edges of the foot adjacent the hole may also protect the edges of the hole from damage by a post as it is placed or dropped into the hole.

Optionally, the edges of the foot adjacent the hole have means, such as one or more upstanding lips or flanges to guide a post into the hole.

To provide the maximum protection around the hole the foot preferably has a U-shaped aperture, which may be a square or rectangular U-shape in the case of square or rectangular post holes. The aperture is then configured with respect to the ram means so that the ram means punches the ground through the aperture. Such an arrangement then provides stabilisation and protection of the hole around substantially most of the hole.

It is particularly advantageous if the machine has means to make the foot press against the ground, and the portion of the foot in contact with the ground has a shape adapted to compress the hole laterally when the foot is so pressed against the ground. This pressure is preferably in the form of a repetitive stamping or tamping down of the ground to compress the ground around the post. The machine may therefore cause any gap between the post and the sides of the hole to be filled in and so securely seat the post in the ground.

The post may optionally be held or stabilised by the edges of the aperture in the foot as the tamping down action seats the post securely. Thus a substantially vertical orientation of the post may be maintained as the gaps are filled in.

In order to improve the filling in action, the foot may have at least one rib on the portion thereof in contact with the ground, the rib having a substantially triangular cross-section. The slope of the triangle may then be angled to press soil inwards towards the post.

In a preferred embodiment of the invention, the ground engaging means and the ram means are mounted on a rack which may translate the ground engaging means and ram means in a direction along a line of fence posts put up by the machine. The rack may, for example, be mounted on the bed of a flatbed truck towards a side edge of the flatbed.

The truck or machine is then moved along the ground from the location where the last post was put up by the machine to a location for the next post to be put up. If the machine has means including a sensor which detects a spacing, for example either an incorrect spacing or a correct spacing, between the locations for the last and next posts, then an adjustment may be made of the position of the ground engaging means and ram means on the rack until said spacing is correct. The adjustment may be automated by means of a feedback loop between the sensor and the rack, which may be driven by a drive means such as a hydraulic piston, a rack and pinion drive, or a screw thread drive.

The sensor may conveniently be an optical radiation sensor, particularly a solid state infrared sensor, arranged to detect the location of said last post.

The sensor may extend on a boom arranged to trail behind the machine as it travels from the last fence post to the next fence post. The sensor then comes into proximity with the post after the machine has moved approximately the correct distance. If the length of the boom is adjustable, preferably telescopically adjustable, then the preferred spacing between posts may conveniently be set by adjusting the length of the boom.

Because fence posts are optimally set upright, the machine may have means to align vertically the ground engaging means and the ram means. The means may comprise one or more actuators, the rack and/or the ground engaging means and/or the ram means having a corresponding number of degrees of freedom, and preferably at least two degrees of freedom, to translate or rotate into a vertical orientation when the orientation of the machine deviates from level.

Preferably, one or more orientation sensors are provided so that a vertical orientation may readily be established.

Such devices may also be incorporated in an automatic feedback loop which then drives the ground engaging means and ram means to the correct orientation. Such sensors are most conveniently on the components moved by the actuators so that an error signal from the orientation sensors is automatically driven to zero by the feedback loop.

Because the ram means may remain close over the hole after the hole has been punched, it is advantageous if the machine has means by which the ground engaging means and the ram means may be moved relative to one another. The ram means may therefore be moved out of the way and a fence post placed in a hole punched by the ram means whilst the ground engaging means remains on the ground.

The relative movement may be in the line or at right angles to the fence posts being put up.

Also according to the invention, there is provided a method of putting up fence posts with a machine according to the invention as described above, the method comprising the steps of: placing the ground engaging means on the ground; punching the ground with the ram means to make the hole; withdrawing the ram means from the ground; and placing a fence post in the hole.

After the fence post has been placed in the hole the foot may then be pressed against the ground to compress any gap left between the hole and the post. Preferably, the ram means is moved away from the foot to make space for the post to be placed in the hole.

When the machine is moved from the location of the last post to the location of the next post and before placing the ground engaging means on the ground the method may comprise detecting a spacing, either correct or incorrect, between the locations for the last and next posts with a sensor; and then adjusting the position of the ground engaging means and the ram means until said spacing is correct.

The invention will now be described by way of example, and with reference to the accompanying drawings, in which: Figure 1 is a side view of a machine according to the invention, comprising a flatbed truck, and a rack at the side of the flatbed on which ground engaging means and a ram means are mounted; Figure 2 is a partial side view of Figure 1, showing the rack, ground engaging means and ram means prior to punching a hole in the ground; Figures 3, 4, 5, and 6 are views similar to those of Figure 2, showing the rack, ground engaging means and ram means being used to put up a fence post; Figure 7 is a partial cross-section along a vertical line through the centre of the ground engaging means and ram means, taken along line VII-VII of Figure 3; Figure 8 is a view of a foot of the ground engaging means; and Figures 9 and 10 are side views of the machine of Figure 1, showing how a sensor may be used to detect the correct spacing between adjacent posts, and how the rack may be used to adjust the position of the ground engaging means and ram means prior to putting up the next post.

Figure 1 shows a machine 1 for putting up fence posts, comprising a truck 2 with an integral flatbed platform 4.

A rack 5 is supported along the right hand side of the platform, and on the rack are mounted ground engaging means 6 and a ram means 8.

As shown in more detail in Figure 2, the rack 5 has pair of upright pillars 10,11 at the edge of the platform 4, with a pair of parallel rails 12,13 extending between the pillars. Each pillar is pivotably mounted at a bracket 14,15 to the platform, so that the pillars may tilt about an axis parallel to the side of the platform 4. A hydraulic actuator (not shown) connected to the platform behind each pillar as illustrated is then used to tilt the rack so that it lies in a vertical plane. Such hydraulic actuators may conveniently take their hydraulic supply from the truck.

For clarity in the drawings, the routings of hydraulic hoses to hydraulic actuators have not been shown.

At a forward end of the platform 4 there is a control panel 16 with controls (not illustrated) which may be used to adjust the vertical orientation of the rack 5.

Optionally, the rack may have attached to it a sensor to detect the vertical orientation, and a feedback loop to the rack tilt hydraulic actuator may then automatically adjust the orientation of the rack 5 to vertical.

Preferably, the rack may be tilted at least up to t 25O.

The ground engaging means 6 and ram means 8 are slidably mounted to the rails 12,13, so that the ground engaging means and ram means may be translated together along the rails. When the truck is driven parallel to the line of fence posts being put up, this adjustment may then be used to set the correct spacing between adjacent fence posts.

Any suitable means may be used to effect this translation, such as a motor driven rack and pinion gear or a hydraulically activated piston. The length of the rails 12,13 is sufficient for the ground engaging means 6 and ram means 8 to be slidable over a distance up to 2.8 m.

The construction of the ground engaging means 6 and ram means 8 will be described in detail later, but in additional to being slidably mounted together on the rails 12,13, the ground engaging means 6 may be moved vertically over a distance of up to 900 mm by a hydraulic actuator 18 mounted above the means, and the ram means 8 may be moved forwards sideways over a distance of up to 300 mm away from the ground engaging means 6 by another hydraulic actuator 20 mounted at the side of the ram means. The ram means may also be moved vertically over a distance of distance of up to 150 mm by a similar hydraulic actuator 22 mounted atop the ram means.

The operation of the machine 1 in putting up fence posts will now be explained with reference to Figures 2 to 6.

The truck 2 is driven to a location for a fence post and if necessary the position of the ground engaging means 6 and ram means 8 adjusted along the rails 12,13 until the ram means is over the correct spot for the fence post, as shown in Figures 2 and 3. Then the hydraulic actuator 18 for the ground engaging means 6 is activated to lower the means until a foot 24 at a lower end of the means comes into contact with the ground 26.

Since soft soil may be able to bear less pressure from the foot 24 than hard soil, the hydraulic line to the actuator 18 for the ground engaging means 6 has an adjustable pressure switch so that the actuator 18 stops and holds the foot on the ground 26 when a sufficient back pressure has been provided by the ground. The pressure applied by the foot can therefore be set according to the hardness of the ground.

As will be explained in more detail below, because the ram means 8 is mounted on the ground engaging means 6, the ram means also comes closer to ground. The ram means comprises a hydraulic hammer 28 sold by Krupp GmbH as model number HM140. This is a repetitive action hammer which is activated automatically upon back pressure applied to the hammer 28. The hammer 28 drives a piston 30 which is a hard steel alloy EN24B containing 1.5t nickel. A ramming head 32 affixed to the end of the piston 30 is made from a harder steel alloy EN3OB containing 4.5 nickel.

The hydraulic actuator 22 atop the ram means 8 then lowers the ram means until the head 32 passes through a U-shaped aperture 34 in the foot 24 (see Figure 8) to press against the ground 26, whereupon the hammer 28 is automatically activated to drive the head 32 hard against the ground.

If the ground is soft soil, the head will be punched to the correct depth, in this example about 1 m, in a single stroke. If the ground is hard or stony, several strikes of the hammer may be necessary for the head to punch to the desired depth.

As shown in Figure 5, the hammer 28 withdraws the head 32 from the ground, and the hydraulic actuator 22 then lifts the ram means 8 leaving a hole 36 in the ground. The hydraulic actuator 20 then moves the ram means forwards away from the ground engaging means 6 which all the while remains firmly in contact with the ground 26.

As illustrated in Figure 6, a wooden fence post 38 may then be dropped by hand through the aperture 34 in the foot 24 into the hole 36. The ground engaging means 6 is then activated to stamp or tamp down with rapid short up and down strokes, indicated by the double headed arrow 40, which has the effect of compressing the ground around the post 38 and so secure the post within the hole.

The ground engaging means 6 may then be lifted by its hydraulic actuator 18, whereupon as the truck 2 is driven forwards, the rearwards facing open end of the U-shaped aperture 34 allows the passage of the post so that the foot 24 may withdraw from around the post 38.

An operator of the machine can control the operation of the rack 5, ground engaging means 6 and ram means 8 via the control panel 16. In one mode of operation, all the steps described above may be initiated individually. In another mode of operation, the steps of vertically aligning the ground engaging means and ram means, lowering the ground engaging means and punching the soil 26 with the ram means, withdrawing the ram means and moving it sideways, may all be initiated once as part of one sequence. The tamping down step may then be initiated after placement of the post 38 in the hole, followed by a subsequent initiation of the final steps of lifting the foot 24 and returning the ram means 8 to the aligned position above the foot.

The construction of the ground engaging means 6 and ram means 8 will now be described with reference to Figures 3, 7 and 8. The ground engaging means is slidably engaged with the rails 12,13, by means of a pair of tubular sleeves 42,43 with an open square internal cross-section with clearance for the rails. The sleeves are welded to a back plate 44, the join being reinforced by vertically extending bracing plates 46,47 welded transversely to the bracing plate 44 and the tops of the sleeves 42,43.

The back plate 44 has a circular aperture 48 therethrough centered in an upper half of the plate, and 500 mm below this an annular slot 50 with a radius of curvature centered on the circular aperture 48, and subtending an arc of 500.

A pivot plate 52 parallel and adjacent to the back plate 44 is pivotally held to the back plate by a pair of headed pins 54,55 affixed to the pivot plate. The upper pin 54 pivots in the circular aperture 48 whilst the lower pin 55 traverses the arc of the annular slot 50 when the lower pin 55 is driven through a linkage (not shown) to a hydraulic actuator 56. Since the pivot plate 52 may be thus made to swing in a plane parallel to the side of the truck 2, by +250 from a nominal central orientation, the ground engaging means 6 and ram means 8 may therefore be pivoted to a vertical or near vertical orientation when the truck is sloping uphill or downhill at up to 25 .

Optionally, the pivot plate 52 or another part of the ground engaging means 6 or ram means 8 pivoted by the pivot plate, may have attached to it a sensor to detect the vertical orientation, and a feedback loop to the hydraulic actuator 56 may then automatically adjust the orientation of the ground engaging means 6 and ram means 8 to vertical. Together with the vertical adjustment sensor on the rack 5 and rack tilt hydraulic actuator, these vertical adjustment means provide the necessary two degrees of freedom by which post holes may be punched vertically.

The pivot plate has along its sides a pair of vertical slides, one of which 58 is partially visible in Figure 7.

A vertical movement plate 60, parallel to the other plates, is slidably engaged at its edges in the slides 58.

The hydraulic actuator 18 is mounted atop the pivot plate 52 of the ground engaging means 6 and may therefore drive the vertical movement plate 60 up and down with respect to the pivot plate 52.

An extension 62 removably affixed to the vertical movement plate 60 extends downwards towards to ground 26, with the foot 24 removably affixed to a lowermost portion of the extension 62.

The vertical movement plate 60 has a pair of parallel horizontal slides 64,65 which engage with a matching pair of brackets 66,67 on a ram back plate 68 parallel with the other plates. The hydraulic actuator 20 for the sideways movement of the ram means is mounted to the side of the vertical movement plate, and although this would not be visible in the section along the centre line VIl-VIl, this has been included in Figure 7 in dashed outline. This actuator may therefore move the ram back plate 68 sideways, away from the plates 44,52,60 comprising the ground engaging means 6.

A ram vertical movement plate 70 parallel with the other plates is slidably mounted on the ram back plate 68 between a pair of slides, one of which 72 is partly visible in Figure 7. The hydraulic actuator 22 is mounted atop the ram back plate 68 to move the ram vertical movement plate 70 up and down.

All the plates 44,52,60,68,70 are made from steel, being 1250 mm tall, up to 600 mm wide, and 25 mm thick.

A horizontal shelf 74 is welded to and projects forwards from an upper portion of the ram vertical movement plate 70. The shelf 74 has at its sides a pair of reinforcing brackets, one of which 76 is visible in Figure 7, the brackets 76 being welded to an underside of the shelf and the sides of the ram vertical movement plate 70.

The hammer 28, which is 900 mm long, is securely bolted to the ram vertical movement plate and the shelf 74.

The ramming head 32 in the present example has a rectangular cross-section, is axially aligned with the aperture 34 in the foot 24, as shown in Figure 8 in the dashed outline 78 inside the aperture 34. As can be seen from the drawing, there is a close tolerance between the size of the hole formed by the ramming head and the sides of the aperture, so that the aperture may better stabilise the sides of the hole.

The foot 24 has a pair of parallel ribs 80 on an undersurface thereof. The ribs have a protruding crosssection of a triangle having both inwardly and outwardly sloping sides relative to the aperture 34. The ribs are arranged close to the edges of the aperture to better apply the inwardly compressive force to the ground to fill in any gap between the hole and the post.

Optionally, a third rib could be placed at right angles between the ends of the pair of ribs 80, adjacent the base 81 of the U-shaped aperture, so that ribs extended substantially around the periphery of the aperture 34.

The foot 24 is removably affixed to the extension 62 by a flange 82 extending upright from the foot. The flange has a triangular bracing extension 83 across the side of the foot nearest the base 81 of the aperture 34 so that the foot is braced against back pressure from the ground 26.

The three sides of the U-shaped aperture 34 each have a lip 84,85,86 tapering upwards and outwards from the aperture, so that when a post is dropped into a hole, the post is guided into the hole by the lips.

Figures 9 and 10 show how a sensor may be used to adjust automatically the spacing between adjacent posts. The machine 1 has just been used to put up a fence post 88, and the truck 2 has then driven forwards from this post.

The truck however, is a bit too far forward for the next post to be correctly located.

A boom 90 extending rearwardly of the flatbed platform 4 has an optical radiation sensor 92 at its end. The boom is affixed to the ground engaging means and therefore the distance to the sensor may be used as a measure of the correct distance between the last and next post to be put up. The length of the boom 90 may be telescopically adjusted so that the correct distance may be selected at will. The sensor in this example is an infrared sensor sold as model number E61DP6 by Cutler Hammer Limited.

An operator of the machine then uses the controls 16 to make the ground engaging means 6 and ram means 8 translate rearwards along the rack's rails 12,13 until the sensor 92 detects the presence of the last post 88, whereupon the position of the ground engaging means is correctly set, in this example, at 1.8 m from the last post.

Either before or after this operation, the ram means 8 is then moved back into alignment with the foot 24 following which the next post may be put up in the correct location with respect to the previous post 88.

Once at least a pair of posts are correctly set up, the construction of the fence may be completed, for example with horizontal rails between the posts.

The truck 2 as illustrated has a fully laden weight of up to 8 tonnes. The forces exerted by the ram means 8 and tamping down of the ground engaging means 6 are limited to be approximately equal to about half the weight of the truck.

A machine as described above may be driven across ground which slopes at up to 250 from horizontal, and the vertical orientation of the ground engaging means and ram means then adjusted to put up vertical fence posts. Apart from the step of manually dropping or placing the posts in the formed holes, the process of setting up posts may be substantially mechanised and automated, thereby improving the efficiency of the fence building operation.

The use of sensors to vertically adjust the orientation of the ground engaging means and ram means, as well as to gauge and set the correct spacing between adjacent fence post holes, will speed up the fence building operation.

With such a machine, it is possible to set up posts to an accuracy of 4 to 5 mm from the previous post, and at a rate of up to 1 minute per post.

Although the rack, ground engaging means and ram means have been illustrated and described on the right hand side of the flatbed platform, these could alternatively be mounted either at the rear or left hand side of a platform. In this case, the U-shaped aperture in the foot would preferably be oriented with the opening to the aperture facing backwards so that the foot is withdrawn from about the post placed in the hole as the truck is driven forwards.

Claims (16)

Claims

1. A machine for putting up fence posts, comprising a ram means for punching a fence post hole in the ground, a ground engaging means with a foot that may be placed on the ground, the ram means and the foot being configured so that when the ram means strikes the ground to punch the hole the foot is engaged with the ground around at least some of the periphery of the hole.

2. A machine as claimed in Claim 1, in which the foot is engaged with the ground prior to the ram means punching the hole in the ground.

3. A machine as claimed in Claim 1 or Claim 2, in which the foot has a U-shaped aperture through which the ram means punches the ground.

4. A machine as claimed in any preceding claim, in which the machine has means to make the foot press against the ground, and the portion of the foot in contact with the ground has a shape adapted to compress the hole laterally when the foot is so pressed against the ground.

5. A machine as claimed in Claim 4, in which the foot has at least one rib on the portion thereof in contact with the ground, the rib having a substantially triangular cross-section.

6. A machine as claimed in any preceding claim, in which the ground engaging means and the ram means are mounted on a rack which may translate the ground engaging means and ram means in a direction along a line of fence posts put up by the machine.

7. A machine as claimed in Claim 6, in which the machine may be moved along the ground from the location where the last post was put up by the machine to a location for the next post to be put up, the machine having means including a sensor which detects a spacing between the locations for the last and next posts and which then adjusts the position of the ground engaging means and ram means on the rack until said spacing is correct.

8. A machine as claimed in Claim 7, in which the sensor is an optical radiation sensor arranged to detect the location of said last post.

9. A machine as claimed in any preceding claim, in which the machine has means to align vertically the ground engaging means and the ram means.

10. A machine as claimed in any preceding claim, in which the machine has means by which the ground engaging means and the ram means may be moved relative to one another so that a fence post may be placed in a hole punched by the ram means whilst the ground engaging means remains on the ground.

11. A method of putting up fence posts with a machine as claimed in any one of Claims 1 to 11, the method comprising the steps of: a) placing the ground engaging means on the ground; b) punching the ground with the ram means to make the hole; c) withdrawing the ram means from the ground; and d) placing a fence post in the hole.

12. A method as claimed in Claim 11, comprising the step after step d) of: e) pressing the foot against the ground to compress any gap left between the hole and the post.

13. A method as claimed in Claim 11 or Claim 12, comprising the step between steps c) and d) of: f) moving the ram means away from the foot to make space for the post to be placed in the hole.

14. A method as claimed in any one of Claims 11 to 13, comprising the steps before step a) of: g) moving the machine from the location where the last post was put up to a location for the next post to be put up; h) detecting a spacing between the locations for the last and next posts with a sensor; and i) adjusting the position of the ground engaging means and the ram means until said spacing is correct.

15. A machine for putting up fence posts substantially as herein described, with reference to and as shown in the accompanying drawings.

16. A method of putting up fence posts substantially as herein described, with reference to and as shown in the accompanying drawings.