GB2116605A - Back filling of trenches - Google Patents

Abstract

The invention relates to a method for back-filling an open trench 20 in the ground, which method comprises passing along the mouth of the trench an elongated member 1 carrying a longitudinal rib 4, the rib being in contact with the excavated soil 21 on either side of the trench 20, the member 1 being rotated about its longitudinal axis which is orientated generally horizontally and transversely to the length of the trench 20 whereby soil 21 is moved by the rib 4 into the trench, the member 1 being movable in the vertical plane so that it follows the contours of the land and maintains a substantially constant clearance between the rib 4 and the land. The invention also provides a device for use in the process of the invention. <IMAGE>

Description

SPECIFICATION Method and device for filling trenches The present invention relates to a device for back-filling trenches in the ground, notably those formed during the laying of land drains.

In order to lay a land drain, a trench is dug in the land, usually approximately 10 to 20 cms wide and 1 to 12 metres deep, by a trenching machine.

This deposits the soil dug out to either side of the trench. When the drain pipe has been laid in the bottom of the trench, the soil must be back-filled into the trench. This can be done by hand, but is usually done mechanically by passing an angled scraper blade along each side of the trench to push the soil into the trench. However, this requires that the tractor carrying the blade pass twice along the trench to push soil in first from one side then from the other. This is time consuming and causes compaction damage to the land and to young crops growing along either side of the trench. Also, the scraper blade damages and up-roots the young plants causing further loss of crops.

We have now devised a form of back-filling device which reduces these problems.

Accordingly, the present invention provides a device for back-filling a trench in the ground, which device comprises a member adapted to rotate about its generally horizontal longitudinal axis and carrying one or more longitudinal ribs on its surface, preferably following a helical path with respect to the axis; driving means for rotating the member about its longitudinal axis; means for movably mounting the device upon a transport device for carrying the device across the land; and means for maintaining a predetermined clearance between the rib and the surface of the land over which the device is to travel.

The invention also provides a method for backfilling soil lying to either and or both sides of an open trench in the ground, which method comprises passing along the mouth of the trench an elongated member carrying a longitudinal rib, the rib being in contact with the soil lying on either and/or both sides of the trench, the member being rotated about its longitudinal axis which is orientated generally horizontally and transversely to the length of the trench whereby soil is moved by the rib into the trench, the member being movable in the vertical plane so that it follows the contours of the land and maintains a substantially constant clearance between the rib and the land.

The invention is of especial use in the filling of trenches for land drains, but can be used to backfill other forms of trench, for example in road works and the like, and the term trench is used herein to denote in general any excavation extending longitudinally and having straight, curved, inclined or vertical side walls. It is also preferred to carry the device on a tractor and to provide the drive means for rotating the member from the power take-off point of the tractor. For convenience, the invention will be described herein in terms of a preferred form for such uses as shown in the accompanying drawings in which: Figure 1 is a diagrammatic side view of a tractor carrying the device; Figure 2 is a view from above of the tractor of Figure 1; and Figures 3 and 4 are views of alternative forms of the device of Figure 2.

The device comprises an elongated member 1 which is mounted transversely and rotatably on a tractor 2. The member 1 can be mounted at the rear of the tractor, but is preferably mounted across the front of the tractor, as shown. The member 1 comprises a central axle or shaft 3 about which the member rotates generally parallel to the ground across which the tractor is to be driven. If desired, the shaft 3 can be comparatively thick as opposed to being a slim shaft as shown.

Where a thick shaft 3 is used, this can be of hollow generally cyiindrical construction or a solid shaft of any desired cross-section.

Member 1 has a rib 4 thereon which is to contact the excavated soil at the side of the trench to push it back into the trench. The rib is preferably inclined to the line of intended travel of the device, either by virtue of the axis of rotation being inclined where the ribs 4 run longitudinally substantially parallel to the axis of member 1 as shown in Figure 3; or by forming the rib 4 as an helical rib on member 1 as shown in Figure 2. It is preferred that the rib lies at an angle of from 30 to 700 to the intended line of travel of the device.

The rib 4 can be a simple rib formed on the surface of a thick shaft 3 or can take the form of one or more straight or helical blades mounted longitudinally directly or via radial spokes on shaft 3. Each rib can be a single pitch helix as shown in Figure 1 extending along substantially the whole length of member 1. However, it is preferred to form the helix in two sections of opposed pitch so that rotation of the member 1 draws soil into the middle of the member from each side. In this way the device can straddle the trench and back-fill soil into the trench from both sides in a single pass.

Conveniently, the member is divided into two substantially equal sections and the pitch on each section is from 2 to 3 turns per longitudinal foot of the member.

The rib 4 can be rigid, e.g. it can be made from a suitably shaped strip of metal and can be rigidly mounted on shaft 3 as shown in the drawings.

However, it is also within the scope of the present invention for the rib to be flexible and/or to mount it flexibly upon shaft 3. Thus, for example, the spokes mounting rib 4 on shaft 3 can incorporate a pivot or flex point which permits the rib to be deflected or collapsed when it encounters hard packed earth of other obstruction or for storage.

The flex point is conveniently achieved by forming the radial spoke with a helical spring section or in its mounting on shaft 3. Alternatively, rib 4 can be formed from a flexible material, e.g. a fibre reinforced natural or synthetic sheet or the like. In these cases, the ribs 4 adapt a radically splayed condition due to the centrifugal forces generated as shaft 3 rotates during use.

Member 1 is mounted transversely, preferably at the front of the tractor so that the driver can see where the device is working and so that the wheels of the tractor do not compact excavated soil which is to be moved by member 1. Preferably, the member 1 is mounted with its axis of rotation substantially normal to the intended line of travel where the rib is of helical form. Where the rib extends substantially parallel to the axis of rotation of member 1 , the member is preferably mounted so that its axis of rotation is at an angle, e.g. 30 to 700, to the intended line of travel. The mounting is such that the member 1 is free to move vertically so that it can follow the contours of the land over which it travels.This can be achieved, for example by mounting member 1 in a frame 10 which is carried on a pivot pin 11 at the front of the tractor. Preferably, the mounting permits member 1 to float freely, with the weight of the device carried by two or more ground wheels which also follow the contours of the land.

Alternatively, the device can be carried by a variable height mounting, such as one or more hydraulic arms, whose position is altered by a feeler contacting the ground so that a constant distance between the rib and the ground is maintained. Preferably, the shaft 3 of member 1 is extended laterally to provide an axle to each side upon which are mounted ground wheels 12 (shown dotted in Figure 1).

Member 1 is caused to rotate and thus move earth towards the trench with the rib. Rotation is preferably such that the rib is moving forward when it is in contact with the excavated soil, i.e.

the rib pushes the soil forward and towards the trench. Rotation can be achieved by a number of means. For example, the shaft 3 can be rotated by the ground wheels 1 2. However, it is preferred that the wheels 12 be freely rotating on shaft 3 and that member 1 be rotated by a separate drive.

This drive is, for example, a chain, belt or gear drive 1 3 acting at the centre or at either or both ends of shaft 3 and powered by an hydraulic or other motor 14 on the frame which carries member 1. Preferably the motor is powered by means of an hydraulic pump 1 5 mounted at the rear of the tractor and driven from the power takeoff point of the tractor. Typically, member 1 is rotated at from 200 to 1000 rpm.

With the device of the invention the crown of the ribs can be set to pass at any desired level over the land on which the excavated soil lies, but will typically be set to pass at from 5 to 50 mms above the land level. This clearance is conveniently set by adjusting the size of the wheels 12 on shaft 3.

If desired, the vertical position of the wheels relative to shaft 3 can be made adjustable, e.g. by mounting the wheels on separate axles mounted on vertically adjustable legs extending from the frame carrying member 1.

Member 1 can be made from wide range of materials and can be of any suitable size for the trenches to be back-filled. Typically, member 1 will have a diameter as measured over the crown of the ribs of from 10 to 100 cms and will be from 1 2 to 4 metres wide; and the ribs will extend from 4 to 10 cms radially from the shaft 3 which is from 2.5 to 1 5 cms in diameter.

The invention has been described above in terms of a device having a single auger or paddlelike member 1 carried at the front of a tractor.

However, it is also within the scope of the present invention to have two or more sets of straight or helical longitudinal ribs mounted on one or more members 1. Furthermore, it is not necessary that the axes of rotation or the direction of rotation of the members 1 coincide. For example, the helixes could be carried on two or more shafts 3 inclined to one another (e.g. at 1 50 to 900) to form a V-shape member 1, as shown in Figure 4.

In use, the device is mounted on the tractor and the clearance of the ribs over the ground set to the desired level. The tractor is then driven along the line of the trench 20 straddling the trench.

Member 1 rotates and the rib picks up excavated soil 21 from the sides of the trench and move it towards and into the trench to back-fill it, possibly in only a single pass of the tractor along the trench. Surprisingly, we have found that young crops alongside the trench are not damaged and uprooted with the device of the invention as with a conventional scraper blade, where crop losses as high as 80 or even 90% may occur to either side of the trench.

Claims (10)

1. A method for back-filling soil lying to either and/or both sides of an open trench 20 in the ground, which method comprises passing along the mouth of the trench an elongated member 1 carrying a longitudinal rib 4, the ribe 4 being in contact with the soil 21 lying on either or both sides of the trench, the member 1 being rotated about its longitudinal axis which is orientated generally horizontally and transversely to the length of the trench 20 whereby soil 21 is moved by the rib 4 into the trench 20, the member 1 being movable in the vertical plane so that it follows the contours of the land and maintains a substantially constant clearance between the rib 4 and the land.

2. A device for back-filling a trench 20 in the ground, which device comprises a member 1 adapted to rotate about its generally horizontal longitudinal axis and carrying one or more longitudinal ribs 4 on its surface; driving means 14, 1 5 for rotating the member 1 about its longitudinal axis; means 10, 11 for movably mounting the device upon a transport device 2 for carrying the device across the land; and means 12 for maintaining a predetermined clearance between the rib 4 and the surface of the land over which the device is to travel.

3. A method or device as claimed in either of claims 1 or 2 wherein the rib 4 follows a helical path with respect to the axis of rotation of the member 1.

4. A method or device as claimed in claim 3, wherein the rib 4 is formed in two sections of opposed pitch.

5. A method or device as claimed in any one of the preceding claims, wherein rib 4 and/or its mounting on shaft 3 are flexible and the rib 4 is radially splayed during operation by the centrifugal forces generated by rotation of member 1.

6. A method or device as claimed in any one of the preceding claims wherein the member 1 is a substantially freely floating mount on the transport means 2 and the weight of the member 1 is carried by ground wheels 12 which also set the clearance between the rib 4 and the ground.

7. A method as claimed in any one of the preceding claims wherein the trench is a trench cut in agricultural land in which a young crop is growing.

8. A method as claimed in any one of the preceding claims wherein the member 1 is passed along and astride the trench 20 to move soil 21 into the trench from both sides of the trench in a single pass.

9. An agricultural tractor 2 having mounted transversely at the front thereof a device as claimed in any one of claims 2 to 6.

10. A device or method according to either of claims 1 or 2 substantially as hereinbefore described.