GB2551419A

GB2551419A - Trenching machine

Info

Publication number: GB2551419A
Application number: GB1705468.5A
Authority: GB
Inventors: Rodney Fulford Dennis
Original assignee: Harry Maria Jurgens
Current assignee: Harry Maria Jurgens
Priority date: 2016-04-08
Filing date: 2017-04-05
Publication date: 2017-12-20
Also published as: GB201705468D0

Abstract

A boom type trenching machines for mounting on a tractor to form a trench in a surface. The trenching machine has a main body 22 for attachment to a tractor and a trenching boom 12 having an endless excavator chain extending around a pair of sprockets 14, 16 and configured to move vertically with respect to the main body. The trenching machine has an auger assembly 60 including an auger 62 driven by the excavator chain to rotate and move spoil dug by the chain away from the trench. The auger assembly is moveably mounted on the boom such that as the boom moves vertically into and out of the trench, within a range of vertical positions, the auger maintains a constant position relative to the surface 11. Optionally, the auger assembly is slidably mounted on the boom. Optionally, the auger assembly comprises a carriage that is slidably mounted to the boom, the auger being rotatably mounted to the carriage. Optionally, biasing means to urge the auger assembly downwards are provided, having a hydraulic piston operatively linked to the auger assembly.

Description

Trenching Machine

The present invention relates to boom type trenching machines and improvements to these.

Boom type trenching machines are well known and generally comprise a boom with an endless trenching chain that rotates over 2 or more sprockets and has teeth or buckets. The boom may be lowered into the ground, such that rotation of the chain breaks up the ground to form a trench. These machines can be mounted or integrally formed with a tractor unit that carries them and moves them over a surface in which a trench is to be formed. The tractor unit also provides power to drive the chain and lift and lower the boom. They may comprise a crumber that follows the boom through the ground to improve trench formation. One or more auger may be provided to move spoil dug from the trench lateral away so that it does not fall back in.

Such machines suffer certain limitations and it is an aim of the present invention to provide an improved trencher. One issue concerns the positioning of the auger relative to the ground surface regardless of the depth of a trench that is being dug. The auger should be positioned at a desired distance above the surface, usually close, and that distance may vary relative to the tip of the boom depending on trench depth and undulations in the ground surface. In addition, erratic obstacles such as rocks can be in the path of the auger and these can cause damage.

According to the present invention there is provided a boom type trenching machine for mounting on a tractor moving over a surface in which a trench is to be formed, the trenching machine comprising: a main body for attachment to a tractor; a trenching boom having an endless excavator chain extending around a pair of sprockets and configured to move vertically with respect to the main body; an auger assembly including an auger that is driven by the excavator chain to rotate and move spoil dug by the chain away from the trench, wherein the auger assembly is moveably mounted on the boom such that as the boom moves vertically into and out of the trench, within a range of vertical positions, the auger maintains a constant position relative to the surface.

As used herein the term tractor means a mobile power unit to power and move the trencher. It may be a specific device intended solely for trenching or it may be something to which various attachments may be coupled. The present invention finds particular utility in connection to standard agricultural and grounds keeping tractors with a 150 to 250 horsepower output. Ideally the present invention has couplings to connect to the carrying and lifting linkages of such tractors and for connection to the power take off (PTO) and hydraulic pumps thereof.

The auger may be configured in a variety of ways known in the art and may extend lateral of the trench by a variable amount. More than one auger may be provided and the or each auger may extend to one or both sides of the trench.

Ideally the auger assembly is slidably mounted on the boom. The auger assembly may comprise a carriage that is slidably mounted to the boom, with the auger being rotatably mounted to the carriage. The auger assembly may comprise an auger sprocket that engages the excavator chain to cause rotation of the auger. The boom may define a path for sliding movement of the auger assembly. The auger assembly, may run up and down the boom along that path. The inter-engagement of the path and the auger assembly can be achieved in a many different ways, but the provision of a rail along the boom and runners on the auger assembly that engage that rail has been found effective.

The path for sliding movement is preferably provided along a lateral leading edge of the boom. In this regard a leading edge refers to that edge that is at the front as the boom moves forward forming a trench. The trailing or rear edge is the opposite side. The path for the sliding movement of the auger assembly may be curved. The curve may be outward with respect to a line extending between the pair of sprockets of the trenching boom. In effect such a curve is convex. This curve ensures that the auger assembly is forced outward against the chain by an appropriate varying amount (depend on vertical position between the chain sprockets) which ensures constant chain tension regardless of the position of the auger assembly.

The present invention allows the auger to adjust its position relative to the boom so that it can maintain a fixed position relative to the ground surface during trenching. However, when the trencher is not in use (such as when it is being transported) it is lifted from the ground and the auger needs to lift clear. A stop or other form of abutment may be provided on the boom to limit the lower position of the auger assembly relative to the boom. In this way as the boom lifts vertically the auger moves down the boom, but at a desired point the auger assembly engages the stop and cannot move further along the boom. Continued upward movement of the boom lifts the auger assembly from the surface.

In order to keep the auger in the correct place relative to the surface and prevent undesired upward movement, the trencher further includes biasing means to urge the auger assembly downwards. Rotation of the chain would tend to impart an upward force on the auger and this is counteracted by the biasing means. The biasing means may comprise a hydraulic piston operatively linked to the auger assembly to urge the auger assembly downwards. That linkage may be through an arrangement of levers that can accommodate the range of lifting movements that the trencher can perform.

The upward movement of the auger assembly may cause compression of the piston or biasing means. It is this compression that resists that upward movement, however there are circumstances where it is desirable for the auger to lift. Such circumstances include lifting of the trencher from the ground when operation ceases or lifting to go over an obstacle such as a rock. The piston may have a pressure release mechanism such that when the pressure exceeds a threshold value, compression of the piston and upward travel of the auger assembly is permitted. That pressure release mechanism may close again when the pressure drops and the biasing means may then urge the auger to return to the previous position.

The trencher may be further provided with an elongate crumber bar connected to the trenching boom, extending generally parallel thereto along a trailing edge of the boom and configured to move vertically with the boom. The crumber bar may be mounted using crumber bar mounting means adapted to connect the crumber bar to the boom and to permit selective linear vertical movement of the crumber bar relative to the boom. The crumber bar may therefore be moved vertically with respect to the boom so that the crumber may be located in a trench behind the boom after a sufficient length of trench has been cut. This movable crumber bar is discussed in the applicant’s co-pending patent application.

The trenching machine may have one or more sprockets that has been formed from a laminate of 3 or more sprocket plates joined together. Such a sprocket ideally forms the idler sprocket at the lower end of the boom. The laminate sprocket may have boot relief cut outs formed in the outer sprocket plates of the laminate. This laminated sprocket is discussed in the applicant’s further co-pending patent application.

In order that it be better understood, but by way of example only, the present invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a representational side view of a trenching machine according to the first embodiment of the present invention;

Figure 2 shows a simplified side view of the trencher when the boom is fully raised and the auger assembly is at the lower end of its extent of movement on the boom;

Figure 3 is similar to Figure 2 but the boom is shown in its lowermost position relative to the main body and the ground surface;

Figure 4a shows the auger assembly and the biasing means as in Figure 2;

Figure 5 shows the auger assembly and biasing means in an alternative position when the boom is lowered;

Figure 6a-Figure 6c show the trencher in various vertical positions relative to the ground surface showing the auger assembly with respect thereto. A first embodiment of trenching machine generally indicated 10 is shown in Figure 1. This comprises a boom 12 that extends downwards. The angle of the boom relative to the surface 11 can be set as appropriate, but in this embodiment it is fixed at approximately 72° to the horizontal. At the upper end of the boom there is a drive sprocket 14 and at the lower end there is an idler or soil sprocket 16. An endless trenching chain comprising a series of links 18 extends around the drive sprocket and idler sprocket. Only one link 18 is shown, however the path of the drive chain is marked by line 20. The chain carries teeth (not shown) that break up the ground.

The trencher 10 has a main body in the form of a frame 22 which is coupled to a tractor (not shown) at linkage points 24. By these linkages the frame and the boom 20 which is supported thereon may be carried and transported by the tractor and lifted as a whole. A power connection 26 to the power take-off mechanism (not shown) of the tractor is provided and this is coupled to a drive chain mechanism 28 which links to the drive sprocket 14. By this mechanism the power of the tractor may be used to cause rotation of the drive sprocket and hence rotation of the trenching chain. This causes movement of teeth provided on the trenching chain and thus forms a trench as the tractor unit moves the boom forward through the ground. A hydraulic ram 30 is provided on the frame 22 in such a way that extension of that ram causes the frame to lift which in turn lifts the boom and other components relative to the anchoring point on the tractor. By control of this ram the extent to which the boom 12 extends into or out of the ground and thereby the depth of a trench can be controlled.

Crumber bar mounting means 36 are connected to the frame in a fixed arrangement with respect to the boom such that these move up and down with the boom. They may connect directly to a part of a boom assembly or to the frame such that it is fixed with respect to the boom. A crumber bar 38 is mounted in the crumber bar mounting means 36. The crumber bar 38 is generally elongate with a forward projection 40 at a lower end. A rack 42 is provided along the crumber bar 38 and this co-operates with a pinion 44 driven by a hydraulic motor 46 provided on the crumber bar mounting means 36. A guide path defined by a pair of rollers 48 is located above the pinion. The crumber bar is held by the rollers 48 and by the rack and pinion arrangement. Rotation of the pinion causes the crumber bar to move up or down with respect to the boom and through the guide path. A hollow pipe chute is connected to the crumber bar and moves up and down therewith. The pipe chute comprises a path to guide pipe or like flexible elongate component from the reel 52 down into the trench for rearward dispensing from the chute opening 54.

Mounted to the leading (or front) edge of the boom 12 is an auger assembly 60. This auger assembly comprises augers 62 adapted to move soil dug from the trench laterally away from the trench top to ensure that it does not fall back in as the trencher passes. The auger assembly is slidably mounted on the boom 12 so that it may move up and down relative to the boom to ensure a consistent position with respect to the ground surface 11. The auger assembly 60 has an auger sprocket 64 which engages with the trenching chain such that rotation of the chain causes rotation of the auger in an appropriate direction.

The auger assembly 60 engages with a rail 72 defined by or along a leading edge of the boom 12. The auger assembly 60 comprises a main body 74 that is slidably mounted to that rail and one or more laterally extending auger 62 that is driven by the rotation of the trenching chain over the auger sprocket 64.

The leading edge of the boom defining the slide path for the auger assembly is curved. This curve ensures that, as the auger assembly moves up and down the boom, the extent by which the curve extends from a notional line between the centres of the drive sprocket 14 and the idler sprocket 16 varies. This varying degree ensures that appropriate tension is maintained within the trenching chain regardless of the vertical position of the auger assembly relative to the boom.

In Figure 2 the auger assembly 60 is shown slid to the lowest extent of its range of movement along the boom. The assembly will, as the boom lifts, move down until it engages the stop 66 at which point the continued upward movement of the boom will lift the auger assembly. This movement is linked through to the piston 68 causing compression thereof. This compression increases internal pressure in the piston 68 until it reached a threshold at which point a pressure relief system operates in order to release fluid from the piston and allow the piston to compress. That compression of the piston permits the continued upward movement of the auger assembly with the boom. The linkage of the piston to the auger assembly is shown in Figure 4 and 5 where the piston is coupled through a series of levers 70 to the auger assembly. Figure 3 shows the arrangement of Figure 2 (in both of these Figures various parts including the crumber arm and power train have been omitted for clarity) in a lowered position. In this arrangement it can be seen that the auger assembly is higher up the boom and is positioned close to the ground surface 11 such that rotation of the auger will move spoil sideways across that surface away from the top of the trench. In Figure 3 the auger assembly is shown at the upper end of its range of sliding movement along the boom.

In Figure 6a the lower end of the boom is entering the upper part of the ground and extends slightly below the surface 11. At this point the vertical position of the auger assembly may be manually adjusted relative to the ground by adjusting the biasing mechanism. Although the boom is deeper in Figure 6b the auger assembly remains at the same position relative to the ground surface as shown in Figure 6a. Likewise, in Figure 6c the boom has moved to a maximum depth and the auger assembly has slid up its slide path so that remains in a constant position just above the surface of the ground. If a reverse movement from the configuration shown in Figure 6c towards the position shown in Figure 6b occurs the auger assembly would slide down the leading edge of the boom under the urging of the biasing mechanism. On lifting, when the configuration reaches the uppermost part as shown in Figure 6a, the auger assembly has reached the lowermost extent of its sliding movement. At this point continued upward movement of the boom causes the auger assembly to come into contact with stop 66 on the boom such that further relative downward movement is no longer possible. At this point the upward movement of the boom causes compression of the piston and an increase in internal pressure. As mentioned above, once this passes the threshold (which is set to ensure no damage to the system and which may be adjustable) the piston will release and the auger assembly may continue to rise with the boom up to the uppermost position identified in Figure 2. As can be seen in Figure 2, the trencher as a whole has been lowered such that the ground engaging parts are resting on the ground. Once the boom has been raised to its maximum extension by the frame the lift associated with the tractor linkage may be used to raise the trenching machine as a whole away from the ground.

Pressure release achieved during upward movement of the auger assembly may be recharged into the cylinder by appropriate means. For example, in positioning of the auger relative to the ground during set up of a trenching run the cylinder may be appropriately charged with hydraulic fluid to extend by the desired amount. Alternatively, some form of accumulator arrangement may be used to accommodate the over-pressure and then recharge the cylinder as appropriate.

The moveable nature of the auger relative to the boom allows not only the dynamic and automatic alignment of the auger with the ground surface regardless of alterations in the depth of the trenching cut, but it also permits the augers to ride up and over serious obstacles encountered during trenching. For example, if a significant stone is in the path of the auger next to the trench the pressure release mechanism would permit the auger to rise up and over this obstacle if sufficiently problematic such that damage to the auger caused by the impact is reduced or prevented. This would occur automatically and the auger could return to its normal operating position under the influence of the biasing means once past the obstacle.

Claims

1. A boom type trenching machine for mounting on a tractor moving over a surface in which a trench is to be formed, the trenching machine comprising: a main body for attachment to a tractor; a trenching boom having an endless excavator chain extending around a pair of sprockets and configured to move vertically with respect to the main body; an auger assembly including an auger that is driven by the excavator chain to rotate and move spoil dug by the chain away from the trench, wherein the auger assembly is moveably mounted on the boom such that as the boom moves vertically into and out of the trench, within a range of vertical positions, the auger maintains a constant position relative to the surface.

2. A boom type trenching machine as claimed in claim 1 wherein the auger extends lateral of the trench to one or both sides of the trench.

3. A boom type trenching machine as claimed in claim 1 or claim 2 wherein the auger assembly is slidably mounted on the boom.

4. A boom type trenching machine as claimed in claim 3, wherein the auger assembly comprises a carriage that is slidably mounted to the boom, the auger being rotatably mounted to the carriage.

5. A boom type trenching machine as claimed in any of the preceding claims wherein the boom defines a path for sliding movement of the auger assembly.

6. A boom type trenching machine as claimed in claim 5 wherein that path for sliding movement is provided along a lateral leading edge of the boom.

7. A boom type trenching machine as claimed in claim 5 or claim 6, wherein the path for the sliding movement of the auger assembly is curved.

8. A boom type trenching machine as claimed in claim 7, wherein the curve is outward with respect to a line extending between the pair of sprockets of the trenching boom,

9. A boom type trenching machine as claimed in any of the preceding claims, where a stop is provided on the boom to limit the lower position of the auger assembly relative to the boom such that as the boom lifts vertically at a desired point the auger assembly engages the stop such that continued upward movement of the boom lifts the auger assembly from the surface.

10. A boom type trenching machine as claimed in any of the preceding claims, which further includes biasing means to urge the auger assembly downwards.

11. A boom type trenching machine as claimed in claim 10, in which the biasing means to urge the auger assembly downwards comprise a hydraulic piston operatively linked to the auger assembly.

12. A boom type trenching machine as claimed in claim 11 wherein upward movement of the auger assembly compresses the piston.

13. A boom type trenching machine as claimed in claim 12 wherein the piston has a pressure release mechanism such that when the pressure exceeds a threshold value, compression of the piston and upward travel of the auger assembly is permitted.

14. A boom type trenching machine as claimed in any of the preceding claims wherein there is further provided an elongate crumber bar connected to the trenching boom, extending generally parallel thereto along a trailing edge of the boom and configured to move vertically with the boom.

15. A boom type trenching machine as claimed in claim 14 which further includes a crumber bar mounting means adapted to connect the crumber bar to the boom and to oermit selective linear vertical movement of the crumber bar relative to the boom.