GB2551245A

GB2551245A - Trenching machine

Info

Publication number: GB2551245A
Application number: GB1705466.9A
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: 2017-12-13
Also published as: GB201705466D0

Abstract

A boom type trenching machine for mounting on a tractor. The trenching machine has a main body (figure 1, 22) for attachment to a tractor and a trenching boom 12 having an endless excavator chain 20 extending around a pair of sprockets 14, 16 and configured to move vertically with respect to the main body. An elongate crumber bar 38 connected adjacent to the trenching boom, extending generally parallel thereto along a trailing edge and configured to move vertically with the boom. Crumber bar mounting means (figure 1, 36) are adapted to connect the crumber bar to the boom and permit selective linear vertical movement of the crumber bar relative to the boom. Optionally, crumber bar mounting means includes a rack and pinion arrangement, which is driven by a hydraulic motor. Optionally, an auger is provided to move spoil laterally away from the top of a trench formed by the boom.

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 away laterally 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 such issue relates to the engagement of crumbers into the trench. The crumber bar follows the trencher through the trench behind a trailing edge of the boom. However, when a trench is first cut there is initially no space behind the boom into which the crumber can locate. In a variable angle boom where the boom rotates in an arc about an upper end to lower in to the ground the problem is somewhat reduced as the crumber needs only to rotate slightly with respect to the boom to follow it into the hole that is cut. However, in constant angle trenchers where the boom is not rotated but is moved by a vertical translation that is not possible. The present invention provides a solution to these and other problems and improves the engagement of a crumber bar into a trench.

According to the present invention there is provided a boom type trenching machine for mounting on a tractor 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 elongate crumber bar connected adjacent to the trenching boom, extending generally parallel thereto along a trailing edge and configured to move vertically with the boom; and crumber bar mounting means adapted to connect the crumber bar to the boom and permit selective linear vertical movement of the crumber bar relative to the boom.

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 agricultural and grounds keeping tractors in the 150 to 250 horsepower range. 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 crumber bar moves with the boom during normal use when running along a trench and when being lifted clear of a trench. The relative vertical movement of the crumber bar with respect to the boom occurs as the boom is lowered in to the ground to form a trench. As the cutting of a new trench starts the chain operates and the boom is moved down to cut the trench. This is only as wide as the boom and there is no space for the crumber bar, which is moved upward with respect to the boom such that the lower end of the crumber bar remains above the surface. Once the boom has cut to the desired depth the trencher can be advanced by the tractor to extend the trench. Once sufficient space has been free behind the boom, the crumber bar may be lowered into the trench. The movement of the crumber is linear, and for the most part not pivoting, and is generally parallel to the length of the boom or to a line extending between chain sprockets. This movement can be by manual control of an operator or using some form of automatic means to sense the correct position of the crumber relative to the boom and move accordingly.

The crumber bar mounting means may include a rack and pinion arrangement. The rack may be provided on the crumber bar and the pinion may be mounted on the boom such that rotation of the pinion moves the crumber bar up or down. The pinion may be driven by a hydraulic motor. The crumber bar mounting means may include a guide for linear movement of the crumber bar relative to the boom. These may be in addition to a rack and pinion if present. A pipe chute may be connected to the crumber bar through which a rope, cable or pipe may be progressively lain in the trench as it is formed by the boom and the trencher advances. The trencher may have means, such a reel, to dispense that rope, cable or pipe to the chute.

The crumber bar may have a first section comprising a major portion of the overall length of the bar, and a second section at an end thereof, the major axis of the second section being offset slightly to the major axis of the first section. The second section may be at an upper end of the crumber bar. As the crumber is moved up and down the angling of the second section causes a small rotational movement of the crumber bar near the end of the downward journey. This permits a forward projection on the crumber bar to locate in part behind a portion of the lower end of the boom. As the cumber bar lifts the reverse angular movement occurs first to move the forward projection on the crumber bar from behind the boom so that subsequent linear upward movement is not obstructed.

The trenching machine may include an auger to move spoil laterally away from the top of a trench formed by the boom. That auger may be adapted for self-levelling by sliding up and down the boom as it is raised and lowered. This self-levelling auger 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 to prevent clogging. 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 is a side view of a crumber bar and crumber bar mounting means;

Figure 3 is a side view of a pipe chute;

Figure 4a-Figure 4d show various relative vertical positions of the crumber bar with respect to the boom. 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 12 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 spoil 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.

Figure 2 shows in greater detail the engagement of the crumber bar 38 with the crumber bar mounting means 36. In Figure 1 the crumber bar is shown in its lowermost vertical position with respect to the boom, whereas in Figure 2 the crumber bar is shown in its highest position with respect to the crumber bar mounting means (and hence the boom). The crumber bar 38 is generally straight in a first main section 38a, however an uppermost portion 38b is formed at a slight angle to the main section 38a. This allows the crumber bar to undergo a slight rotation about the axis of the pinion as the crumber bar moves down and the section 38b passes through the guide path defined by the rollers 48. This slight rotation allows the forward projection 40 at the lower end of the crumber bar to move in behind the lower end of the boom 12 which might otherwise have been prevented by the projection 40. In effect once the projection 40 has gone past the end of the boom where the idler sprocket and chain start to curve inwards, the rotational movement of the crumber bar arm moves it into closer alignment. In reverse, when the crumber bar 38 is being raised the pinion rotates in an opposite direction and a slight rotational movement occurs to move the projection 40 outwards and away preventing it coming into contact with the trenching chain. As the main straight section 38a passes between the rollers 48 the movement of the crumber bar is only linear. This movement is then generally upward and parallel to the length of the boom 12.

Figure 3 shows the pipe chute 50 which connects to the crumber bar 38.

Figures 4a, 4b, 4c and 4d show a progressive upward movement of the crumber bar and pipe chute combination with respect to the boom. In Figure 4a the crumber bar is at its lowest position relative to the boom and equivalent to that as shown in Figure 1. As the crumber bar starts to move upwards in the transition between the position shown in Figure 4a and that shown in Figure 4b a small rotation occurs (as well as the linear movement) which moves the tip of the projection rearwardly away from the lower end of the chain. Continued rotation of the pinion moves the crumber bar upwards further as shown in Figure 4c until it reaches an appropriate position as shown in Figure 4d. Figure 4d does not show the crumber bar at its uppermost position as a certain further degree of travel is possible as can be seen from Figure 2.

In operation, when a trench is to be formed the trenching apparatus 10 is mounted on a tractor and appropriately connected to the PTO. In this position it is raised above the ground with the ram 30 fully extended. The power system is operated to cause rotation of the trenching chain and the crumber bar is lifted to a raised position such as that shown in Figure 4d, but is high enough to ensure that the lower end is above the ground surface when the desired trench depth has been reached.

The boom with rotating trenching chain is lowered into the ground to form a trench, ensuring that the lower end of the crumber bar remains above the surface. When a desired trench depth has been reached the tractor unit may be operated to drive forwards thus continuing to dig a trench at the leading edge of the boom. As the boom moves forward through the ground forming a trench a space is opened up behind the trailing edge of the boom and once this trench space is large enough the crumber bar may be lowered by rotation of the pinion with respect to the rack such that the crumber bar ends up in a position as shown in Figure 4a. At this point normal operation of the trencher is possible and it may be driven forward operating appropriately and, if desired, dispensing pipe into the trench through the pipe chute. Any vertical adjustment of the boom by operation of the ram 30 to alter the trench depth or ensure consistency with a desired fall in the trench will lift or lower the crumber arm therewith to maintain the relative position. Relative movement of the crumber with respect to the boom is necessary at formation of the trench, but not usually during normal operation. However, of course, adjustment is possible at any stage if desirable.

Claims

1. A boom type trenching machine for mounting on a tractor, 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 elongate crumber bar connected adjacent to the trenching boom, extending generally parallel thereto along a trailing edge and configured to move vertically with the boom; and crumber bar mounting means adapted to connect the crumber bar to the boom and permit selective linear vertical movement of the crumber bar relative to the boom.

2. A boom type trenching machine as claimed in claim 1 wherein the crumber bar mounting means includes a rack and pinion arrangement.

3. A boom type trenching machine as claimed in claim 2 wherein the rack is provided on the crumber bar and the pinion is mounted on the boom such that rotation of the pinion moves the crumber bar up or down.

4. A boom type trenching machine as claimed in claim 1, 2 or 3 wherein the crumber bar mounting means includes a guide for linear movement of the crumber bar relative to the boom.

5. A boom type trenching machine as claimed in claim 3 wherein the pinion is driven by a hydraulic motor.

6. A boom type trenching machine as claimed in any of the preceding claims which further includes a pipe chute connected to the crumber bar through which a rope, cable or pipe may be lain in a trench formed by the boom.

7. A boom type trenching machine as claimed in any of the preceding claims wherein the crumber bar has a first section comprising a major portion of the overall length of the bar, and a second section at an end thereof, the major axis of the second section being offset to the major axis of the first section.

8. A boom type trenching machine as claimed in any of the preceding claims which includes an auger to move spoil laterally away from the top of a trench formed by the boom.

9. A boom type trenching machine as claimed in any of the preceding claims wherein one or more of the sprockets is formed from a laminate of 3 or more sprocket plates joined together.

10. A boom type trenching machine as claimed in claims 9 wherein the sprocket has boot relief cut outs formed in the outer sprocket plates of the laminate.