US3624935A - Trencher having an endless digger and adjustable augers - Google Patents

Abstract

AN ADJUSTABLE BOOM CARRYING AN ENDLESS DIGGING CHAIN OPRATED HYDRAULICALLY AND HAVING A DOWNWARDLY EXTENDING OFFSET TIP WITH THE END OF THE BOOM ADJUSTABLE FOR CHAIN LOOSENING AND TIGHTENING. TRANSVERSE AUGERS MOVE EXCAVATED DIRT AWAY FROM THE TRENCH FORMED BY THE DIGGING CHAIN AND THESE ARE ADJUSTABLE ALONG THE LENGTH OF THE BOOM TO COMPENSATE FOR THE SWINGING MOVEMENT TO THE BOOM WHICH ALLOWS A TRENCH TO THE DUG AT VARIOUS DEPTHS AS THE DIGGING PROCEEDS.

Description

Dec. 7, 1971 R. G. LAWRENCE TRENCHER HAVING AN ENDLESS DIGGER AND ADJUSTABLE AUGERS Filed Sept. 2, 1969 5 Sheots-Shcot 1 m "P T T an $0 :0 2' m n 0 IO INVUNTOR ALBERT HWRE/Vaa BY v' vA- v (.212,

ATTORNEY R. e. LAWRENCE 3,624,935

TRENCHER HAVING AN ENDLESS DIGGER AND ADJUSTABLE AUGERS Dec. 7, 1971 5 Sheets-Sheet 2 Filed Sept.

INVENTOR Dec. 7, 1971 R. a. LAWRENCE 3,624,935

TRENCHER HAVING AN ENDLESS DIGGER AND ADJUSTABLE AUGERS Filed Sept. 2, 1969 I5 Sheets-Sheet 5 FIG 4 FIG. 7

FIG. 5

INVENTOR 754% v (lee,

ATTORNEY United States Patent 3,624,935 TRENCHER HAVING AN ENDLESS DIGGER AND ADJUSTABLE AUGERS Robert G. Lawrence, Swift Current, Saskatchewan, Canada, assignor to Saskatchewan Power Corporation, Regina, Saskatchewan, Canada Filed Sept. 2, 1969, Ser. No. 854,459 Int. Cl. E021 5/06 U.S. Cl. 37-86 2 Claims ABSTRACT OF THE DISCLOSURE An adjustable boom carrying an endless digging chain operated hydraulically and having a downwardly extending offset tip with the end of the boom adjustable for chain loosening and tightening. Transverse angers move excavated dirt away from the trench formed by the digging chain and these are adjustable along the length of the boom to compensate for the swinging movement of the boom which allows a trench to be dug at various depths as the digging proceeds.

This invention relates to new and useful improvements in hydraulic trenching devices, particularly devices adapted to form or cut a trench for the installation of gas lines or the like.

Conventional trenchers normally utilize an endless chain having cutter blades or semi-buckets thereon and these are rotated on a boom which can be raised or lowered with relation to the ground. They are normally driven from the source of power such as tractor, by means of chain drive and are normally provided with a transverse auger which moves the excavated soil away from the cut upon either side thereof.

The present invention consists of several improvements in existing devices.

Firstly, the trenching chain is driven directly by an hydraulic drive. The hydraulic motors are coupled directly to the final drive shaft of the trenching device thereby eliminating all side load on the hydraulic motors and accomplishing a power transmission by torsional load only. This assures long hydraulic motor life under the severe conditions encountered by this type of machine.

Secondly, the hydraulic drive permits a reversible digging chain assembly. In other words the chain can travel in either a forward trenching direction or a reverse trenching direction.

The need for this type of operation occurs particularly in rocky land or in areas where yards are completely landscaped with hedges, shrubs, sidewalks, driveways and the like. The reversible chain allows the machine to undercut such shrubs, driveways and the like to a certain extent without damaging them.

The reversible chain also allows the operator to back off the chain it a rock becomes jammed between various drive components and the chain. This often happens in rocky terrain.

The hydraulic drive on the trenching device itself eliminates a great portion of shock load to the structural portions of the machine, thus decreasing the amount of maintenance necessary on all parts and especially on the digging chain assembly itself. The hydraulic drive also offers numerous digging chain speeds which is particularly suited to frost conditions and for the purpose of Bell-holing.

A second improvement is the fact that the transverse soil clearing anger is adjustable hydraulically. The purpose of these angers on the trenching device is to move the excavated dirt into small spoil piles as the trencher progresses in a forward direction. This is best accom- 3,624,935 Patented Dec. 7, 1971 plished by keeping the anger at about two inches from ground level, therefore it is necessary to be able to adjust the augers as various trench depths are desired.

For example, in the process of trenching a gas service, it is generally necessary to vary the depth of trench from thirty inches to approximately five feet in order to provide suflicient ground cover in the first instance and in the second instance to reach the gas main for tie-in purposes. The operator must therefore be able to adjust the auger height with relation to the boom as he proceeds along the trench. The present system incorporated in this device allows a variable adjustment at any time and during the operation of the machine.

A third important improvement is the fact that the digging chain assembly can be varied so far as tension is concerned. A device is incorporated on the outer end of the boom which again is controlled by the use of an hydraulic cylinder. This allows the chain tension to be adjusted continuously by the operator for the following reasons.

Firstly, due to the design of the variable auger adjustment, the chain must be adjusted at the same time as the augers in order to maintain the correct tension on the chain.

Secondly, depending upon the type of soil in which the machine is operating, the digging chain should be adjusted to maintain a proper tension or slack in the digging chain as the case may be. For instance, when operating on frozen soil, the digging chain should be relatively tight, thus preventing bounce or snap in the digging chain.

In soil with gravel or small rocks, the digging chain should be relatively loose, thus allowing these rocks to squeeze out rather than bind in between the chain link and sprockets.

Thirdly, if an object becomes jammed in the chain and it is impossible to rotate the digging chain in the opposite direction by use of the hydraulic motors, it is possible to slacken the digging chain, thus allowing the object to fall free of the boom.

The fourth important improvement is the provision of an offset cutting tip at the end of the boom. The outer sprocket wheel on the present device is offset from the boom axis downwardly by approximately four inches. The purpose for this is when digging in extremely tough conditions such as frost or dry gumbo type soil, it is necessary to reduce the effective cutting length of chain down to a minimum number of teeth in contact with the ground, thus getting a higher degree of breakout force at the teeth in contact with the soil. This offset head accomplishes this purpose thereby allowing the device to trench in extremely tough digging conditions.

With the foregoing in view, and such other or further purposes, advantages or novel features as may become apparent from consideration of this disclosure and specification, the present invention consists of the inventive concept which is comprised, embodied, embraced or included in the method, process, construction, composition, arrangement of parts, or new use of any of the foregoing, herein exemplified in one or more specific embodiments of such concept, reference being had to the accompanying figures in which:

FIG. 1 is a top plan view of the boom assembly with the chain and transverse anger removed for clarity.

FIG. 2 is a side elevation of FIG. 1 showing the chain in dotted line.

FIG. 3 is a side elevation of the offset cutting tip per se, enlarged in scale in respect to FIGS. 1 and 2.

FIG. 4 is an end view of the transverse auger sliding support.

FIG. 5 is an end view of the boom showing the auger carrier slide.

FIG. 6 is a schematic view of the hydraulic system for the trencher.

FIG. 7 is a schematic View of the hydraulic accesory and tractor creeper circuitry.

In the drawings like characters of reference indicate corresponding parts in the different figures.

Before proceeding with the description of the device, it should be appreciated that it is designed to be attached to the rear of a tractor or similar source of motive power having a source of power for the operation of the hydraulic systems. The boom assembly shown in FIGS. 1 and 2. is adapted to be mounted for vertical raising and lowering upon the rear of the tractor, said raising and lowering being operated hydraulically as will hereinafter be described.

Proceeding therefore to describe the invention in detail, reference character 10 shows the main boom which is of square cross section and is preferably hollow not only for weight considerations but also so that hydraulic lines and boom tip extension cylinder can be located therein.

The rear end 11 of the boom is enlarged as illustrated and a cross member 12 also of square cross section is secured upon each side of this enlarged portion. Brackets 13 extend rearwardly from the ends of the cross members 12 by which the device may be mounted for the aforementioned vertical pivoting action. An hydraulic piston and cylinder assembly 14 (see FIG. 7) is secured upon each side of the boom just forwardly of the cross members 12 between clevises 15 and extend upwardly to the main supporting frame extending from the tractor (not illustrated). These are connected to the. hydraulic pump 16 and operated through a four-way valve 17' so that the main boom assembly may be raised and lowered within limits.

The transverse auger assembly collectively designated 17 consists of an anger section 18 upon each side of the boom flighted in opposite directions so that if the auger assemblies are rotated in one direction, and soil engaged thereby is urged outwardly away from the boom upon each side by the two sections.

These are mounted on a shaft 19 in turn supported within pillow blocks 20 (see FIG. 4). These pillow blocks are secured to the underside of an auger carrier 21 which consists of a main body portion 22 having reverse angle plates 23 secured to the upperside thereof as clearly shown in FIG. 4.

These angle plates engage over longitudinally extending rails or plates 24 which in turn are secured in spaced relationship from the underside 25 of the main boom, said spaced relationship being provided for by the elongated strip 25 as clearly shown in FIG. 5.

An hydraulic piston and cylinder assembly 26 is pivotally secured by one end 27 to a bracket 28 which in turn extends rearwardly from side plates 29 secured to the underside of the boom. The piston rod 30 extending from the piston and cylinder assembly 26, is secured by means of a clevis (not illustrated) to the aforementioned auger carriage body 22 so that extension or retraction of the piston rod 30 causes the auger assembly 18 to be moved fore and aft with respect to the boom, it being understood that in operation, the boom extends downwardly and forwardly from the tractor on an inclined plane.

Secured to the rear bifurcated portions 11A and 11B of the enlarged portion 11, is a pair of pillow blocks 31. A main drive shaft 32 is journaled for rotation within these pillow blocks and a main drive sprocket wheel 33 is secured to this shaft.

Hydraulic motor mounting plates 34 are secured fo the rear sides 35 of each of the transverse extensions 12 and hydraulic motor mounts 36 extend outwardly from these plates at right angles thereto. Hydraulic motors 37 are secured to these plates and are coupled directly to each end of shaft 32 and these are connected to a further pump 38 (see FIG. 6) operated by a gas engine 39 or similar source of power.

A four-way valve 40 determines the direction of rotation of these motors and hence the direction of rotation of the main drive sprocket wheel 33.

An idler sprocket wheel 41 is journaled for rotation between the two side plates 29 hereinbefore described and further idler sprocket wheels 41A and 41B are journaled for rotation between corresponding side plates 29A and 29B extending upwardly from the upper side 42 of the main boom 10.

An offset tip assembly collectively designated 43 extends forwardly and downwardly from the end 44 of the main boom assembly 10 and is shown in detail in FIG. 3. It consists of a square cross sectioned main body portion 45 slidably receivable within the end 44 of the main boom and being capable of limited extension with relation thereto. A piston rod 46 is pivotally secured within the end 47 of this portion 45, by means of transverse pin 48 and this piston rod forms part of a piston and cylinder assembly 49 operated by four-way valve 50* shown in FIG. 7.

And endless digging chain assembly 51 having cutter blades 52 thereon, extends around the idlers 41, 41A, and 41B, and around the main drive sprocket 33. It also extends around a sprocket wheel 53 journaled for rotation upon shaft 54, mounted between end plates 55 extending from the end 56 of the tip assembly 43. It should be observed that these end plates incline forwardly and downwardly from the end 56 so that pin 54 is below the longitudinal axis of the tip body 45 and the boom 10.

This means that when the boom is inclined downwardly, a relatively small number of teeth engage the soil thus assisting in breaking through this soil under tough conditions as hereinbefore described.

The aforementioned piston and cylinder assembly 49 controlling the extension and retraction of the tip assembly 43 within the end 44 of the boom, permits the tension of the chain 51 to be adjusted Within limits as hereinbefore described.

Reference to FIG. 7 will show that a further four-way valve assembly 57 operates the piston and cylinder assembly 26 for the auger adjustment and also in this circuit, a further four-way valve assembly 58 controls an hydraulic motor 59. This motor 59 is connected to the drive of the tractor or source of power thus allowing it to be moved forwardly at a relatively low speed, said speed being infinitely variable within limits due to the characteristics.

Both FIGS. 6 and 7 show conventional control valves and the like in circuit with the hydraulic systems but as these are conventional, it is not thought necessary to describe sa'me in detail.

From the foregoing it will be appreciated that a boom assembly is provided in which the chain assembly is driven directly by hydraulic motors thus giving variable speed and forward and reverse operations to the digging chain assembly.

Furthermore it will be appreciated that the tension of the chain assembly 51 can be varied within limits by the extension and retract of the tip 43. In this connection also it should be observed that the idler sprocket wheel 53 mounted in the tip is below the longitudinal axis of the boom.

Next it should be appreciated that the transverse auger 18 can be adjusted within limits along the length of the boom thus regardless of the depth at which the auger is cutting.

Finally it should be observed that the hydraulic motor 59 allows the source of power such as a tractor to be controlled as to the forward and reverse speeds, easily and readily and at a speed suited to the digging conditions.

Various modifications can be made within the scope of the inventive concept disclosed. Accordingly, it is intended that such concept and not for the purpose of limiting protection to any particular embodiment thereof, but that only such limitations should be placed upon the scope of protection to which the inventor hereof is entitled, as justice dictates.

What is claimed to be the present invention is:

1. In a trenching device adapted to be supported upon a source of motive power and including a source of hydraulic pressure; a boom pivoted by one end thereof to said source of motive power, an endless digging chain mounted around said boom for movement thereon, an hydraulic motor operatively connected to said endless chain for rotatably moving said chain in either direction around said boom, a pair of transversely situated oppositely flighted, auger assemblies, one upon each side of said boom and situated externally of said chain, means to move said transverse auger assemblies along the length of said boom within limits, a downwardly offset tip on said boom and a sprocket journalled in said tip, said digging chain engaging around said sprocket, said means to move said transverse auger assembly along the length of said boom within limits, including a longitudinally extending rail secured to the underside of said boom, an augar carrier slidably mounted on said rail for longitudinal movement therealong, an auger shaft journalled for rotation transversely of said carrier, an hydraulic piston and cylinder assembly operatively connected between said boom and said carrier for moving same along said rail.

2. The device according to claim 1 in which the other end of said boom is movable inwardly and outwardly within limits, relative to the remainder of said boom, for adjusting the tension in said digging chain.

References Cited ROBERT E. PULFREY, Primary Examiner C. D. CROWDER, Assistant Examiner US. Cl. X.R. 37191 A

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