WO1984004341A1

WO1984004341A1 - Back hoe

Info

Publication number: WO1984004341A1
Application number: PCT/AU1984/000068
Authority: WO
Inventors: Barry Frank Hughes
Original assignee: Barry Frank Hughes
Priority date: 1983-04-22
Filing date: 1984-04-19
Publication date: 1984-11-08

Abstract

A back hoe provided with a slew motor (50) comprising angularly moving rotor (23) and fixed stator (22) defining two working chambers (24, 25) for receipt of pressurized hydraulic fluid so as to cause relative angular movement of rotor (23) and stator (22) to turn an output shaft (34).

Description

"BACK HOE" TECHNICAL FIELD OF THE INVENTION THIS INVENTION relates to back hoes and more particularly to means whereby back hoes may be operated in confined situations.

BACKGROUND ART Back hoes have become common attachments to a range of work vehicles, such as tractors and skid steer loaders, and these require only a suitable mounting point thereon to support the back hoe with motive power supply points to enable their operation. The construction and powering of back hoes comes in a variety of forms, and continuing attempts are made to further perfect the device and its operation. One area of operation of the back hoe is in trenching up against a wall. Where the width of the desired trench bucket is small, the width of the back hoe carrying the bucket is commonly wider than the bucket, meaning that the equipment may not be operated hard up against the wall because of the extra width of the hoe arms and rams beyond the width of the bucket. Thus there is a need for a back hoe construction which is compact, comprises little in the way of width, but still retains the work capacity of existing back hoes. OUTLINE OF THE INVENTION

It is an object of the present invention to produce a back hoe which is compact in construction with no lack of work capacity thereby. It is a further object of the present invention to produce a back hoe with its various arms, rams and journals therefor all located within a width of the hoe so that much narrower buckets than is usual may be operated hard up against walls and other like structures. A still further object of the present invention is a back hoe having a construction and arrangement of parts thereof which is capable of folding into a small volume whilst retaining a substantial reach capable of providing the performance normally expected of such equipment. An additional object of the present invention is the construction of a slew motor which may be employed in the novel back hoe in order to provide slewing movement thereof, which slew motor contributes to the compactness of the back hoe. Another object of the present invention is the construction of a slew motor which may be nested within the arms and rams of the back hoe to which it is attached. Other objects and advantages of the present invention will hereinafter become apparent.

The present invention achieves its objectives by provision of a back hoe for mounting off a suitable support vehicle therefor comprising interconnected, ram operated arms characterised in that a slew motor is provided formed on an axis of a rotating shaft passing therethrough, having both a rotor piece and a stator piece therein, said rotor piece being fixed to said shaft for angular movement therewith and said stator being fixed to the inner surface of a cylindrical sleeve defining a motor cavity having the rotating shaft axially therethrough, said stator piece sealably engaging with said shaft, said rotor piece sealably engaging with said jacket to define two chambers therein between said rotor and stator pieces on opposite sides thereof and passageways engaging said chambers to enable pressurised fluid to be pumped selectively thereto to move said rotor piece angularly with respect to said stator piece, the arms of the back hoe and their operative rams being mounted on said rotating shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment thereof and wherein:- Fig. 1 is a diagrammatic outline of the integers of a back hoe according to the present invention and their points of interconnection; Fig. 2 illustrates the configuration of a slew motor for operation in a back hoe in accordance with the present invention; and

Fig. 3 is a schematic showing the disposition of elements in a ram according to the present invention. METHOD OF PERFORMANCE

Fig. 1 is a purely diagrammatic representation of the various features of a back hoe according to the present invention showing the interconnection points of the integers which combine to produce the novel combination. Item 10 is the axis about which the back hoe rotates and on which a slew motor having an output shaft located on the axis, not shown, is mounted. Affixed to the output shaft of the slew motor is a bridle 11 which extends around the motor to envelope it. The bridle 11 is free to rotate with the output shaft. Bridle 11 provides a connecting point at 13 for a hoe operating ram 20. Ram 20 may comprise a pair of oppositely disposed rams with ram 19 operating between them. The main lower boom arm 17 of the hoe is pivotally connected to the rotating output shaft of the slew motor at a point such as 12, such that ram 20 has a top-dead-centre position over which the boom arm may travel to a rest point. This arises out of the off set positions of the two connecting points 12 and 13 relative to the axis of the slew motor. When arm 17 folds up to the vertical, ram 20 goes past the vertical. Ram 19 connects with the main dip arm 18 which may carry the hoe bucket at the end thereof, at point 14. The main boom arm 17 and the main dip arm 18 are pivotally interconnected at 15. Ram 19 connects at 41 with the lower boom arm 17, a point which places the ram outwardly of the slew motor when arm 17 is raised over the top-dead-centre position of ram 20. To enable this arm 17 may be given an elbow so as to set point 41 outwardly of the axis 10 as is shown in Fig. 3. The arrangement of Fig. 1 enables the generation of a stable over-top-dead-centre rest position and also a very narrow construction. The bridle 11 is a means which is configured in three dimensions to meet the need of supporting pivot pins for the various rams at appropriate locations therefor, without causing interference with either the rams or the lower boom arm 17 when these stretch out and fold back. Where the lower boom arm 17 comprises a pair of side arms on either side of the bridle, the bridle needs to be a narrow fit between the two side arms of the split boom main arm so that the two side arms of the lower boom arm may pass about the sideways extremities of the bridle. A split construction for the main lower boom arm enables the ram 19 to be centrally placed and nest within the main boom arm in the rest position.

The bridle may comprise two suitably curved and interconnected side plates. The two bridle side plates being curved in three dimensions to enable ram 19 to move between and rams 20 to move thereabout, with a slew motor such as is described with respect to Fig. 2 mounted therein, all operating without mutual interference between the side extensions of boom 17.

Fig. 2 shows a cross-section through a slew motor for use in a back hoe as described above. The slew motor 40 comprises a rotating output shaft 34 journalled for rotation in a housing 21 with suitable end seals thereto. The motor may be hydraulically operated with two mating motor pieces 22 and 23 mounted therein. One piece 22 operates as a stator and the other 23 is a rotor piece. Stator 22 is affixed to housing 21 by any suitable means therefor, such as bolts 31 and 30. Rotor 23 is similarly affixed to shaft 34 at 32 and 33. The two pieces define two chambers 24 and 25 therebetween into which a pressurised work fluid such as hydraulic oil may be fed through inlets 27 and 28 to move the rotor one way, or the other, depending upon which chamber receives the pressurised fluid. The two pieces may be suitably channelled to receive a sealing means, not shown, at 29 and 30 to seal the two chambers from one another. The rotor pieces on their extensions, which close over the ports 27 and 28, may be provided with a taper 26 which restricts the outflow of oil from the chamber on pressurised fluid being fed to the other to provide a cushion which slows the back hoe's movement to either of its most angularly turned positions. To move the back hoe back from one of its two most angularly displaced positions, pressurised fluid is fed into the appropriate port to exert a pressure in the chamber operative to push the motor pieces apart and thereby rotate the back hoe mounted thereto. The two motor pieces 22 and 23 may be shaped as shown to enable connection to the shaft and produce suitable chambering. Many different rotor shapes may be devised to effect the slew motor.

In Fig. 3, the parts corresponding to the elements described with respect to Fig. 1 are similarly numbered. Lower boom arm 17 comprises two oppositely disposed side arms, one on each side of the slew motor 50 mounted to its output shaft at the lower end thereof and each actioned by its own hydraulic ram 20. Lower boom arm 17 connects with main dip arm 18, and their relative angular positioning is controlled by ram 19. The lower boom arm 17 has a pivot point 12 set in this case, on the axis of the slew motor, and its operating ram 20 connects with a bridle 11 at point 13, offset from the slew motor 50 axis such that on arm 17 going to the vertical, ram 20 goes past the vertical into an over-top-dead-centre rest position to provide a positively locked rest position whereat an additional, releasable, mechanical latching mechanism might also be provided.

The slew motor 50 is mounted slidably on support rails 56 and 57 which may extend across the front of a skid steer loader when mounted thereto. The sliding mounting of the slew motor on the support rails enables positioning of the back hoe accurately over a trench being dug. Further, by being able to move the back hoe to the side of the rails, a skid steer loader may be parked adjacent a wall and a trench dug up against that wall. The rails 56 and 57 are formed on a suitable frame 58 provided with the requisite connecting points to mate with the standard connectors on a selected support vehicle. The frame

58 may be provided with retractable legs 59 so as to add to the support of the hoe in operation.

The back hoe main dip arm 18 may carry a range of bucket 53 sizes and these are operatively tilted by a suitable linkage 55 between the main dip arm 17 and the bucket 53 actioned by a ram 54.

The hydraulic pressure fluid may be fed to the back hoe from a suitable source in the support vehicle, fed through control lines in the known manner to feed lines 51 passing from the vehicle to the slew motor bridle support to meet with the lower boom arm 17 assembly at a swivelling manifold oscillating with the twin boom cylinder bodies so that normal swivel couplings are not required. The lines 51 may be fed down through the bridle to pass below the slew motor through the point where the boom pivots from to enable large angles of movement without damage to the hoses.

In application on a skid steer loader, the mechanical latch securing the folded boom in its storage position might be a foot operated mechanism. In construction of the slew motor, the stator and rotor pieces may have a constant cross sectional shape along their lengths such that an aluminium extrusion process may be employed in their development.

The sideways movement of the boom upon a support rail assembly might be locked against further movement from a selected position by bolted levers which receive the bolting load in a vertical direction and transmit that load at right angles to produce a clamping action upon the rails. The bridle assembly might be attached to the slew motor shaft at a squared section of that shaft with use of clamping vee-blocks to heavily engage the squared area of the slew motor shaft.

The adoption of the above described slew motor enables construction of a back hoe having a narrow width such that narrow buckets may be employed up against walls. Should the hoe dimensions exceed that of the bucket, the bucket will not be operable against a wall to produce a trench hard up against its base. While the above has been given by way of illustrative example, many modifications and variations as would be apparent to persons skilled in the art may be made thereto without departing from the broad scope and ambit of the invention as herein set forth and claimed in the following claims.

Claims

1. A back hoe for mounting off a suitable support vehicle therefor comprising interconnected, ram operated arms characterised in that a slew motor is provided formed on an axis of a rotating shaft (34) passing therethrough, having both a rotor piece (23) and a stator piece (22) therein, said rotor piece (23) being fixed to said shaft (34) for angular movement therewith and said stator (22) being fixed to the inner surface of a cylindrical sleeve (21) defining a motor cavity having the rotating shaft (34) axially therethrough, said stator piece (22) sealably engaging with said shaft (34), said rotor piece (23) sealably engaging with said jacket (21) to define two chambers (24, 25) therein between said rotor and stator pieces (22,23) on opposite sides thereof and passageways (27,28) engaging said chambers (24,25) to enable pressurised fluid to be pumped selectively thereto to move said rotor piece (23) angularly with respect to said stator piece (22), the arms of the back hoe and their operative rams being mounted on said rotating shaft (34).

2. A back hoe for mounting off a suitable support vehicle therefor as claimed in Claim 1 comprising the slew motor (40) for controlling the angular position of the back hoe, a bridle (11) supported on said rotating shaft for angular movement about said slew motor and connected to the rotating drive shaft of said slew motor, said bridle providing connecting points for the lower boom arm (17) of the hoe and its operating ram (19) actioning the arm (17), the back hoe comprising both a lower boom arm (17) and a main dip arm (18) pivotally connected thereto, said lower boom arm (17) being pivotally connected at a point (12) closer to the axis (10) of said slew motor than the connecting points of the lower boom operating ram (20) to the lower boom arm (17) to provide an over-top-dead-centre rest point for said back hoe.

3. A back hoe for mounting off a suitable vehicle therefor as claimed in Claim 2 wherein said lower boom arm (17) comprises a pair of parallel side arms oppositely disposed on opposite sides of said slew motor (50) with said main dip arm (18) pivotally connected therebetween with the main dip arm operating ram (19) and lower boom side arm operating rams (20) nested therebetween.

4. A back hoe for mounting off a suitable vehicle therefor as claimed in Claim 2 wherein said lower boom arm (17) is provided with a latch means operative in the over-top-dead-centre rest position to releasably secure the boom arm at that position.

5. A back hoe for mounting off a suitable vehicle therefor as claimed in Claim 1 wherein said rotor piece (22) comprises a sealing means (30) engaging said jacket (21) and circumferentially extending lobes on either side providing a tapered slot (26) between said lobes and said jacket (21), said slot opening outwardly with respect to the sealing means.

6. A back hoe for mounting off a suitable vehicle therefor as claimed in Claim 1 wherein said stator piece (22) and rotor piece (23) are extruded lengths of aluminium.

7. A back hoe for mounting off a suitable vehicle therefor as claimed in any one of the preceding claims wherein said back hoe is mounted on support rails (56,57) to enable side shifting of the hoe relative to the support vehicle, said slew motor (50) being slidably hung on said rails by a support means engaged therewith and provided with locking means to lock said support means in selected positions to said support rails (56,57).

8. A back hoe for mounting off a suitable vehicle therefor substantially as hereinbefore described with reference to the drawings.