AU2003257866B2 - Improvements in Skid-Steer Vehicles - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant Actual Inventor(s) Address for Service: Invention Title: Jaden Charters Pty Ltd Douglas William Mcliwraith Bridgman Drive, Reedy Creek, Queensland, Australia CULLEN CO Patent Trade Mark Attorneys, 239 George Street Brisbane QId 4000 Australian Improvements in Skid-Steer Vehicles The following statement is a full description of this invention, including the best method of performing it, known to us: SThis application is a divisional application filed in respect of an invention disclosed in Australian patent application no. 65424/99. The disclosure of Spatent application no. 65424/99 is incorporated herein by reference.

_This invention relates to improvements in hydraulically driven vehicles. In particular, the invention is directed to a self-levelling mechanism for a IN lifting arm of a compact multi-purpose skid-steer mini-loader.

00 BACKGROUND ART There are various types of known skid-steer loaders, perhaps the most 10 popular being that sold under the trade mark BOBCAT. The popularity of these loaders is due, at least in part, to their manoeuvrability and versatility. The hydraulic skid-steer drive enables the loader to turn sharply, and eliminates the need for complex steering and gearing mechanisms. The interchangeability of the loader bucket with other tools, such as a posthole digger, trench digger, rotary sweeper, etc.

enables a single machine to provide a variety of functions.

In recent years, a smaller, stand-on version of the skid-steer loader has become popular for lighter tasks and/or operation in confined places. Examples of these smaller loaders, commonly known as "mini-loaders" are those sold under the trade marks KANGA T M (in the United States of America) and JADEN TM (in Australia).

This invention relates to improvements in skid-steer vehicles, particularly, although not solely, skid-steer vehicles of the mini-loader type.

SUMMARY OF THE INVENTION This invention relates principally to a self-levelling mechanism for a lifting arm of a hydraulically driven vehicle, such as a skid-steer mini-loader. (The lifting arm normally has a bucket mounted to its free end and, for that reason, is also known as a bucket arm). While the invention will be described with particular reference to a lifting arm having a bucket mounted thereon, the self-levelling mechanism can be used for other attachments mounted on the lifting arm.

The self-levelling mechanism operates in association with the bucket arm to automatically maintain the bucket or other attachment at a constant orientation (relative to the horizontal) as the arm is raised and lowered.

In one embodiment, the automatic levelling mechanism comprises a Qfirst sprocket connected to a bucket mounting plate and rotatable therewith about its pivot axis, and a second sprocket mounted on the vehicle, typically with its axis collinear the pivot axis of the bucket arm. The first and second sprockets are _connected by an endless chain, which may include rigid linkages.

The second sprocket is normally held stationary (to maintain the bucket or other attachment at a constant orientation). That is, due to the interconnection of 0 the two sprockets, as the bucket arm is rotated, the mounting plate sprocket is turned (slightly) by the chain connected to the (fixed) second sprocket to counteract the rotation of the first sprocket relative to the second sprocket which would otherwise

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occur due to rotation of the lifting arm. This maintains the bucket or other attachment at a substantially constant orientation.

A hydraulic cylinder may be connected to the second sprocket for tilting the bucket/attachment as and when required. Rotation of the second sprocket by the hydraulic cylinder causes a corresponding rotation of the first sprocket, and hence, the orientation of the bucket/attachment is changed, e.g. to empty the bucket.

By utilising a chain and sprocket arrangement, the bucket levelling mechanism can be housed under the bucket arm (and substantially concealed from view). Unlike known bucket levelling mechanisms which comprise rigid linkages protruding above the bucket arm, the bucket levelling mechanism of this invention can be concealed under the arm.

Typically, the hydraulically driven vehicle has an on-board power plant for powering the vehicle. The power plant comprises a tank serving as a reservoir for hydraulic fluid, a hydraulic pump located within the tank, and a motor (typically an internal combustion engine) mounted on top of the tank, the motor driving the pump via an upright shaft projecting into the tank.

The vehicle may also be provided with a pivoting panel which facilitates access to the engine bay in which the power plant is located. This pivoting panel is typically the console panel, and is angled or 7-shaped, forming the rear wall and top of a cover for the power plant. By pivoting open the console panel, the engine bay is exposed, thereby facilitating insertion, removal and servicing of the engine, pump and associated components.

The vehicle chassis may comprise two spaced parallel side walls, typically steel plates, fixed to either side of the tank which forms the oil reservoir for the vehicle hydraulic drive system. The side walls themselves may constitute opposite side walls of the tank.

The use of the oil reservoir tank as part of the chassis enables the chassis to be constructed in compact form and reduces the amount of material required, yet still allows the chassis to have the required strength and rigidity.

IN Preferably, the lifting arm is generally of inverted channel 0 configuration and has a relatively wide central web. The web forms the front face of the arm which is located at the front of the vehicle. Hence, from the front of the vehicle, the arm appears as a single wide flat plate, creating an aesthetically pleasing

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N 10 appearance. The flat web of the arm also protects hydraulic equipment and the bucket self-levelling mechanism which are located under the arm.

Preferably, a "quick hitch" locking mechanism is provided for mounting an attachment, such as a bucket, to the mounting plate on the arm. This mechanism includes at least one toggle arm on the rear of the mounting plate which automatically locks the attachment to the mounting plate when the mounting plate is inserted into mounting brackets on the attachment. In this manner, the attachment may be mounted and locked to the mounting plate remotely by the vehicle operator by manoeuvering the mounting plate into the mounting brackets on the attachment.

Other features and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front perspective view of a mini-loader according to one embodiment of the invention, Fig. 2 is a side elevation of the mini-loader of Fig. 1, Fig. 3 is a rear perspective view of the mini-loader of Fig. 1, Fig. 4 is a side perspective view of the mini-loader of Fig. 1, with console panel opened, Fig. 5 is a perspective view of the engine and pump mechanism of the mini-loader of Fig. 1, Fig. 6 is a perspective view of the bucket hitch mechanism of the miniloader of Fig. 1, and Figs. 7 and 8 are side views of the automatic bucket levelling Q)mechanism of the mini-loader of Fig. 1, with the bucket in the lowered and raised

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positions, respectively.

_DESCRIPTION OF PREFERRED EMBODIMENT As shown in Figs. 1-5, a skid-steer vehicle, in the form of a "mini- INO loader" 10, comprises a chassis formed from two spaced parallel steel plates 11, 12 00 oO fixed on either side of a metal tank 13 (shown in dotted outline in Fig. The steel Splates 11, 12 may be machine cut and may form the actual sides of the tank. The tank (Ni 13 not only serves as an oil reservoir for the hydraulic drive system of the mini-loader, S 10 but also forms a box-like structural part of the chassis. This form of construction is relatively simple and economical to manufacture.

A tread plate 14 extends between the rear ends of the side plates 11, 12, as shown in Fig. 3. The tread plate 14 serves as a platform on which the operator stands (and rides) during operation of the mini-loader. Preferably, the tread plate 14 is weighted, to act as a counterbalance to the load carried by a bucket 15 at the front of the mini-loader.

The mini-loader 10 is provided with two pairs of wheels 21. A mudguard 22 may be provided above the wheels 21 on each side of the mini-loader.

The mudguards 22 are typically welded, bolted or otherwise fixed to the side walls 11, 12. The mudguards 22 may be used to carry equipment or accessories such as a battery and/or toolbox.

Typically, only one set of wheels is driven hydraulically by the miniloader power plant. That is, either the front or the rear wheels are driven hydraulically.

The driven wheels are each rotated by a hydraulic motor driven by a hydraulic pump via valve(s). Each wheel in the other (non-driven) set of wheels is driven from a respective one of the hydraulically-driven wheels by a chain 24. In this manner, the wheels on each side of the mini-loader rotate in unison.

The tank 13 which forms a structural part of the chassis also serves as the oil reservoir for the hydraulic system used to drive the mini-loader. As shown in Fig. 5, the hydraulic pump 30 is located within the reservoir 13. The pump is used to supply hydraulic fluid under pressure to drive the hydraulic motors coupled to the driven set of wheels 21, the hydraulic cylinders which operate the bucket arm, and auxiliary equipment which may be mounted to the mini-loader. The hydraulic pump is itself driven by a motor, typically an internal combustion engine 31, mounted to

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the top plate of the tank 13. The engine 31 has a vertical drive shaft which extends Sinto the tank 13 to drive the hydraulic pump N The above described arrangement of engine, pump and oil tank enables the power plant to be constructed in a very compact form. This in turn, allows the size INO of the mini-loader to be reduced, permitting the mini-loader to be used in confined 00 oO spaces. In addition, by locating the pump 30 in the tank 13, a separate intake hose is tt not required for the pump.

The bucket 15 (or other attachment) is removably mounted to a mounting plate 16 by a "quick hitch" locking mechanism described later. The mounting plate 16 is pivotally connected to one end of a bucket arm 17, the other end of which is pivotally mounted on a pivot pin 18 extending between the side walls 11, 12 of the chassis.

The bucket arm 17 is of inverted channel configuration comprising a web and two end walls, the web being wide relative to the end walls. Such configuration provides a neat, aesthetically pleasing appearance since only the large flat web of the bucket arm is visible from the front of the mini-loader. The wide flat web of the channel-shaped bucket arm 17 not only hides the hydraulic hoses and cylinders under the arm, but also protects such hydraulic equipment and the bucket self-levelling mechanism (described below) from dirt and damage.

A 7-shaped console panel 19 is located between the side plates 11, 12, as shown in the drawings. The panel 19 forms the rear and top of a cover for the power plant in the engine bay. The lower end of the console panel 19 is pivotally mounted to the side walls 11, 12, enabling the whole console panel 19 to pivot rearward (as shown in Fig. 4) and expose the engine bay of the mini-loader.

The engine bay is closed by pivoting the console panel 19 upwardly to the position shown in Figs. 1-3. At that position, the top forward ends of the control panel 19 can be bolted or otherwise fixed to the side plates 11, 12. Control levers on the console panel are connected to the remainder of the hydraulic operating system by flexible hoses which permit the console panel 19 to be opened and closed.

The ability to pivot the control panel 19 rearward and open up the engine bay allows clear access to the engine 31. This facilitates servicing of the engine, as well as the installation and removal of the engine 31 and/or pump 30 from Q)the tank 13. When such access is not required, the console panel can be pivoted upwardly and forwardly to close the engine bay and form a very compact body.

SThe illustrated mini-loader is provided with a "quick hitch" locking _mechanism which enables an operator to mount, and lock, the bucket 15 to the mounting plate 16 without the operator having to dismount from the tread plate 14. As INO shown in Fig. 6, the bucket 15 is provided with a pair of spaced C-shaped flanges or 00 oo brackets 33 on the rear thereof. In use, the operator manoeuvres the mounting plate 16 to locate within the C-shaped brackets 33. This can be achieved by inserting the tilted (Ni mounting plate 16 into the brackets 33, and then rotating the mounting plate 16 10 hydraulically.

The mounting plate 16 also comprises a pair of toggle arms 34 pivotally mounted to the rear of the plate 16 at spaced locations corresponding to the mounting brackets 33 of the bucket 15. When the mounting plate 16 is inserted into the C-shaped mounting brackets 33, the toggle arms 34 pivot upwardly as they ride over the nose 33A of the bottom portion of each mounting bracket 33. However, once each toggle arm 34 clears the step at the back of each nose portion, the toggle arm drops down into a slot 33B and securely locks the mounting plate 16 in the mounting brackets 33. It would therefore be apparent that the bucket 15 can be mounted and locked, to the mounting plate 16 by manoeuvring the mounting plate 16 from the operator's console.

To remove the bucket 15 from the mounting plate 16, the outer extension 34A of each toggle arm 34 is kicked down to release the toggle arm from the slot 33B, and the plate 16 is tilted and withdrawn from the brackets.

Another advantageous feature of the illustrated mini-loader is an automatic bucket levelling mechanism, depicted schematically in Figs. 7 and 8.

Although bucket levelling mechanisms are known, such mechanisms typically comprise parallelogram linkages and hydraulic cylinders extending upwardly from the bucket arms. In the illustrated bucket levelling mechanism, a chain and sprocket arrangement is used to maintain the bucket at a constant orientation automatically as the bucket arm is raised and lowered.

As shown in Figs 7 and 8, the bucket 15 is mounted on the mounting plate 16 at the distal end of the bucket arm 17 whose proximal end is pivotally mounted on the pivot pin 18 extending between the side walls 11, 12. A hydraulic 8 O cylinder 35 is mounted between the bucket arm 17 and a transverse bar mounted between lower portions of the side walls 11, 12. The hydraulic cylinder 35 is driven by Sthe hydraulic pump 30 to rotate the bucket arm 17.

_A sprocket 36 is fixed to the mounting bracket 16, and is rotatable therewith about the pivot axis of the mounting bracket 16. (The term "rotatable" as INO used herein also means partially rotatable). An endless chain 37, or similar linkage, 00 oo connects sprocket 36 with a sprocket 38 mounted on the chassis near the proximal end of arm 17, typically collinear with the pivot axis as arm 17. A hydraulic cylinder 39 is connected between sprocket 38 and a fixed lower point on the chassis of the mini- 10 loader. The cylinder 39 is driven by pump 30, via a control valve on the console panel, to rotate sprocket 38. (In practice, only a small angular rotation is required). As sprockets 36 and 38 are linked by chain 37, any rotation of sprocket 38 causes a corresponding rotation of sprocket 36, thereby causing tilting of the bucket mounted on plate 16. In this manner, hydraulic cylinder 39 is used to vary the orientation of bucket As the bucket arm 17 is raised and lowered by cylinder 35, and with sprocket 38 fixed in position by cylinder 39, the fixed lengths of chain 37 between sprockets 36, 38 cause rotation of sprocket 36 relative to the arm 17 such that the sprocket 36 maintains a substantially constant orientation relative to (fixed) sprocket 38. The rotation of sprocket 36 compensates for the otherwise opposite rotation of the distal end of arm 17 about the sprocket 38. Thus, the bucket 15 is automatically maintained at a substantially constant orientation as the bucket arm 17 is raised and lowered.

To change the orientation of bucket 15, e.g. to empty the bucket, the cylinder 39 is actuated to rotate sprocket 38, and hence sprocket 36 via the chain linkage.

It will therefore be apparent to those skilled in the art that the above described chain and sprocket arrangement results in the bucket 15 being self-levelling.

That is, the bucket 15 maintains its orientation relative to the horizontal as the arm 17 is raised and lowered (unless sprocket 38 is itself rotated by cylinder 39). Moreover, the chain and sprocket mechanism allows greater angular displacement of the arm 17 and bucket 15 than would otherwise be possible with a rigid parallelogram linkage in the same confined space. The self-levelling mechanism is able to be concealed within 9 0 the channel-shaped arm 17, and does not detract from the appearance of the miniloader.

SThe foregoing describes only one embodiment of the invention, and modifications which are obvious to those skilled in the art may be made thereto without departing from the scope of the invention. For example, the central portions IN of the chain may be replaced by rigid links.

00 Furthermore, the improvements disclosed herein such as the selft levelling mechanism, can be applied to other machinery and not only skid-steer vehicles.

S 10 The term "comprising" is used in the following claims in the inclusive sense, to mean the stated integers without necessarily excluding other integers.

Claims (19)

1. A hydraulically driven vehicle having a chassis, a lifting arm having one end pivotally mounted to the chassis, and Ia mounting member pivotally connected to the other end of the lifting 00 0 arm for mounting a bucket, scoop or other attachment, further comprising a levelling mechanism for automatically maintaining the mounting member at a substantially constant orientation as the arm is raised and lowered, the 10 levelling mechanism comprising a first sprocket fixed to the mounting member and rotatable therewith about a pivot axis of the mounting member, a second sprocket mounted to the vehicle at a pivot axis of the lifting arm, and an endless chain interconnecting the first and second sprockets, such that as the lifting arm is raised or lowered, the first sprocket is rotated relative to the arm to maintain the mounting member at a substantially constant orientation.

2. A vehicle as claimed in claim 1, wherein the second sprocket is mounted for rotation about the pivot axis of the lifting arm, further comprising means for rotating the second sprocket about its axis to thereby vary the orientation of the mounting member and any attachment mounted thereon.

3. A vehicle as claimed in claim 2 wherein the rotating means is a hydraulic cylinder controllable by an operator of the vehicle.

4. A vehicle as claimed in any preceding claim, wherein the lifting arm is generally of inverted channel configuration and has a relatively wide central web which forms a front face of the lifting arm.

A vehicle as claimed in claim 4, wherein the levelling mechanism is substantially concealed within the lifting arm.

6. A vehicle as claimed in any preceding claim, further comprising a locking mechanism for fixing a bucket or other attachment to the mounting member, the locking mechanism including at least one toggle arm on the rear of the mounting member which locks the bucket or other attachment to the mounting member.

7. A vehicle as claimed in claim 6, wherein the bucket or other Q- attachment has at least one C-shaped mounting bracket adapted to receive the mounting member therein, the toggle arm being adapted to ride over an end portion of the mounting bracket as the mounting member is inserted in the bracket, and automatically locate in a recess in the bracket to thereby lock the mounting bracket to the mounting member. IN

8. A vehicle as claimed in any preceding claim wherein the chassis 0 comprises two spaced parallel side walls fixed to respective opposite sides of a tank which forms an oil reservoir for a hydraulic drive system for the vehicle.

9. A vehicle as claimed in claim 8, wherein the side walls are steel plates O S 10 which form the respective opposite sides of the tank, further comprising a tread plate extending between the rear ends of the side walls to form a platform upon which an operator may stand.

A vehicle as claimed in any preceding claim, wherein the vehicle has a power plant mounted to the chassis for powering movement of the vehicle and operation of the lifting arm.

11. A vehicle as claimed in claim 10, further comprising a panel pivotally mounted at its lower end to the chassis, the panel being pivotable between a closed position whereat it at least partially covers the power plant and an open position which provides access to the power plant.

12. A vehicle as claimed in claim 11, wherein the panel is a console panel having controls thereon for operation of the vehicle.

13. A vehicle as claimed in claim 11 or 12, wherein the panel forms a rear wall and a top of a cover for the power plant.

14. A vehicle as claimed in any preceding claim, wherein the vehicle is a skid-steer loader.

A levelling mechanism for a lifting arm of a skid-steer loader or similar vehicle, the lifting arm having a mounting member pivotally mounted to a free end thereof and pivotable about a first axis, the mounting member being adapted to have a bucket, scoop or other attachment mounted thereto, and the other end of the lifting arm being pivotally mounted so that the arm is pivotable about a second axis,, the levelling mechanism comprising a first sprocket connected to the mounting member and rotatable therewith about the first axis, a second sprocket mounted on the vehicle chassis, and a chain interconnecting the first and second Q)sprockets, such that as the arm is raised and lowered, the first sprocket is (N automatically rotated about the first axis to maintain the mounting member and any Sattachment mounted thereto at a substantially constant orientation.

16 A levelling mechanism as claimed in claim 15, wherein the second sprocket is mounted with its axis collinear with the second axis, and the chain is an INO endless chain encircling the first and second sprockets. 00 00

17. A levelling mechanism as claimed in claim 16, wherein the second sprocket is rotatable about the second axis, and means are provided for rotation of the Ssecond sprocket, whereby the orientation of the mounting member and any attachment 10 mounted thereto can be varied by rotation of the second sprocket.

18. A levelling mechanism as claimed in any one of claims 15 to 18, wherein the levelling mechanism is substantially concealed within the lifting arm.

19. A levelling mechanism for a lifting arm of a skid-steer loader or similar vehicle, the levelling mechanism being substantially as hereinbefore described with reference to Figs. 7 and 8 of the accompanying drawings. A hydraulically driven vehicle substantially as hereinbefore described with reference to the accompanying drawings