GB2239637A - Agricultural vehicle, eg. for cultivation or cutting grass - Google Patents

Abstract

The vehicle comprises: (a) a drive section comprising a rectangular frame (11) having ground wheels (12) driven by engine (15) and carried by an axle (13) located intermediate the ends of the frame so that the frame can pivot about the axle in the vertical plane; (b) linkage means (21,19) for connecting the frame (11) to a forward attachment member (2), eg grass-cutter, and a rearward member (3) for the operator for relative movement in the vertical plane between the frame and the forward and rearward members (2), (3), whereby the chassis of the tractor unit can articulate in the vertical plane. The rearward member (3) preferably also carries means eg crossed cables or hydraulic rams for steering the tractor unit. The engine (15) may drive the wheels (12) through a hydrostatic gearbox (14). The grasscutter may be driven by belt from an engine-driven pulley (16). The vehicle is highly manoevrable, can accommodate unevenness in the ground and is well balanced. <IMAGE>

Description

TITLE: AGRICULTURAL APPARATUS The present invention relates to an agricultural apparatus, notably to a tractor unit for transporting attachments over the ground.

BACKGROUND TO THE INVENTION: Many forms of mini-tractor have been proposed for use in the cultivation and cutting of grass and other areas.

However, none of these is wholly satisfactory. Thus, for example, a conventional mini-tractor based on a rigid chassis construction with an under-slung mower attachment is usually not very maneouvrable and cannot cut grass right to the edge of right angled or other sharp corners, nor can they cut the grass closely around small areas due to their comparatively large turning circle. Although a pedestrian controlled mower can usually be manoeuvred into and within such confined spaces, they lose much of their manoeuvrability when a ride on seat is attached to the rear thereof for the operator to ride on when large areas are to be mown.

It has been proposed to form a tractor with a vertical pivot joint in the chassis so as to allow the tractor chassis to articulate horizontally about that pivot and thus aid manoeuvring of the tractor. It has also been proposed to mount the mower deck or other attachments at the front of such a tractor so that the tractor can cut grass closer to the edge of sharp angled corners and also so that much of the load of the attachment is carried by the front drive wheels of the tractor, thus aiding drive grip on the ground. However, in order to prevent the tractor from tipping forward when the operator gets off the tractor, there must remain sufficient weight over the rear wheels to stabilise the tractor, and this would normally represent a proportionate reduction in the load over the drive wheels.

In order to accommodate uneveness in the ground to be mown, it has also been proposed to mount the attachment so that it can rise and fall or pivot to a limited extent on its mounting to reduce the risk that it will dig into the ground where a sharp change of the ground level is encountered. However, such float in the mounting of the attachment is limited so that the attachment is retained substantially in the same horizontal orientation to the longitudinal axis of the tractor chassis at all times.

I have devised a form of tractor unit and attachment linkage which reduces these problems.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a chassis for a tractor unit for the transport of an attachment over the ground, characterised in that the chassis comprises: a. a drive section comprising a generally horizontal axial beam member having one or more ground engaging drive wheels carried by a transverse axle located intermediate the ends of the beam and about whose horizontal axis the beam member is adapted to pivot in the vertical plane, said drive section also preferably being provided with a motor means for driving said drive wheels; b. linkage means for connecting the beam member to a forward member and a rearward member, which linkage means are adapted to permit relative movement in the vertical plane, preferably by rotation about a horizontal transverse axis, between the beam member and the forward and rearward members, preferably such linkage means are located one at or adjacent the pivot point of the beam member about the transverse axle and the other located at or adjacent the forward end of the beam member; and c. a rearward member adapted to support an operator of the tractor unit and linked to the beam member by means of said linkage means, preferably located at or adjacent the pivot point of the said beam member, whereby the rearward member can move relative to the beam member so that the chassis of the tractor unit can articulate in the vertical plane, the rearward member preferably also carrying means for steering the tractor unit.

The tractor unit preferably also comprises an attachment, for example a rotary mower deck or a grass cutting cylinder mower attachment, mounted as the forward member carried by the beam member by means of the forward linkage means.

Where the forward attachment is to be driven by the motor of the chassis, it is preferred that the drive be by means of a belt drive from the motor to an intermediate driven shaft whose axis of rotation is substantially co-incident with the axis of the horizontal axis of pivot of the forward attachment at the linkage means. In this way, as the attachment pivots about the horizontal axis of its mounting, the geometry of the drive belt path remains substantially constant and there is little or no affect on the tension in the drive belts.

By forming the chassis of the tractor unit with the two linkage means permitting relative vertical movement between the central drive unit beam member and the rearward and forward members, the tractor chassis and the forward attachment can more readily accommodate changes in the ground levels or slope than a conventional tractor unit having a horizontally rigid chassis. Since the forward member is attached by means which allow it to pivot or move vertically with respect to the beam member, not only can it follow the contours of the ground more independently of the tractor unit than hitherto, but such a mounting allows the beam member to be tilted to allow the attachment to remain on the ground for engaging or disengaging the linkage to the beam member. This greatly assists mounting and demounting the attachment.

By suitable selection of the location of the linkage points for the forward and rearward members, the beam member can float with respect to those members without significantly affecting the orientation of those members as it pivots about the transverse axle, thus further assisting the operation and ground following characteristics of the chassis of the tractor unit of the invention.

The beam member can be of any suitable form, for example a box girder or other frame, carrying the tractor unit motor mounted on it and being supported by ground wheels carried by a transverse axle also carried by the beam member. In a preferred form, the beam member comprises a horizontal rectangular frame made from box or U girders and carrying the motor unit, the gearbox, battery and drive wheels mounted thereon in any suitable manner. It is preferred that the motor unit incorporate or drive means for generating high pressure hydraulic fluid for operation of attachments and other components of the tractor unit, for example hydraulic rams for tipping a grass box, etc. It is also preferred that the motor, the battery and other items carried by the beam member are located adjacent but to the rear of the transverse axle about which the beam member pivots and that the gearbox, for example an hydrostatic gearbox, carry the transverse axale projecting to each side thereof. In this way the beam unit has a slight nose down weight, typically 5 to 20 Kgs, when the most commonly used attachment is mounted upon the forward linkage means. As a result, the beam member is substantially free to float about its axis point on the transverse axle. If desired, the beam member can be provided with one or more adjustable weights to achieve the desired nose weight when various attachments are in place or to provide the necessary nose weight when no attachment is carried by the tractor unit.

Alternatively or in addition, the beam member can be provided with counterbalance springs, hydraulic rams or gas struts in the linkage means to the rearward member to assist the balance of the beam member and/or to restrict excessive float of the beam member with respect to either or both of the forward and rearward members.

The beam member is adapted to pivot about the transverse axle which carries the ground engaging drive wheels. It is preferred that the transverse axle be a single axle carrying a pair of wheels, one located to each side of the longitudinal axis of the beam member to impart lateral stability to the tractor unit. However, the axle could be in the form of two axially opposed stub axles rather than a single axle extending across the axis of the beam member.

The ground wheels are preferably driven mechanically from the motor unit by a conventional gear, hydrostatic or chain drive. However, it is also within the scope of the present invention for each ground wheel to be driven independently by hydraulic means, in which case the tractor unit steering can be achieved by varying the relative speed of the hydraulic motors driving the wheels.

It is preferred that the beam member be supported by two ground wheels carried by the one transverse axle to provide lateral stability to the chassis. However, where the rearward unit is carried by two wheels, this may supply the lateral stability to the tractor unit, in which case the beam member may be supported by a single ground wheel.

However, the beam member carries most of its weight generally evenly balanced over the drive wheel axle and the floating action of the beam member transfers little or none of this weight to the forward or rearward members. It is therefore preferred to maximise the available drive grip through the drive wheels carried by the beam member and that two or more drive wheels support the beam member. If desired, the drive wheels could be in the form of caterpillar or other tracked drive systems to further improve the drive grip.

The beam member can also carry other features required for the operation of the tractor unit, for example means for driving attachments carried by the beam member, eg. a drive pulley for providing a belt drive from the motor unit to the forward attachment, and hydraulic hose outlets with snap or other removable fasteners for connecting to the removable attachments and/or the rearward member described below. It is preferred that the drive pulley for the belt drive to the forward attachment be located below the horizontal pivot line of the attachment at the forward linkage so that the operation of the forward linkage tensions the drive belt from the drive pulley to the intermediate drive shaft described above for the attachment when the linkage mechanism is operated as described below.

The rearward member acts to support an operator of the tractor unit independently of the beam member. It is preferred that the rearward member also carry the means by which the line of travel of the tractor unit can be varied.

Typically, this will take the form of one or more ground support wheels carried by the rearward member by a support which pivots about a vertical axis to steer the tractor unit. The weight of the rearward member and the operator is preferably carried substantially completely by the support wheel(s) and, by virtue of the form of linkage between the beam and rearward members, not by the beam member. In a preferred design, the rearward member comprises a suitable box or girder frame carrying a seat or saddle for the operator and supported by a single ground wheel carried by a vertical tubular member which can be rotated by means of a conventional crossed wire mechanism, hydraulic rams or other means operated from the steering wheel, handlebar or other steering means.

The rearward member can be provided with other features to enhance the utility or operation of the tractor unit.

Thus, it will usually be preferred that the rearward member carry a control panel for the operation of the hydraulic components of the tractor unit and a steering wheel, joystick, handlebars or other means for controlling the steering mechanism; and can be provided with a ball or other type of hitch whereby other attachments can be pulled by the tractor unit.

The beam member is connected to the rearward member by a linkage which allows the two members to articulate in the vertical plane relative to one another. The linkage can thus be a simple horizontal pivot pin connecting the two members. However, it is also within the scope of the invention to connect the two members by means of a linkage which allows one member to move vertically with respect to or within the other. Thus, the linkage could be through a series of arms or levers linked through horizontal pivot pins or the like. Alternatively, the members at the linkage point can take the form of two horizontal channel members journalled one within the other to allow one member to rise and fall within the other.In a further form of linkage, two upright tubular members are journalled upon one another to provide the freedom of relative vertical movement whilst also allowing pivotting about the axes of the tubular members to enable the tractor unit to articulate in the horizontal plane as well as the vertical plane. If desired, the linkage can incorporate hydraulic rams, springs or other means for damping the relative movement of the beam and rearward members about the linkage and/or to provide restraint against excessive relative movement and/or to provide for relative movement about a vertical axis so that the chassis can be steered.

Typically, the linkage will allow relative vertical articulation of between + 5 and + 250'about a straight line linkage. If desired means, for example an hydraulic ram, can be provided to lock the rearward and beam members so that the articulation is restricted or prevented, for example when the tractor unit is to be operated without any forward member attached or it is desired to depress the front end of the beam member for the attachment of a forward member resting on the ground, as described below.

Whilst the rearward member can be attached by a linkage located at or adjacent the rearward end of the beam member, this may cause excessive movement of the rearward member as the beam member pivots about its supporting axle. It is therefore preferred that the linkage between the rearward member and the beam member be located at or closely adjacent the pivot point of the beam member, for example immediately above the pivot point of the beam member. This can be achieved, for example, by extending the rearward member by lateral arms extending alongside the rear portion of the beam member and connected by suitable pivot pins to the side wall of the beam member at a point immediately above the axis of the transverse axle. The lateral extension arms can also carry brake pedals, gear selectors and other controls to be operated by the operator and connected by suitable wire or hydraulic linkages to the corresponding operative elements carried by the beam member.

The beam member carries at its forward end the attachment to be carried over the ground secured to the beam member by a forward linkage means. This attachment can be selected from a wide range of implements, for example a suction or rotary brush sweeper, a scraper blade, or a grass cutting rotary blade deck or cylinder cutter attachment. For convenience, the invention will be described in terms of a cylinder type grass cutting attachment.

The grass cutting attachment typically comprises two side frame members carrying the cylinder transversely between them with a back frame by which the attachment is secured to the beam member of the tractor unit. The attachment can also carry a grass box or the like into which grass cuttings are thrown as the cylinder rotates. Preferably, such a grass box is provided with means, for example a manual lever or hydraulic ram, whereby the box can be raised to empty the box by an overhand type of action so that the grass can be tipped onto a heap when the box is full or a suitable emptying point has been reached. Any suitable construction for the grass cutting and grass box attachments may be used.

The attachment is secured to the front end of the beam member by a linkage which permits the attachment to move vertically with respect to the beam member, for example by pivotting about a horizontal axis at or adjacent the linkage point. If desired, the linkage can incorporate a measure of vertical float in addition. Thus, the attachment can be secured by means of latches carried at the forward ends of the each side of the beam member and which engage a cross bar carried at the rear of the attachment. However, it is particularly preferred that the linkage not only secures the attachment to the beam member but also moves the attachment axially forward so that the operation of the latch also tensions a belt drive between the attachment and the tractor unit.Thus, the linkage can be by means of a pivotting arm carrying a socket or hook which engages with a transverse bar or co-operating sockets on the attachment. As the arms are rotated about their horizontal axes, the socket or hook is carried axially forward. If desired, the sockets or hooks can incorporate a locking latch, pin or the like which traps the bar or sockets of the attachment in the socket or hook of the arm.

Such a locking mechanism can be manually operated once the arms are fully deployed or can be interlinked with the movement of the arms so that they automatically operate as the arms move. Many suitable forms of such a linkage and locking mechanism can be devised for present use.

Preferably, the operation of the arms and the locking mechanism is achieved by means of the hydraulic system of the tractor unit.

As indicated above, it is also preferred that the drive from the motor on the beam member to the forward attachment be via an intermediate drive shaft whose axis of rotation is substantially co-incident with the axis of the horizontal cross bar with which the front lnkage mechanism engages. In this way, the drive geometry between the motor and the intermediate drive shaft remains substantially constant when the forward attachment pivots about the cross bar, for example as it tilts to follow a rise or fall in the ground surface. This ensures that the drive belt tension remains substantially constant. If this is not done, other mechanisms, for example splines drives or spring biassed shaft mounting would have to be provided to accommodate changes in the drive geometry.

The pivotting arm type of linkage offers the further advantage that it can be used to pick up and secure an attachment which rests of the ground, thus reducing the need for an operator to man handle the attachment and lift it off the ground for attaching it to the tractor unit.

The tractor unit chassis of the invention can incorporate other features which enhance the utility and ease of operation of the unit, for example lights for night driving, a cab for the operator and so on. These can be of any suitable construction having regard to the vertical articulation of the various section of the chassis of the tractor unit and its attachments.

DESCRIPTION OF THE DRAWINGS: The invention will now be described by way of illustration only with respect to the accompanying drawings in which Figure 1 is a diagrammatic side elevation of the chassis of the tractor unit with a cylinder grass cutting attachment mounted at its forward end; Figure 2 is a diagrammatic plan view from above of the chassis of the tractor unit of Figure 1; and Figure 3 is a detailed diagrammatic side view of the front linkages for the grass cutting attachment.

DESCRIPTION OF THE PREFERRED EMBODIMENT: The chassis of the tractor unit comprises a central beam member 1, the grass cutting forward attachment 2 and the rear member 3 upon which an operator sits when driving the tractor unit.

The beam member comprises a rectangular frame 11 suported on two ground wheels 12 by means of a transverse axle 13 driven through a suitable gearbox 14 from a petrol or diesel engine 15. The gearbox 14 preferably is of the hydrostatic type from which a transverse axle projects at each side to provide the transverse axle 13. It is preferred that the engine 15 also drive a T gear box to provide one or more a drive pulleys 16 to drive a belt drive to the attachment 2. The pulley 16 is located below the level of the front linkage means described below so that operation of the linkage acts to tension the drive belt carried by pulley 16.

An hydraulic pump 17 driven from the engine 15 is also provided to drive hydraulic rams and the like for operating the tractor unit.

The engine, gearbox and other components are located on the beam member frame 11 so that the beam member is substantially balanced about the transverse axle 13 when the attachment 2 is in position.

The rear member 3 comprises a second rectangular frame 31 which carries a saddle type seat for the operator and is supported by a single or twin ground wheel 32 carried on a vertical tubular support so that the wheel can be steered by means of a crossed cable link or one or more hydraulic rams 33 operated in response to a steering yoke or wheel 18 carried on a control panel on the rearward member. The frame 31 carries a lateral extension arm 34 at each side thereof which extends axially forward alongside the sides of the beam member frame 11. The arms 34 can carry foot rests, brake pedals and other items conventionally required for the operation of a tractor unit.

The forward ends of the arms 34 are attached to the frame 11 by transverse pivot pins 19 so that the arms can pivot vertically with respect to the frame 11. If desired, tension or compression springs, gas struts or other means 35 can be provided for damping the pivotting of arms 34 with respect to frame 11. It is also preferred to provide one or more hydraulic rams or mechanical linkages to regulate the pivotting of the arms 34 with respect to the frame 11. These means 36 can be such as will lock arms 34 to frame 11 in any desired orientation or move arms 34 into a desired orientation and retain them in that orientation, for example as when the means 36 are double acting hydraulic rams.

The attachment 2 is secured to the forward end of frame 11 by means of the overcentre or cammed arms 21 which pivot forwardly about the transverse pivot pins 22. The arms carry hooks 23 which engage with a transverse bar or bars 24 carried at the rear of the frame 25 of the attachment 2.

The arms 21 also carry or co-operate with latches 26 which secure the bar(s) 24 within the jaws of the hooks 23. The pivotting of the arms causes the hooks 23 to engage the bar(s) 24 and to lift and carry the attachment forward until the latches 26 are fully engaged. The arms 21 can be moved manually or can be moved by a suitable hydraulic ram mechanism (not shown).

The action of the arms in engaging the attachment lifts the attachment vertically. Thus, the attachment can be set on the ground and the tractor unit driven up to it with the arms 21 in the lowered position. The operation of the arms then secures the attachment to the tractor unit and lifts the attachment clear of the ground. By suitable sizing of the arms and their throw, the attachment can be lifted to the required operating height without the need for the operator to lift the attachment.

Where the attachment is to be driven by a belt drive from the engine 15 on frame 11, this may be by means of a belt driven from pulley 16. As the attachment is lifted by arms 21, it is also carried axially forward and this movement will usually be sufficient to tension the belt drive. As stated above, the belt drive from pulley 16 drives an intermediate shaft which can be provided as the cross bar 24 or a sleeve member carried on the bar 24. In this way, the drive geometry between pulley 16 and the intermediate drive shaft remains constant once the attachment 2 is secured in position and the latches on the lifting hooks 21 engaged.

I believe that this form of means for connecting an atachment to a tractor unit is novel and the invention also provides a means for connecting an attachment to the frame of a tractor unit having means for providing a belt drive to operate the attachment, which connecting means comprises one or more arms having securing means adapted to engage a component of the attachment and to secure that component to the arms, characterised in that the arms are adapted to move relative to the frame of the tractor unit whereby the securing means move both vertically and horizontally with respect to the frame.

Preferably, the arms are pivotted about a point intermediate their centre point and the opposed end to that carrying the securing means. Preferably, also, the component by which the attachment engages the securing means is a transverse cross bar or other pivotable mounting member incorporating a drive shaft whose axis of rotation is substantially co-incident with the pivot axis of the transverse member.

The attachment 2 can carry other features to enhance its utility, for example a grass box 27 having its open face directed rearwardly so as to receive grass cuttings thrown forward by the rotation of the cutting blades or cylinder of the attachment. Preferably, the grass box is pivotally mounted at its forward upper corners upon arms 28 extending forward and upward from the frame of the attachment. The grass box can be pivotted about the pivot points anticlockwise in the configuration shown in Figure 3 so that the box executes an overarm type of action to discharge its contents. This pivotting is conveniently achieved by providing the piston rod of the hydraulic ram with a toothed or ratchet axial surface which engages with a sprocket carried on the pivot pin by which the grass box is pivotably attached to arm 28. As the ram is operated, the ratchet teeth will cause the grass box to pivot about its pivot mounting to throw the contents of the grass box forward of the attachment in an overarm type of action.

Such an action facilitates discharge of the grass cuttings onto a pile ahead of the attachment but whilst under the visual supervision of the operator. Where the operation of the grass discharge is carried out using hydraulic rams, the operator need not demount from the tractor unit until the grass cutting is completed and can then lower the attachment arms 21 to enable the attachment to be removed without having to lift the attachment manually.

Claims (14)

CLAIMS:

1. A chassis for a tractor unit for the transport of an attachment over the ground, characterised in that the chassis comprises: a. a drive section comprising a generally horizontal axial beam member having one or more ground engaging drive wheels carried by a transverse axle located intermediate the ends of the beam and about whose horizontal axis the beam member is adapted to pivot in the vertical plane, said drive section also preferably being provided with a motor means for driving said drive wheels; b. linkage means for connecting the beam member to a forward member and a rearward member, which linkage means are adapted to permit relative movement in the vertical plane between the beam member and the forward and rearward members; and c. a rearward member adapted to support an operator of the tractor unit and linked to the beam member by means of said linkage means, whereby the rearward member can move relative to the beam member so that the chassis of the tractor unit can articulate in the vertical plane, the rearward member preferably also carrying means for steering the tractor unit.

2. A chassis as claimed in claim 1 wherein the linkage means permit rotation about a horizontal transverse axis,

3. A chassis as claimed in either of claims 1 or 2, wherein the linkage means for the rearward member is located at or adjacent the pivot point of the said beam member.

4. A chassis as claimed in either of claims 1 or 2, wherein two linkage means are provided, one located at or adjacent the pivot point of the beam member about the transverse axle and the other located at or adjacent the forward end of the beam member.

5. A chassis as claimed in any one of the preceding claims wherein the beam member carries an attachment selected from a rotary mower deck. or a grass cutting cylinder mower attachment, mounted as the forward member carried by the beam member by means of the forward linkage means.

6. A chassis as claimed in any one of the preceding claims, wherein the beam member carries a motor unit for propelling the tractor unit located adjacent to but to the rear of the pivot point of the beam member and a gearbox drive transmission between the motor and the ground wheels located upon the transverse axle, whereby the forward end down bias of the beam member having the forward member attached thereto is at least in part counterbalanced.

7. A chassis as claimed in any one of the preceding claims, wherein the beam member is free to float about the transverse axle without significantly affecting the orientation of the rearward member.

8. A chassis as claimed in any one of the preceding claims, wherein the rearward member is provided with members extending axially to either side of the beam member and attached to the beam member at or adjacent the pivot point thereof by transverse pivot linkages to provide the said linkage means between the beam member and the rearward member.

9. A chassis as claimed in any one of the preceding claims, wherein the linkage between the beam member and the rearward member allows relative pivotting of the member about a horizontal axis through from + 5 to 250.

10. A chassis as claimed in any one of the preceding claims, wherein there is provided a belt drive for the forward member and the front linkage means for the mounting thereof upon the beam member incorporates means for moving the attachment both vertically and horizontally when actuating the linkage means.

11. A chassis as claimed in claim 10, wherein the front linkage means comprises a hook member adapted to provide a pivot mounting for the forward member, said hook member pivotting about a transverse pivot whereby the open end of the hook member follows a rising and forward movement as the hook member engages the forward member, and the drive between the motor carried by the beam member and the forward attachment is via an intermediate drive shaft whose axis of rotation is substantially co-incident with the pivot axis of the said pivot mounting.

12. A chassis as claimed in any one of the preceding claims, wherein the forward member comprises a cylinder mower attachment carrying at the forward end thereof a grass box adapted to be emptied by an over arm action.

13. A chassis as claimed in claim 1 and as substantially hereinbefore described.

14. A chassis substantially as hereinbefore described with respect to and as shown in the accompanying drawings.