CA1054528A - Tractor - Google Patents

Abstract

Abstract of the Disclosure An agricultural or other tractor is disclosed of the kind which has an engine and front and rear ground wheels. The engine is located in advance of the front wheels with respect to the intended direction of forward travel of the tractor, the front and rear wheels are relatively pivotable about a substantially vertical axis that is positioned between them, and a lifting device is provided at substantially the rear of the tractor with respect to the direction of travel.

Description

~0s4s28 This invention relates to agricultural and other tractors, such tractors being of the kind which comprise an engine and front and rear ground wheels. The term "tractor" is to be interpreted as including vehicles such as those that are used in civil engineering works and that are intended to be operable on land not provided with roadways or the like.
According to one aspect of the invention, there is provided a tractor comprising an engine, two groups of ground wheels, a frame which comprises at least two portions, said portions being pivotable relative to one another about a substantially vertical axis, wherein a first portion supports the engine and a torque converter coupled to the output of the engine and the second portion supports a console comprising a driving seat, a steering wheel, steering and operating controls, the first frame portion being supported by a first group of ground wheels, the second frame portion being supported by the second group of ground wheels, said console being turnable through substantially 180 about a substantially vertical axis relative to said second portion and means provided to retain said console in a position in which a driver occupying said seat faces generally forwardly and alternatively in another position in which said driver faces generally rearwardly of the tractor, coupling means being provided near at least one end of said frame for coupling at least one attachment to the tractor.

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~54S28 For a better understanding of the invention, and to show how the same may be carried into effect, ref-erence will now be made, by way of example, to the ac-companying drawings, in which:-FiguIe 1 is a plan view of an agricultural t~actorin accordance with the invention, Figure 2 is a side elevation of the tractor of Figure 1, Figure 3 is a front elevation as seen in the dir-ection indicated by an arrow III in Figure 2, Figure 4 is a rear elevation as seen in the dir-ection indicated by an arrow IV in Figure 2, Figure 5 is a partial rear elevation, to an en-larged scale, of the tractor of Figures 1 to 4, the tractor being illustrated in operation with one ground wheel in a ploughed furrow, Figure 6 is a part-sectional plan view, to an enlarged scale as compared with Figures 1 to 4, of a rear central region of the tractor of Figures 1 to 5, Figure 7 is a plan view that is similar to Fig-ure 1 but illustrates some modifications to the trac-tor b~ Figures 1 to 6, Figure 8 is a plan view of an alternative agri-cultural tractor constructed in accordance with the invention, and .
Figure 9 is ~ slde elevatlon of the tractor of Figure 8.
' Referring to Figures 1 to 6 of the drawings, 'i those Figures illustrate an agricultural tractor but .!

' :' ' 1~)54528 it is emphasised that this is purely by way of example and that the invention is equally applicable to a tractor that is intended for non-agricultural purposes.
~he tractor has a frame that is generally indicated by the reference 1, said frame 1 comprising a substantial-ly horizontal beam 2 that is substantially parallel to the intended direction of forward travel of the trac-tor that is indicated by an arrow A in ~igures 1 and 2 of the drawlngs. ~he rear end of the ~rame beam 2 with respect to the direction A is secured to the housing of a torque converter 3 whose rear, in turn, is secured to the housing 4 of a differential. ~he output shafts of the differential carry rear driven ground wheels 5 whose arrangement will be described in greater detail below. Smaller front ground wheels 6 are indirectly connected to the frame beam 2 near the leading end of that frame beam in a manner which will also be described in greater detall below. ~he tractor has an engine 7 which, in the example that is being described, is an internal combustion engine rated at not less than substantially 100 horsepower~ said engine 7 being mounted on top of the frame beam 2 at a location in front of the torque converter ~ so as to lie at a horizontal level above that of the tops of the front ground wheels 6 with at least part of the engine as far advanced in the direc-tion A as are the front ground wheels 6.
A hydraulic mechanism 8 which operates a rear-mounted three-point lifting device or hitch 9 of the tractor is arranBed on top of the differential housing _ 4 -::
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-4 at substantially the rear of that housing with respect to the directlon A. The lifting device or hitch 9 com-prises two upper arms 10 that are located along~ide one another in horizontally spaced apart relationship, the arms 10 being turnable upwardly and downwardly about the aligned axes of corresponding shafts 11. ~he aligned axes of the two shafts 11 extend substantially horizon-tally perpendicular to the directlon A and are turnable by the hydraulic mechanism 8, in a manner that is known .
per se, to raise or lower the upper arms ~0 as may be required. The free rearmost ends of the upper arms 10 are pivotally connected to the upper ends of correspond-ing rods 12, the lower ends of those rods being pivot-ally connected, in turn, to lugs that are located bet-ween the ends of corresponding lower lifting links 13.
In the embodiment which i5 being described, said lugs are disposed substantially midway along the lengths of the two lower lifting li~ks 13. ~he leading ends of the links 13, with respect to the direction A, are turnably connected by substan~ially horizontally al-igned pivot pins 14 to lugs that are carried by the differential housing 4, the axis that is defined by the pivot pins 14 being substantially perpendicular to the direction A.
~ he to~ of a housing o~ the hydraulic mechan-ism 8 carries a pair o~ substantially symmetrically identical supports 15 which supports extend obli~uely upwardly and rearwardly away from said housing to term-inate at a height above ground level which is substan- - --~545Z8 tially equal in magnitude to ~he diameter of one of the rear driven ground wheels 5. ~he upper rear ends of the two supports 15 are rigidly interconnected by a horizon-tally disposed beam 16 which extends substantially perpendicular to the direction A throughout nearly the whole width of the tractor (see Fig~e 1). As seen in plan view (Figure 1), the beam 16 is located behind the common axis of rotation of the rear driven ground wheels 5, said beam 16 supporting a platform 17 that extends forwardly therefrom relative to the direction A. ~he platform 17 forms part of the bot-tom of a driving cabin 18. A rear portion of the :
platform 17 is substantially horizontally disposed but, at a location which is just in front of the common axis of rotation of the rear ground wheels 5 with respect to the direction A, the platform is bent over obliquely downwardly and, at its front, forms a lower cabin floor portion 19 at the foot of opposite side doors 20 of the cabin. A front wall 21 of the driving cabin 18 has a large central window (Figure 3) and is located immediately in front of the leading hi~ged edges of the two side doors 20, those doors 20 also being provided with windows throughout most of their respective areas. Access ladders 22 that each comprise fGur rungs are arranged beneath the two side doors 20 wlth the upper rungs thereof at substantially the level of the lower cabin floor portion 19. ~he upper edge of the front wall 21 of the cabin 18 is connected to a cabin roof 23 and the .

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rear edge of said cabin roof is connected to a rearwall 24 of the cabin. ~he side doors 20 of the cabin 18 are located in side w~lls 25 thereof and it will be noted from the drawings that the rear wall 24 and side walls 25, like the side doors 20 and the front wall 21, are provided with windows throughout the greater parts of their ~espective areas.
A frame 26 is located inside the driving cabin 18 and carries a driving seat 27, a steering wheel 28 and other control members for the operation of the tractor. lhe platform 17 carries an upright pivot 29 and the frame 26, together with the parts which it carries, is turnable around the pivot 29 on the plat-form 17 between the position illustrated in Figure 2 of the drawings in which a person occupying the seat 27 will face forwardly in the direction A and an al-ternative position, that is turned through 180 about the axis of the pivot 29, the alternative position being such that a person occupying the seat 27 will face rearwardly with respect to the direction A and towards the window in the rear wall 24 of the cabin 18. Means that is not illustrated in the drawings is provided to enable the frame 26 to be retained in either of the two alternative postions about the pivot 29 that have just been described. As seen in plan view, the whole of the frame 26 i5 located behind the lower cabin floor portion 19, with respect to the directio~
A, in either of the two alternative positions of use thereof. ~he driving cabin 18 has a width which is ~ -_ 7 .

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preferably not less than 1.5 metre~ a~d not ~reater than 1.8 metres and, with such a transverse dimension, that part of the interior of the cabin 18 that is dis-posed between the side doors 20 is sufficient to accom-modate a person standi~g upright where the view of the ~river occupying the seat 27 will not be impeded in substantially the direction A to any disadvantageous extent. ~he distance between the lower cabin floor portion 19 and the cabin ~oof 23 is great enough to enable anyone who is not unusually tall to stand without stopping and, if such a person stands side-ways with respect to the direction A, their inter-ference with the driver's view in that direction will :~
be at a minimum. ~he driving seat 27 is located wholly above the level of the tops af the rear driven ground wheels 5 and the lower cabin floor portion 19 is loca-ted immediately abo~e the top of the differential hous-ing 4, bhe latter being spaced from ground level ~y a distance which is substantially 75% of the diameter of one of the rear driven ~round wheels 5.
~here is, in fact, a row of four of the rear driven ground wheels 5 which are individually designa-:d ted in the drawings by the references 30, 31, 32 and 33. ~he four wheels 30 to 33 are arranged in two pairs that are disposed at opposite sides of a vertical plane of substantial symmetry of the tractor which extends in the direction A~ ~he four rear wheels 30 to 33 all form part of the original equipment of the tractor~ that ~:
is to say, none of them is furnished as an "optional extra".

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; ' . , 1 ~' ' , ' ' ~)S45Z8 The pair of wheels 30 and 31 that is located at one side of the imaginary plane of substantial symmetry of the tractor that has been referred to above has the two wheels rigldly secured to one another and the same is true of the two wheels 32 and ~3 of the pair located at the opposite side of the imaginary plane. Due to the provision of the differential which will be described in greater detail below, the pair of wheels 30/31 or 32/33 that is at the outer convex side of a bend negotiated by the tractor during its travel can rotate at a faster speed than the other pair disposed at the inner concave side of that bend. The overall width o$ the row of four wheels 30 to 33 in a horizontal direction that is substantial- , ly perpendicular to the direction A is preferably not greater than 3.0 metres and, in the embodiment which is being described, said width has a ma~nitude of sub-stantially 2.5 metreS. ~ach of the wheels 30 to 33 has a pneu,m,atic tyre whose tread width in the same dlr-ection as that which has just been mentioned is prefer-ably not less than 35 centimetres and not more than 50 centimetres, a tread width of substantially 45 centi-metres being adva~tageous. lhe spacing between the tyres q$ the wheels 30 and 31 of onç pair and between the tyres of the wheels 32 and 33 of the other pair is preferably substantially 15 centimetres. ~he distance between the pneumatic tyres of the two inner wheels 31 and 32 of the two pairs should not be more than 50 centimetres and a magnitude of between 20 cen~imetres and 40 centimetres inclusive is preferred. In the :

~.-~OS45Z8 embodiment which is being described, the distance inquestio~ is substantially 40 centimetres. ~ach of the four wheels 30 to 33 has an overall diameter which should not be less than 1 metre and which is advantage-ously ~etween 1.4 and 1,8 metres. In the embodiment which is bein~ described, each of the wheels 30 to 33 has an overall diameter of substantially 1.5 metres.
It will be seen from Figure 2 of the drawings that the driving seat 27 in the cabin 18 is located substantial-ly vertically above the common axis of rotation of the four wheels 30 to 33.
As seen in plan view (Figures 1 and 6), the width of the frame 1 varies significantly lengthwise therealong~ ~he parts thereof that are located in front of the rear driven ground wheels 5 (said parts comprising the beam 2, the torque converter 3, the engine 7 and cover plates and the like 34 therefor) have a width that is substantially the same as the distance between a vertical plane of symmetry of the wheel 31 that extends in the direction A and a similar plane in respect of the wheel 32, The parts of bhe frame 1 that are located tq the rear of the torque converter 3, with respect to the direction A, are of significant-ly less width than are the parts disposed in front of the differential housing 4, the latter ~eing the princi-pal or only component of the parts now under considera-tion. ~he width of the rear parts of the frame 1 is between substantially 30 and substantially 45 centimebres inclusive and a width of substantially 35 centimetres 10545;Z8 is preferred so that said parts can fit, as illustrated in the drawings, between the rear wheels 31 and 32 with sufficient worki~g clearance from those wheels.
Figure 6 of the drawings shows that the cover plates or the like 34 for the torque converter 3 and the engine 7 are located, together with said torque converter 3 and engine 7, in front of bhe foremost extremities of the rear wheels 3~ and 32 with respect to the direction A.
It is noted that the term "torque converter" is used in a generic sense and is intended to include within its scope such a mechanism as a manually changeable gear box. The cover plates or ~ like 34 are closer to one another than in the part o~ the .frame 1 that has just been discussed in thç part of the frame that is di~sed between the rear wheels 31 and 32, the spacing therebetween beco~ing narrower fro~ a region of the frame that is located approximately in re~ister ~as seen in plan vieW - ~igure 6) with the foremost ~ -extremiti~s of the wheels 31 and 32 relative to the direction At The cover plates or the like 34 supp~rt, betweqn the wheels 31 and 32, substantial~y harizo~tal-ly aligned bearings 35 an~ 36 that are spaced aparb from one another in the direction A. ~he bearings 35 and 36 rotatabl~ support an output or dFivi~g s~aft 37 of the torque converter 3, the shaft 37 carrying, immediately behi~d the rear bearing 36, a bevei pinio~
3a. ~he teeth of the pinion 38 are in driving mesh with those of a c~own wheel 3~, the crown wheel 39 being rigid with a rotatable houæing 40 in which sub-- '11 -, .

1~)5452~
stantially hori~on-tally aligned output or half shafts 41 and 42 have their inner ends rotatably journalled, ~he inner ends of the two shafts 41 and 42 carry, in-side the housing 40, corresponding bevel pinions 43 and 44, the teeth of both those pinions 43 and 44 being in mesh with the teeth of smaller bevel pinions 45 and 46 that are rotatably mounted in the housing 40, bet-ween the pinions 43 and 44, so as to be capable of revolving about a common axis which is rotatably dis-placeable with the housing but which is always perpen-dicular to the axis of rotation of the output or half shafts 41 and 42. It will be realised from the description that has just been given and from Figure 6, in particular, of the drawings that the differential is of generally known construction.
The shaft 47 extends substantially horizon-tally beneath the output or driving shaft 37 in sub-btantially parallel relationshi~ with that shaft, said shaft 47 being rotatably supported by bearings at appropriate locations in the differential housing 4. ~he shaft 47 projects from the rear of the hous-ing 4 ~o form a rear power ~ake-off shaft of the trac-tor at which point it is splined or otherwise keyed to enable it to transmit-;drive to the working parbs of various rear-mounted tools and implements. ~he power take-off shaft 47 is driven from the output side of the tQrque converter 3 and its speed of rotation rel-ative to that of the engine 7 is therefore dependent upon the gear ratio selected at any p~rticular time.

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It should be noted that it is possible for the shaft 47 to be driven directly from the engine 7 in which case its speed of rotation at any particular time will be the same as that of the output shaft of the engine 7. ~he differential housing 4 is formed with substan-tially symme~rical lateral projections 48 and 49 whase centres are substantially coincident with the cammon longitudinal axis (axis of rotation) of the shafts 41 and 42. Ihe projections 48 and 49 accommodate large substantially horizontal bearings 50 and 51 for inter-medi~ regions of the shafts 41 and 42. Projections 48 and 49 have flanges at the inner ends of gently outwardly tapering axle supports 52 and 53 rigidly secured to them and it will ~e seen from ~igure 6 of the drawings that outer end regions of the two axle supports 52 and 53 receive further substantially hari zont~l bearings 54 for corresponding regians of the $h~fts 42 a~d 41. ~he axle supports 52 and 53 are o~ hollow canstructian and the output or half shafts 41 and 42 which thçy rotatably support, with the ai~
of the bearings 50/51 and 54, have circular discs 55 and 56 rigidly secured to the~ in such a way that the genqral planes af the discs 55 and 56 are perpendic~
ular to the common longitudinal axis of ratation of the two shafts 41 and 42. It will be noted that the rear wheels 31 and 3~ a~e arrnged around the axle supports 52 and 53 respectively, said wheels 31 and 32 having hub portions 57 and 58 which are dispased at the sides of those wheels remate from the differ-:

~054s28 ential housing 4 and which are releasably secured tothe corresponding discs 55 and 56 by bolts 59.
~ he described and illustrated construction whereby the portions 57 and 58 of the hubs of the two wheels 31 and 32 project outwardly from the gen-eral planes of ¢orresponding sides of those wheels is a substantially conventional one for tractors and, with commercially available tractor wheels, the per-pendicular distance between the outermost flat sub-stantially annular surface of each hub portion 57 or 58 and the general plane of the neighbouring side of the wheel 31 or 32 concerned is substantially 7.5 centi-metres. In addition to securing the h~b portions 57 and 58 to the discs 55 and 56, the bolts 59 also secure identical, but oppositely facing, hub portions 60 and 61 of the rear whçels 30 and 33 respectively to the twa dlscs 55 and 56, ~s will be evide~t from Figure 6 of the drawings, the substantially flat annular parts of the hub portions 57 and 58 are sandwiched by the bolts 59 between the corresponding parts of the hub portio~S 60 and 61 and the discs 55 and 56 xespectively. ~he axle supports 52 a~d 53 eac~ have an axial length that is substantially the same as the width (thickness) of the pneumatic tyre of one of the wheels 31 or 32. Because of the pro~ecting construction of the portions 57 and 58 of the hubs of the wheels 31 and 32, quite large cavities are formed "inside" those wheels so that the latter, as briefly mentioned above, effectively surround the -. . . . ,. . . , ~

1(~545Z8 corresponding supports 52 and ~3.
A combined towing and scraping member 62 is fastened to the bottom of the differential housin~
4 and has a width which is substantially the same as that of the rear part of the frame 1 which comprises said housing 4. ~he member 62 is of plate-~ike forma-tion and has a leading substantially horizontal portion, ~ -which is rigidly securedto the housing 4, whose length, in the direc-tion A, is substantially the same as that .
of the radius of one of the rear driven ground wheels that are collectively indicated by the reference 5, The member 62 comprises a downwardly and rearwardly in-clined portion which (see Figure 2) commences at a location just in fro~t of the axis of rotation of the wheels 5 with respect to the direction A. ~he rear-most end of the inclined portion is substantially in line with rear regions of the wheels 5 as seen in :
side elevation (~igure 2) and is there bent over up-wardly to form a small subsbantially horizontal por-tion in which a hole 63 (Figure 6) iæ formed Por tow- . .
ing purposes. ~he small substantially horizontal portion of the member 62 in which the hole 63 is :
formed is located at a height above ground level which has a magnitude of between substantially 30%
and sub$tantially 40% of the radius of one of the rear wheels ~. ~he member 62 has downwardly bent-over stiffening rims 64 (~igure 5) along the edges thereof that are generall~ parallel to the direction A and, since the width of said member 62 is substan-- 15 ~ -~S4SZ8 tially the same as that of the housing 4, its two rims 64 are very close to the inner side surfaces of the tyres of the two wheels 31 and 32. The rims 64 of the member 62 thus perform the scraping function of that member because any significant amounts of mud or the like that may adhere temporarily to the sides of the tyres in question will be stripped from those sides as they move past the rims 64. ~he speci-fied ma~nitude of the distance of the rearmost end of the member 62 above the ground sur~ace is such that, should at least one of the tyres of the two wheels 31 and 32 become puncbured or be seriously underinflated, the bulge that will occur in the lowermost region there-of will be clear of contact with the member 62.
~ he lower li~ting links 13 of the lifting de-vice or hitch 9 are disposed above the rearmost end portion af the member 62 (see particularly ~igure 4) and said member 62 thus also affords a lower stop that limits the possible downward movement of the links 13, ~xtreme rearmost ends o~ the two links 13 are bent over outwardly in opposite directions to form substa~tialIy pIate-shaped scrapers 65 that are both disposed substantially hori.ontally perpendicular to the direction A, the outer extremities of said scrap-ers 65 bei~ located substantially in vertical median planes of the tyres of the two wheels 31 a~d 32 thab extend parallel to the direction A, It preferred, the extremities ~$ the scrapers 65 may be located even further apart from on another beyond the median 105~5;28 planes that have just been mentioned. ~he extremities o~ the scrapers 65 carry end plates 66 that are formed with apertures (see Figure 2), said end plates 66 being substantially vertically disposed and substantially par-allel to the direction ~. ~he leading edges of the plate-shaped scrapers 65 are very close to the treads of the tyres of the two wheels 31 and 32 respectively and, in most positions of the lifting device or hitch 9, said leading edges are at a higher horizonbal level than are the corresponding rear edges. It will be ap-preciated that the inclinations of the scrapers 65 to the horizontal will vary in accordance with the angul-ar po~tions of the lower lifting links 13 about the pivot pins 14.
~ he transvqrse supporting beam ~6 carries two elongated and arcuately curved scrapers 67 that are both of channel-shaped cross~section. Each saraper 67 extends generally pçrpendicular to the longitudinal axis of the beam 16 and is located principally in a corresponding one of the two spaces between the wheels 30/31 and 32/33 respectively. The scrapers 67 are orientated downwardly from the beam 16 and the centre of curvature of each arcuately curved scraper is spaced forwardly therefrom with respect to the direction A.
Each scraper 67 is turnable about the axis o~ a corres-ponding pivot Pin 68, said pivot pins 68 being substan-tially horizontally perpendicular to the direction ~
and being mounted near the opposite ends of the beam 16 by support lugs 69. Each pivot pin 68 has a carres-.. ... . . . , . ~ ~
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105452~
ponding coil spring 70 wound around it with said springs 70 arranged in such a way that one end of each of them is fastened to the beam 16 whilst the opposite end thereof is secured to the scraper 67 concerned at a location spaced from the corresponding pin 68. The springs 70 thus tend to maintain the scrapers 67 in predetermined angular positions about the axes of the pins 68 and to return the scrapers 67 to those positions upon di~placement thereof in either direction about the pins 68. Each scraper 67 has a width in a horizontal direction that is perpendicular to the direction A which is a little smaller than is the distance between the relatively facing side surfaces of the pneumatic tyres of the rear wheels 30/31 and ~2/33 respectively. In the embodiment which is being described, the width of each scraper 67 is substantially 12 centimetrqs. As an al-ternative bo the channel-shaped cross-section that is illustrated ~or the scrapers 67, they may each have a I-shaped cross-section.
Braçkets 71 (~igure 3) depend from ~he frame beam 2 at locations near to the leading end of that frame beam and carry a strong horizontal pivot 72 whose axis is substantially hori~zontally parallel to the direction A, said axis being ¢ontained in the aforementi~ned imaginary substantially vertical plane o, sub$tantialy symmetry of the tractor that extends in the direction ~. ~he cen~re of a fr~nt axle beam 73 is rockable a~ou~ the pivot 72 between the brackets 71 and the beam 73 is normally substantially ho~izontally -- 18 - ~

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lOS4528 perpendicular to the direction A. ~he axle beam 73 is freely rockable about the pivot 72 and indirectly carries the front wheels 6. ~here are two pairs 74/75 and 76/77 of the front wheels 6, said two pairs being located substantially symmetrically (when they are dis-posed for straight travel of the tractor) at opposite sides of the imaginary plane of substantial symmetry of the tractor that has been referred to above. The pair 74/75 of front wheels is angularly steerable about the substantially vertical axis of an intervening shaft 78 and the pair of front wheels 76~77 is steerable in the same way about the similarly disposed axis of a shaft 79. ~teering arms 80 and 81 are fastened to the upper ends of the shafts 78 and 79 respectively and ex-tend rearwardly and downwardly (see Figure 2) therefrom in r~arwardly conver~ent (see ~igure 1) relationship. A
track ~od 82 pivotally interconnects the rearmost ends of the two steering arms 80 and 81 in a generally known manner and is operatively coupled to the steerin~ wheel 28 by parts which are not illustrated in the drawings and which it is not necessary to describe for the pur-poses of the present invention ~he lower ends of the two shafts 78 and 79 are fastened to short substantial-ly horizontal housings 83 and 84 respectively, said housings being angularly steerablq with the shafts 78 and 79 and each of them accommodating a corresponding one of the hydraulic motors (not illustrated). Each hydrauiic motor drivqs ones of the corresponding pair of front wheels 74/75 and 76/77, the hydraulic motors - 19 - :

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being supplied with oil or other fluid pressure medium fram a hydraulic pump that is not illustrated ln such a way that they can rotate at dissimilar speeds when, for example ? the tractor is negotiating a bend.
Figure 5 of the drawings illustrates the pair of rear wheels 30/31 at one side of the imaginary sub-stantially vertical plane of substantial symmetry of the tractor that extends in the direction A. It will be seen from Figure 5 that the pneumatic tyres of the two wheels 30 and 31 have different treads. ~he tyre of the outer wheel 30 has obli~ue tread teeth 85 and the tyre of the inner wheel 31 has oblique tread teeth 86 ~ut the radial height of each tooth 86 is between twice and three times that of each tooth 85. Moreover, the regular circumferential distance between the teeth 85 of the tread of the tyre 30 is less than the regular distance between the teeth 86 of the tread of the t~re 31 ? the teeth 86 preferably being spaced apart ~rom one another by substantially twice the distance between immedia~ely neighbouring teeth 85.
Figure 7 of the drawings illustrates a tractor which is basi~ally identical to the one that has already been described above with reference to Figures 1 to 6 of the drawings but in which the arran6ement of the rear driven ground wheels 5 is different. ~he rcw of four ~;
rear wheels 30 to 33 inclusive has an overall width in a direction perpendicular to the direction A of substan-tially 2.0 metres which is convenient for travel along public roads and the like. However, when the tractor ~0545Z~
is to operate in extremely adverse ground conditions, it is advantageous to employ two additional rear wheels 87 and 88 alon~side the rear wheels 30 and ~ respective-ly. The overall width of the row which then comprises six of the wheels 5 is increased to substanti~lly 3.0 metres. Each of the two wheels 87 and 88 has a tyre width (thickness) of substantially 38 centimetres and distances of substantially 12 centimetres are left bet-ween the facing surfaces of the tyres of the wheels 30/
87 and 3~/88 respectively. Once a~ain, in the embodi-ment of Figure 7, the distance between the tyres of the two wheels 31 and 32 that are located at immediate-ly opposite sides of the differential housing 4 is sub-stantially 24 centimetres. Moreover, output or half shafts of the differential again project axi~lly through in-ternal cavities of the wheels 31 and 32 but, in this case, they also pro~ect through internal ~avities of the respectively immediately nçighbouring wheels 30 and 33. ~he additional wheels 87 and 88 at the opposite e~ds of the row are, when fit~ed, secured to the wheels 30 and 3~ in substantially the same manne~ as has alread~ been described with reference to Figure 6 of the drawings for the connections between the wheels 30/31 and 33/32. However, i~ will be ~oted ~hat, to this end, the wheels ~0 and 33 require to be furnished with hub portions that ~re similar to the Portions 57/
58 and 60~61, at both their opposite sides or to be provided with sçp~rate auxiliary hub portions. ~igure 7 illustirates the provision of single front ground wheels 6 at opposite sides of the frame 1 but it is, of course, possible to provide the wheels 6 in pairs as has already been described with reference to ~`igures .~
1 to.~ of the drawings.
In the embodiment of Figure 7, the towing and scraping member 62 is of a different construction to that which has been described above. A rearmost end ..
portion of the member 62 has a scraper 89 rigidly sec-ured to it so as to extend substantially horizontally perpendicular to the direction A. It will be noted from Flgure 7 that the opposite free ends of the scrap-er 89 are located beyond substantially vertical median planes of the tyres of the twa wheels ~1 and 32 that extend parallel to the direction A. The member 62 itself once again has the previously described rims 64 that co-operate scrapingly with the $acing inner sidç
surfaces of the tyres of the two wheels 31 and 32. The extremities of the scraper 89 carry end plates 90 that both extend substantially vertically parallel to the direction A, ~he end plates 90 project rearwardly from the scraper 89 with respect to the direction A
and are provided with substa~tially horizontally aligned rotatable eyes 91 which surround holes to accommodate ~hafts, bolts or the like that enable çonnections to be made to various implements and .
tools. A lug 92 projects rearwardly from the scraper 89 at a location centrally across the width of the tractor and is $ormed with a hole 93 for towing pur-poses, said apertured lug 92 constituting a towing member or ~

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hook. When, as illustrated in Figure 7, only single front ground wheels 6 are provided, those ground wheels are undriven and serve only supporting and steering functions.
~ igures 8 and 9 o~ the drawings illustrate a tractor having a frame which comprises two rela-tively pivotable portions 94 and 95. The front por-tion 94 with respect to the direction A is turnable relative to the rear portion 95 about the substantially vertical axis of a strong bipartite pivot 96. ~he front frame portion 94 comprises a hollow beam 98, the rearmost end of that beam 9~ with respect to the direction A being furnished with a fork 97 the limbs of which support the two parts of the strong pivot 96.
~he leading end of the beam 98 ~ith respect to the direction A supports an internal combustion engine 99 of the tractor. $he be~m 98 is provided, at loca-tions between the pivot 9~ and the engine 99, with substantially symmetrically arranged lateral projec-tions 100 and 101, said projections 100 and 101 bei~g similar in construction and function to the previous-ly described projections 48 and 49. Once again, a differçntial is located inside the hollow beam 98 and partially within its projections 100 and 10~, said dif- -ferential being driven from a shaft which extends from the tor~uç canverter to the di$ferential. ~he torque converter is coupled ~o the oubput of the engine 99 and is not shown in the drawin~s. Output or half shafts extend coaxially in opposite direçtiors from the pro-_ 23 -'' ' ' , ' 1~)5452~
jections 100 and 10~ and have hub portions of front ground wheels 102 and 103 releasably secured to discs at their outer ends. ~wo further front ground wheels 104 and 105 are arranged beyond the ground wheels 102 and 103 respectively, the connections between the hub portions of the wheels 102/104 and 103/105 being the same as has already been described with particular reference to ~igure 6 of the drawings. Thus, the proaections 100 and 101 extend into the internal cav-ities of the wheels 102 and 103 respectively together with the half shafts or output shafts of the differ-ential. As seen in side elevation (~igure 9), the stron~ pivot 96 is lo¢ated very close to the rearmost extremities of the row of wheels 102 to 105, with res-pect ta the direction A, the engine 99 being located wholly in front of said row of wheels relative to the same direction.
~ wo tanks 106 and 107 which are arranged to contain liquia fuel for the engine 99 are,disposed in sy,m~etrical relationship at the front of the tracbor, said tanks being secured to opposite substantiall~
vertical side walls of a housing of the engine 99.
~he fuel tanks 106 and 107 are thus also located wholly in front of the row of wheels 102 and 105 with respect to the direction A~ ~he two tanks 106 and 107 projeo~ from opposite sides of the housing of the en-~ine 99 and, as seen in plan view (~igure 8), each of them is of substantially right-angled triangular con-figuration. As seen in ~igure 8, the "opposite" sides '' ' .~

- 24 - , ,, . .:
;
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16~545Z~
of the triangles coincide with the substantially ver-tical side walls of the engine housing, the "adjacent"
sides of the triangles projecting perpendicularly from said side walls at the rear of the "opposite" sides and the two "hypotenuses" are in forwardly convergent relationship with respect to the direction A and sub-stantially intersect the "opposite" sides at the fronts of the triangles.
~ he leadin~ end of the rear frame portion 95 is engaged around the strong pivot 96 between the upper and lower limbs of the fork 97. ~he rear frame portion 95 has substantially the same width as does the beam 98 that forms part of the front frame portion 94, said width pre$erably being between substantially 20 centimetres and substantially 40 cenbimetres, ln-clusi~e. The e~ine housing that is supported by the beam 98 has, as ca~ be seen in ~i~ure 8 of the drawings, a considexably ~reater wid~h and parts that are carried by the rear frame portion 95 are also of greater width.
The frame por~ion 95~ which is of hollow formation, is provided wi~h substantially symmetrically disposed oppo- -site lateral projections 108 a~d 109 clo9e to its rear end with respe¢t to the direçtion A. The proaections 108 and 10~ form part of a differential hosuslng and are similar in construction to the projections 48/49 and 100/
101 that have been referred to aboveO The projections 108 and 109 extend into internal cavities of two rear ground wheels 110 and 111 together with the axle housingq of half shafts or output shafts of the last-mentioned differential.

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lOS~528 ~wo further rear ground wheels 112 and 11~ are mount-ed alongside the ground wheels 110 and 111 respective-ly to form a row of four rear ground wheels, the con-nections between hub portions of the wheels 110 and 112 and the wheels 111 and 113 being effected in the same manner as has already been described above with particular reference to ~igure 6 of the drawings. ~he hollow frame beam that principally affords the rear frame portion 95, together with its projections 108 and 109, is substantially the equivalent of the dif-ferential housing 4 and lts projections 48 and 49.
Similarly, the rear ground wheels 110 and 111 corres-pond to the rear ground wheels 31 and 32 of the first ~ :
embodiment. It iwll, however, be noted that,. in the embodiment of Figures 8 and 9 of the drawings, part of the rear frame portion 95 is disposed between the first row of fronb wheels 102 to 105 inclusive and the rearwardly spaced second row of rear wheels 110 to 113 inclusive.
~ he sizes of the pneumatic tyres of ~he wheels102 bo 105 and 110 and 113 a~d the distances between them may conveniently be the same as has already been described with reference to the rear ground wheels 5 of the embodiment o~ ~igures 1 to 6 of the drawings or to the embodiment of ~igure 7 thereof. ~he same is, ~.
of course, true o$ the wheels themselves. Similarly, the different tread pabterns of the tyres of the inner wheels 31 and 32 as compared with those o~ the tyres of the outer wheels 30 and 33 may advantageously be ,, .. ~ ~, . ., ;. . ~ .
. : , . ,:. . ., , . ~ ~: -.. .. . . . . , . . : , 11~545Z8 employed for the inner wheels 102, 103, 110 and 111 as compared with the outer wheels 104, 105, 112 and 113.
~igures 8 and 9 illustrate -the provision of a rear lifting device or hitch that incorporates the previous-ly described member 62, the scraper 89 and the aper-tured end plates 90. However, if preferred, the rear lifting device or hitch of the embodiment of Figures 8 and 9 of the drawings may also incorporate a rear tow-ing hook in the form of the apertured lug 92 that is illustrated in Figure 7.
As mentioned above, the output shaft of the engine 99 drives a tor~ue converter that is not illus-trated and, in turn, the torque converter is arranged to rotate an output or driving shaft 114 that extends substantially horizontally rearwardly therefrom. ~he re~rmost end ~f the driving shaft 114 is provided with a universal joint 115 whose centre is coincident with the axis that is defined by the separate coaxial upper and lower portions of the strong pivot 96. The univers-al joinb 115 is connected to the front of a further driv-ing shaft 116 that extends rearwardly therefrom into the differential housing from which the rear wheels 110 to 113 inclusive are driven. ~hus, all eight of the ground wheels 102 to 105 and 110 to 113 can be driven simultaneously.
~ driving ~eat 117 is mounted on a frame 118 thab also support~ a steerin~ wheel 119 and other con-trols (not il]us~rated? for the operation of the trac, tor. ~he ~rame 118 and the parts which it carries are ,~ .

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~35452~
turnable through substantially 180 about a~ upright pivot 119 ~ between the position illustrated in Figure 9 of the drawings in which a driver occupying the seat 117 faces forwardly with respect to the direction A and a po~tion i~ which he will face rearwardly with respect to that direction. Means (not illustrated) is provided to retain the frame 118 in either of the two positions that have ~ust been mentioned. In the position of the frame 118 that is illustrated in ~igure 9 of the draw-ings~ the driving seat 117 is located substantially exactly vertically above the common axis of rotation of the rear ground wheels 110 to 113 inclusive where- -as, when the other possible operative position of the seat 117 is employed, said seat will be located above front regions of the ~heels 110 to 113 inclusive as seen in side elevation and with respect to the direction A. ~he seat 117, the steering wheel 119 and the other controls (not shown) are enclosed in a driving cabin 120 that has a front door (not shown). Access to the front door is b~ way of a flight of steps 121 which comprises rungs 122 and 123 that are located in a symmetrical ~an-ner at opposite sides of the rear frame portion 95 -and further rungs 1~ that are located substantially ce~trally above the frame portion 95 to terminate near the foct of t~e front door of the cabin 120. ~ach of the rear driven ground wheels in each of the embodi-ments that has been desçribed has an overall diameter which should not be less than substantially 100 centi-metres and which is advantageously between substantial- ~ -.

ly 140 and 180 centimetres. A diameter of substantial-ly 150 centimetres is employed in the examples which have been specifically described.
High powered tractors that can exert a strong driving torque on their driven ground wheels are often incapable of transforming that driving torque wholly into tractive effort since, for example, heavy and/or prolonged rainfall can soften the ground to such an extent that the driven wheels skid or sink into the soil surface. So-called cage wheels have been pro- -~
vided alongside driven pneumatically tyred ground wheels that are suitable for use on public roads and that form part of the original equipment of the trac-tor in an effort to extend the area of contact between the wheels and the ground surfaçe during operation on sq~t land but, although they improve the proportion of the drivingtorque that c~n be converted into ~ractive effort, their provision substanti~lly increases the overall width of the tractor to such an extent that it cannot be driven along public roads in most countries without breaking the laws of those countries. Although it is, of course, possible temporarily to remove the cage wheels for public road transport purposes, this is tiresome and inconvenient when frequent journeys along public roads have to be made. Many known trac-tors have the disadvantage that their origina~ s-tand-ard widths are equal or very nearly equal to the leg-ally prescribed maximum road transport widths of the countXies of origin so that the addition of driven .. . . .~ ~ .

16~545Z8 cage wheels or the like with a view to increasing the area o~ contact with soft soil when the tractor is in use makes it illegal to drive th~ tractor along public roads. Without the added driven cage wheels or the like, the area of contact between the original wheels and so~t soil is insufficient so that the trac-tor cannot produce enough tractive effort to move many heavy implements and tools without skidding, wheel spin or serious sinkage into the unstable ground surface.
~ractorsin accordance with the invention may have a large area of contact between their tyres and the soil surface so that they can produce a high tractive ef-fort befqre significant wheel slip or sinkage will occur and this important advantage is realised with-out having an overall tractor width that infringes public road transport regulations. ~he overall width of that part of the tractor frame to which the driven wheels are connected is drastically reduced as compared with conventio~al tractors so that there is sufficient space for a row of driven ground wheels whpse tyres, in total, have a lar~e area of contact with soft ground and consequently exert a low pressure u~on the ground surface per unit area o$ tyre in contact therewith. ~hus~
under all but the most extreme of adverse conditions, substantially all of the engine torque that is applied to the driving of the ground wheels can be utilised as tractivç effart. ~he maximum permitted width of the tractor (for road transport purposes) is thus utilised in an optimum manner and a tractor in accordance with - ~0 -the invention can be used satisfactorily in soil con-ditions which wou~ render the employment of a conven-tional tractor either very difficult and uneconomic or substantially impossible.
~ he engine 7 of the tractor that has been des-cribed with reference to ~igures ~ to 6 of the drawings drives the sha~t 37 by way of the torque converter 3, -which may beamanual gear box, and said shaft 37 is enclosed in the housing 4 which is no greater in width (thickness) than one of the tyres of one of the driven rear wheels 5. Such width should not be more than sub-stantially 50 centimetres and it is preferred that it should be within the range of substantially 20 centi-metres to substantially 49 centimetres~ ~his small width is possible because the distance between the substantially vertical side cover plates or the like 34 of the housing 4 is determined principally by the dimensions of the bearings 35 and 36 of the shaft 37.
Although the portion of the housing 4 which actually contains the differ-ential is greater in width than is the remainder of that housing, this does not destroy the advantages of the invention because the projections 4~ and 49 that partially contain the differential are ente~ed into the hollow interiors of the inner ground wheels 31 and 32, such ground wheels being commercial.
ly available tractor ground wheels that, accordingly, do not have to be purpose-built for employment with tractorsin accordance with the invenbion~ ~he hub portions 57 and 58 have flat parts that are located ,, ~ . . .. . . .

105'~528 laterally beyond the general planes of corresponding sides of the tyres of the wheels concerned and this enables the hub portions of two different wheels to be quickly and easily fastened to one another in abutting relationship. The distance between the flat part of each such hub portion and the general plane of the neighbouring side of the tyre of the wheel concerned is the principal ~actor in determining the distance between the tyres of two immediately neighbouring wheçls of one of the rows of such wheels that have been described. However, it is not essential that the hub portions should have the shapes that have been described in regard to the portions 57/58 and 60/61.
As an alternative, tractor wheels ~ay be used which have hub portions comp~ising flab parts that are sub-stantially coincident with, or located internally be-hind, the general planes of the sides of tyres when ~itted to the corres~onding wheels. When such whèels are employed, the tyres that are fitted thereon abut a6ainst one another in side-by-side relationship with substanbially no space ab all between them except where the housing 4 is situated. Apart from that necessary sp~ce, substantially the whole of the prescribed width (for public road transport purposes) of the tractor can be occupied by pneumatic tyres and no significant amounts of mud w~ll be able to penetrate between the abutting tyres without the provision of scrapers.
It can 4e seen in Figure 6 of the drawings that it would be possible to increase the width of the dif-~.
_ ~2 ~ ~

. .

ferential by ~h~rtenin~ the axle supports 52 and 53,the width o~ said differential being effectively the distance between the outermost extremities of the lateral proiections 48 and 49 of the housing 4. Such an arrangement can be made, when required, and is ad-vantageous inasmuch as it enables larger and stronger moving parts to be employed without adding to the overall width of the rear of the tractor provided thatthe enlarged projections still fit with adequate clearance in the internal cavities of the wheels 31 and 32. ~he available space is thus used in an optimum manner. In the embodiment of Figures 1 to 6 of the drawings, the tractor has four of the rear driven ~-ground wheels 5 that give an overall width of substan-tially 2.5 metres and, in addition, has four of the smaller front wheels 6 which latter engage the ground ~
surface with a fairly high pressure because the engine 7 is disposed above and between them. ~he significant pressure with which the ~ront wheels 6 engage the ground surface may, as briefly mentioned above, advantT
ageously be utilised in converting the driving torque of the engine 7 into tractive effort by arranging hydrauliç motars for the front wheels 6 in the housings 83 and 84.
In the embodiment illustrated in Figure 7 of the drawi~gs, the transport width (without the wheels .
87 and 88) is substantially 2.0 metres and the addition of the wheels 87 and 88 increas~ that width to substan- ~ -tially 3 metres, the latter being legally allowable on ,. , . ., . . : - ~ ~

1~545Z8 public roads in many countries and being possible under special licence in others~ When the wheels 87 and 88 are m~unted in their operati~e positions as shown in ~igure 7 of the drawings, the tractor has six driven rear wheels.
~ he tractor that is illustrated in Figures 8 and 9 of the drawings has eight driven ground wheels which are arranged in a front row and a rear row with each row comprising four of the wheels, the overall width o~ the tractor being within the legally allowed limits for travel on public roads. However, if desired, each of the two rows of four ground wheels may have two further ground wheels added to its opposite ends to give a total of twelve ground wheels arranged in two rows of six wheels each in the same manner as has al- :
ready been described with reference to the rear ground wheels of the embodiment of Fi~ure 7. Onoe again, it is possible to dispose a larger than usual number of driven ground wheels within a limited width since ~he shafts 114 and 116 are inside a narrow frame that has a width of between substantially 20 and substantially 50 ¢entimetres, said frame extending from the engine 99, which is located at the $ront of the tractor, rear- -wardly between the front ground wheels 102 to 10~ to the differential for the rear ground wheels 110 to 113.
The very narrow frame, which is afforded principally by hollow beams that accom~odate driving shafts, has the advantage that, if required, more than two rows of driven ground wheels could be provided. ~hus, in any - 34 - . . -1~545Z~3 one of the three embodiments that has been described, a third row of four or six closely adjacent driven ground wheels could be provided thus further reducing the pressure per unit area of contact between each tyre and the ground surface. Even in very soft or waterlogged soil, sinkage can thus be reduced to an extent that does not interfere significantly with operatlon and it is almost always possible to trans-form all of the engine output that is available for that purpose into tractive effort.
Generally speaking, the grip of pneumatic tyres upon the ground is enhanced if those tyres have tread patterns which exhibit large teçth and tractors that are employed in ploughing operations are fre~uent- ~
ly furnished with such tyres. However, pneumatic tyres ~ -that have tread patterns with teeth o$ large radial ex-tent are expensive. ~he arrangement shown in Figure 5 of the drawings can reduce this expense because the pneumatic tyres of the outermost wheels 30 and 33 of the row of four wheels 30 to ~3 inclusive are tyres whqse treads have teeth 85 of comparatively small rad-ial extent, said teeth being, however, relatively close together around the circumference of the tyre. ~he teeth 86 of the treads of the tyres of the inner wheels 31 and 32 are teeth of relatively large radial extent so that said tyres are ~hus of the expensive kind dis-cussed above, the teeth being spaced apart, however, around the circumference of each tyre by ~reater distances than are the teeth 85 o$ the tyres of the wheels 30 - 3~ --1054SZfl and 33. ~igure 5 of the drawings illustrates the trac-tor in use in a ploughing operation with one of the outer wheels 30 travellin~ in an elready ploughed fur-row whereas the immediately neighbouring wheel 31, that is of the same overall diameter, travels on unploughed soil immediately to one side of the furrow. ~he large teeth ~6 of the tyre of the wheel 31 penetrate quite deeply into the soil and can transform all or most of the applied torque into tractive effort. ~he smaller teeth 85 of bhe tread pattern o~ the tyre on the wheel 30 do not sink into the furrow to any great extent and are quite adequate for the purpose in view thus making it unnecessar~ to provide the wheel 30 (or the wheel 33) with a more expensive tyre having the teeth 86 of larger radial extent. Since the wheel 30 travels m the already formed furrow~ the plough does not need to be markedlg offset in position relative to the path of travel of the tractor and this enables the tractor driver to steer a straight course without exerting a strong corrective effort to one side on the steering wheel 28 because the plough is nearer to the imaginary substantially vertical plane of substantial symmetry of the tractor that extends in the direction A than is con- -vèntional. If the land to be ploughed is very soft, with the result that the tractor tends to ~ilt to one side 'Qeyond the inclination illustrated in ~igure 5, the peripheral surface of the tyre of the wheel 30 from which the teeth 85 project will come into substan-tially direct co~tact with the ground surface which latter , . . . , . ... , .. .. ,,, - ...... . . . . . . ............. . ..... .

: . : . - . . ., : :,: . .

will then give a greater degree o~ support. ~iltin~
to a dangerous extent is thus prevented. Since the tyre of the wheel 30 has a large number of the teeth 85, the tyre is able to transform quite a high torque into tractive effort as soon as the teeth 85 in a lower arc of the tyre of significant angular extent have pene-trated into the soil.
~ he scrapers 67 between the tyres of the wheels 30/31 and tho~ of the wheels 32/33 and also the scrapers that are provided between the tyres of similarly disposed wheels in the other embodiments act to scrape off mud and lumps of soil from the immediately neighbouring sides of the ~yres of the wheels concerned. It can be seen from Figure 2 of the drawings that each scraper 67 covers the whole radial extent of the two tyres with which it co-operates so that the sides of the tyres in question are kept free of large accumulations of mud throughout operation of the tractor. Owing to the arcuately curved formation of the scrapers 67 that initially ~as seen in side elevation - Figure 2) extend substantially vertic-ally downwards and then forwardly towards the common axis of rotation of the rear ground wheels, there will be a tendençy for mud and the like scraped from the tyres to travel upwardly along the scrapers 67 until it moves outwardly beyond the treads of the tyres of the wheels concerned. Much of the mud will drop away to the ground surface when it reaches this location, or previously, and any that does not do so will be dis-placed rearwardly along the bottom of a corresponding 1~54528 curved guide 125, said guides 125 being substantially horizontally disposed but, as can be seen in Figure 2 of the drawings, initially projecting rearwardly and upwardly to a small extent from the tops of the corres-ponding scrapers 67 to terminate in downwardly bent-over portions. ~he guides ~25 are rigidly secured to the support lugs 69. ~he spring-loaded mounting of the scrapers 67 enables them to deflect about the corres-ponding pivot pins 68 to avoid damage in the event of, for example, a stone o~ the like becoming jammed bet-the ween/tyres of the corresponding wheels 30/~1 or 32/33.
~he rims 64 of the towing and scraping member 62 thab is rigidly secured to the bottom of the hous- :
ing 4 lie very close to the inner side surfaces of .
the tyres of the wheels 31 and 32 and mud and the -like scraped from those side surfaces by the rims 64 will sooner or later drop back onto the ground surface between the wheels 31 and 32. There is a tendency for mud and the like scraped off by the rims 64 to mo~e away from the tyres concerned towards the centre of the member 62 so that, generally speaking, when that mud falls back to the ground surface, it will be clear of contact with the tyres of both of the wheels 31 and 32. ~he rims 64 stiffen the plate-shaped towing and scraping member 62 and tend to prevent bending of the latter when the member is used as a towing hook by employing the hole 63 that is formed therein. In particular, the rims 64 tend to prevent upward deflec-tion of the member 62. ~he scrapers 65 that ca~ be 1~545Z~I

seen best in ~igures 4 and 5 of the drawings are ar-ranged to shed adhering mud and the like from at least the inner teeth 86 of the tyres of the two wheels 31 and 32 because the plates 66 at the ends - :
of the scrapers 65 are located in, or just beyond, the median planes of the tyres of the wheels 31 and 32 that extend parallel to the direction A.
The end plates 66 are employed for the connection of implements or tools during the use of the tractor and, if desired, the scrapers 65 can be extended out-wardly beyond them to embrace substantially the whole of the width (thickness) of the tyre of each of the two wheels 31 and 32. ~he scrapers 65 co-operate with the treads of the tyres of the wheels 31 and 32 in the manner of butter curlers and the removed mud curls away downwardly and rearwardly behind the scrapers 65 to fall back to the grou~d behind the tyres.
In the embodiments of ~igures 7 to 9 of the drawings, the member 62 is not rigidly secured to the tractor~frame 1 but forms part of the rear lifting device or hitch of the tractor, the member ~2 being provided at the back with the scraper 89 which scraper extends effectively throughout the width of the treads of the tyrçs of the wheels 31 and 32 or 110 and 111. ~he scraper 89 may be extend~ -ed laterally, if desired, to co-operate also with the treads of the tyres of at least the wheels 30 and 33 or 112 and 113. ~he scraper 89 also serves as a - \

1~54SZfl support for the end plates 90 to which an implement or tool can be connected employing the eyes 91. Scra-pers that are substantially identical to the previous-ly described scrapers 67 may be arranged between the closely neighbouring tyres of the pairs of ground wheels in the embodiments of ~igures 7 to 9 of the drawings and, in the embodiment of ~igures 8 and 9, --the fork 97 that lies between the tyres of the wheels 102 and 103 may also carry a laterally disposed scra-per (not shown) for keeping the treads of the tyres 102 to 104 inclusive clean. As previously mentioned, the rear scraper 89 may be increased in width so ~hat it will co-operate also with the treads of the tyres of the wheels 112 and 113~
In the embodiment of Figures 1 to 6 of the drawings, the engine 7 is located above and between the $ront ground wheels 6 so that the pressure of those wheels on the ground is quite high and it can be useful, as described, to arranged them so as to be drivable. However, in order that the pressure of the rear wheels 5 upon the ground should not be too low, ot~er parts of the tractor are arranged near to the common axis of rotation o$ the rear ground wheels.
Thus, the driving cabin 18 and the driving seat 27 are arranged substantially directly above the axis a~' rotation of the rear wheels 5. In the embodiment of ;
Figures 8 and 9 of the drawlngs, the engine 99 is -located in front of the ground wheels 102 to 105 with respect to the direction A and thus tends to reduce -:

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1~5~5Z~

the pressure of the rear wheels 110 to 113 upon the ground surface. In order to compensate for this, the driving cabin 120, the driving wheel 117, the controls of the tractor and the rear lifting device or hitch thereof are all located above, or close to, the com-mon axis of rotation of the rear ground wheels.
~ he driving cabin 18 of the embodiments of ~igures 1 to 7 of the drawings contains the driving seat 27 and also the cabin floor portion 19 which is at a lower level. The distance between the cabin floor portion 19 and the roof 23 of the cabin is such that a person whose height is not more than substan-tially 1.75 metres aan stand upright in the cabin and preferably at a location alongside one of the doors 20 so as not to impede bhe forward view in substantial-ly the direction A of an operator occupying the seat 27.
~ he fro~ a~d rear portions 94 and 95 of the frame of the tractor that has been described with reference to Figures 8 and 9 of the drawings are rela-tively pivotable about the substantially vertical ~xis that i5 de~ined by the strong pivot 96 and relative angular displacement of the two frame portions 94 and 95 about said axis enables the tractor to be qteered from the wheel 119. Vehicle steerability in this gen eral manner is known ~er se and , accordingly, the parts that enable it ~o be effected are not illustrated in ~igures 8 and 9 of the drawings and do not need to be described for the purposes of the present invention~
~he overall diameter of each of the wheels 102 to 105 .. . , . - . , , 1~3545Z8 and 110 to 113 of the tractor of Figures 8 and 9 of the drawings is substantially 150 centimetres and the trac-tor, when equipped with eight ground wheels as illustra-ted, has an overall width which is not greater than 3.0 metres and which is preferably substan~ially 2.5 metres. The tractor can thus travel along public roads without restriction.

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Claims (11)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A tractor comprising an engine, two groups of ground wheels, a frame which comprises at least two portions, said portions being pivotable relative to one another about a substantially vertical axis, wherein a first portion supports the engine and a torque converter coupled to the output of the engine and the second portion supports a console comprising a driving seat, a steering wheel, steering and operating controls, the first frame portion being supported by a first group of ground wheels, the second frame portion being supported by the second group of ground wheels, said console being turnable through substantially 180° about a substantially vertical axis relative to said second portion and means provided to retain said console in a position in which a driver occupying said seat faces generally forwardly and alternatively in another position in which said driver faces generally rearwardly of the tractor, coupling means being provided near at least one end of said frame for coupling at least one attachment to the tractor.

2. A tractor according to claim 1, wherein said engine is located, as seen in plan view, at least partly in front of said first group of ground wheels.

3. A tractor according to claim 2, wherein said engine is located, as seen in side view, at least partly in front of said first group of ground wheels.

4. A tractor according to claim 1, wherein said coupling means are connected to said second frame portion.

5. A tractor according to any one of claims 1, 2 or 4, wherein said coupling means comprises towing means.

6. A tractor according to any one of claims 1, 2 or 4, wherein said coupling means comprises a lifting device.

7. A tractor according to claims 1, 2 or 4, wherein said driving seat is located near one end of the frame.

8. A tractor according to any one of claims 1, 2 or 4, wherein said coupling means are located near said driving seat.

9. A tractor according to any one of claims 1, 2 or 4, wherein the driving seat is located, as seen in side view, above the front regions of the rear ground wheels.

10. A tractor according to any one of claims 1, 2 or 4, wherein said console is enclosed in a driving cabin.

11. A tractor according to any one of claims 1, 2 or 4, wherein all ground wheels are driven.