CA1036505A - Four-wheel drive articulated tractor - Google Patents

Abstract

FOUR-WHEEL DRIVE ARTICULATED TRACTOR

ABSTRACT OF THE DISCLOSURE
A four-wheel drive tractor with front-wheel steering on the front axle and rear-wheel articulated steering to provide maximum traction, stability and maneuverability while reducing working angle of drive universal joints.
The front axle pivots on a pivot longitudinal with the vehicle body and the steering wheels pivot relative to the axle to steer the front end of the vehicle. The articulated vehicle bearings are positioned near the rear axle to provide a long front body supporting portion for the operator station of the vehicle and to improve stability of the vehicle when a vehicle is articulated.

Description

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This inYention relates to a ~our-wheel driYe tractox and more'paxticularly to an articulated vehicle' ;~
having articulated steering on the rear ~heels and haYing ' front-wheel steering for steering the front wheels relative . .
to a pivoting ~ront axle.
The con~entional vehicle, such as an automobile, employs a rear-wheel drive and a front-wheel steer with a single main chassis. This type of operation -has been used ; ~' quite'extensively in'the tractors as well. With an increase ~r,~, ' in size of engines ln the tractor-type vehicles, and the advent of the ~our-wheel drive wherein the front and rear wheels are essentially the same size, the articulated vehicle '~ ' has been looked on more favorably. Various types o~ ~
art~culating jolnts have been used for pivotal relative ';' moyement on a horizontal and a vertical axis. Although the - "
conventional articulated vehicle is pivoted on a vertical '' axis, some means must be provided for oscillation of the one ~ ';
axle relative to the other due to the unevenness in the : ,..
terrain. The type of pivoting mechanism on the front'axle 20 and the pivot for the articulation of the vehicle is critical ' ~ since this does affect the stability of the vehicle. An ;, articulation of the vehicles having the articulating joint of the vehicle centrally located between the front and rear ' ~heels will cause instability particularly on uphill turns because the center of gravity is shifted outside the centerline of the vehicle. ~ccordingly, this inventlon is intended to overcome this type of instability and to provide greater . .
maneuverability as ~ell as traction necessax~ for the vehicle.

~ccordingl~, this invention provides ~or a four-wheel '';

3a driYe ~ehicle ~ith a~ticulation ~etween the ~ront ~nd rear frames of the vehicle 'cha`ssis. T~e articulation point is ' ,, , 1 ~ '~

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approximately in the ratiio of 2 to 1, or 2-1/2 to 1 between '~ ' the front and re~r ~r~mes o~ the ~ehicle chassis. The rear whee'Is are ~teered by articulation ~f the vehicle. The ront ~heels are mounted on a pivotal axle pivotally mounted under the front frame of the chassis. The front wheels are steerable on axes deflned by the pivotal connections between the wheel support and the front axle. ~ccordlngly, the vehi`cle `,,,', can be steered as a con~entional single-frame chassis or as the combined'front ~heel steering and articulated steering o~ ; , ' the rear wheels. This in turn will provide conventional steering such as the single-framed front wheel steering `, , ' type mechanism or articulated steering or a combination of ,'~" ' ,, either of these two types of steering to reduce the drive line "' ,, angularity and reduce the angle of operation of the universal '~
joints. This provides greater stability because of the ,~ , ,' steerability ~of the front wheels relative to the front axle and greater maneuverability o~ the vehicle., ~' , It is an object of this invention to provide a '~
four-wheel drive tractor with steerable front wheels on a ',,''' front axle and articulated steering on the rear wheels of the tractor to provide front-wheel steering and crab steering ', for the vehicle. ~,~
It is another object of this invention to provide a pivotal front axle with steerable wheels on the axle and '~
an articulated chassis with the front frame being substantially ;, longer than the rear ~rame on the vehicle.
It is a further object o~ this invention to provide a four-wheel dri~e tractor ~ith steerable front wheels and an axticu~ated chassis with'articulated rear-w~eel Steering ~" ' 30 to ~educe the driYe 'line'an~ularit~ while tuXnin~. ' ',,: .. . ..
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~036505 ~t is a further object o~ this in~ention to pro~ide a four-wheel dri~e vehIcle ~it~ steerable front ~heels on a -;;
pivotal front axle and articulated vehicle rear-wheel steering to pro~ide a three-point hitching arrangement to avoid implement engagement with the` rear wheels when turning.
~ t ~s a further ob~ect of this invention to provide an articulated vehicle having axticulated rear-dri~e wheel steering and a pivotal front axle with steerable front wheels i;`
steerable about essentially vertlcal pivotal axes to increase the maneuverability o~ the vehicle.
It i8 a ~urther object of this invention to provide a four-wheel drive tractor having an articulated chassis with a pivotal front axle ha~ing steerable wheels and articulated steering on the rear wheels with a long ~ront bogey and a short rear bogey to increase stability and maneuverability of the ~ehicle during articulation or steering of the vehicle.
The objects of this invention are accomplished by providing a four-wheel drive vehicle. The vehicle chassis includes a front frame and a rear frame with articulation 20 rearwardly of the center of the vehicle chassis. The rear ;;
axle is supported on the rear wheels and the steering of the rear wheels is controlled by hydraulic actuators in connection with the articulated joint of the vehicle chassis.
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The front axle of the vehicle is pivotally mounted on the front frame and allows for the pivoting of the front axle in response to the unevenness o the terrain. The front wheels are steerdble on the axle and are steered hydraulically in response to the hydraulic controls by the operator. The drlve ~or the front and rear wheels is a mechanical drive throu~h uni~ersal joints runnin~ fore and a~t fro~ ~
transmission drop box centrally located on the vehicle ~- _ 3 _ ! ' ' , ~(J365Q5 :
chassis and supported on the front frame. The articulated joint on the vehicle chassis pivots on a top and lower bearing -to maintain the upright position of the front frame while the rear wheels maintain the stability and position of the front -and rear frames. The articulation joint is positioned inter-mediate universal joints on the rear drive line. Since the front axle is pivotal relative to the front Erame, this does ; ;
not maintain the upright position of the front frame, but merely allows for the front wheels to maintain traction while the vehicle is in operation. With the front-wheel steering and ~ `
the articulated steering of the rear wheels, the steerable angle of the articulated joint can be substantially reduced and accordingly the drive line angularity is also reduced while the stability of the tractor and maneuverability o~ the tractor is maintained.
In accordance with the invention, a four-wheel drive tractor comprising, a chassis including a front frame and a rear frame, an engine supported on the front frame of said chassis, means defining an operator station on said front frame, a front axle, a front end carriage integral with said ~
axle pivotally supporting the front frame of sai~ chassis for ~ -:
pivotal movement on a longitudinal axis, front steerable drive wheels rotatably supporting said front axle and pivotal movement relative to said front axle about vertical axes for front end steering, front wheel steering mechanism pivoting said front wheels relative to said front axle or steering the front wheels, a rear axle rigidly supporting said rear frame and maintaining stability of said rear frame, a pair of rear drive wheels rotatably supporting said rear axle, articulating `
joints defining a vertical pivotal axis pivotally connecting ; ~;.
the rear end of said front frame with the front end of said ;-~

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rear frame of said chassis at a point approximately three-fourths the distance from the front axle to the rear axle, means positioning said articula~ing joints in vertically spaced ;
relation to maintain stability from the rear frame to the front frame, an articulating steering mechanism for articulation of said chassis, a steering wheel and steering control means for selectively steering said ~ront wheels through said front wheel steering mechanism, a manually operated articulating steering member and articulating steering control means operating independently of front wheel steering for selectively and independently steering said tractor through said articulating steering mechanism to provide left turn, right turn, and crab steering in response to selective operation and dir~ction o~
steering of said steering wheel and said manually operated articulating steering member, a mechanical drive train connected to said engine for driving said wheels including a transmission with a propeller shaft for driving said front : :.
wheels and a propeller shaft for driving said rear wheels, a plurality of universal joints in each of said propeller shafts, said steerable front wheels and said articulated chassis thereby requiring a minimum angularity of universal joints on the propeller shaft for said rear wheels when driving said tractor and increasing stability and maneuverability of said tractor.
Referring to the drawings, the preferred embodiment of this invention is illustrated:
Fig. l shows a partially sectioned side view of the vehicle;
Fig. 2 illustrates a plan view of the vehicle;
Fig. 3 ilIustrates a schematic diagram of the hydraulic system for operating the vehicle;
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Fig. 4 shows crab steering of the vehicle and the , .
limited angularity of the drive line on the vehicle;
Fig. 5 illustrates front-wheel steering for the vehicle; ~
Fig. 6 illustrates front~wheel steering in the right- ~ `
hand direction and rear-wheel articulated steering in the left-hand direction on the vehicle;
Fig. 7 is a plan view of the front axle and front end .. ...
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carriage; and ~;

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Fig. 8 is a ~ront elevation ~iew of Fig. 7. .
Referring to the drawlngs, ~ig. 1 illustrates a partially sectioned side view of the tractor 1. The tractor . .
includes a platform 2 supporti.ng the seat 3 at the operator station 4. The steering wheel 5 is mounted on the control console 6. The engine hood 7 is mounted between the control console 6 and the grill 8 mounted in front of the radiator.
The r~dlator and the grill 8 and engine 9 are mounted on the ~
frame 10 which is a part of the vehicle chassis. .
The engine 9 drives through the transmission 11 which dri~es inko the drop box 12. The drop box 12 drives ., forwardly to the shaft 13 and the uniYersal joint 14 and ;
the intermediate sha~t 15 and universal joint 16. Universal joint 16 drives into the shaft 17 and a dif~erenkial in the ~:.
front-wheel drive 18. A ront-wheel drive shaft 19 drives . .
one of the front wheels. Front wheels 20 and 70, of which ~ :
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one is shown in Fig. 1, support the front end of the tractor. .
The front end carriage 21 is connected to the front axle 22 and is pivotally supported on the pins 23 and 24, ..
which in turn are mounted in the brackets 25 and 26 o the front frame end. Acoordingly, the front carriage 21 is `'h~
pivotal on a 1ongitudinal axis of the tractor 1.
The drop.box 12 also dri~es rearwaxdl~ ~hrough the ..
shaft 27, the universal joint 28 and the intexmedlate shaft 29 and the universal joint 30. The uniYersal joint.3~ driYes shaft 31 and through a.di~ferential in the reax a~le ass~bl~ ~.
32. The reax dri~e asse~bly.32.drives through the rear axle 33 to one of the rear wheels. The rear wheels 88, of ~`
whiah one ifi $hown in P~g. 1, support the Xear fra~e 34.
The re~r ~r~e 34 ~nclude$ the ~x~ckets 35 and 36 Which are pivotall~ connected t~ the clev~ses 37 and 38 on the ~Xont _ 5 _ ;~

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frame lO. The upper bear~ng 39 for~ed by bxackets 35 ";and cleYis 3 7 ~S p~yotally cQnnected by the pin 4Q while the lower bearing asse~ly 41 ~ormed by bracket 36 and clevis 38 !`
is pivotally connected by the pin 42. '''"' ,' .... ..
The rear drive housing 43 plvotall~ supp~rts the ~ ;' rock shaft 44 and the rock arms 45 are pivotally connected to the lift links 46. A pair of lift l~nks 46 raise and ' ;
lower the lower draft arms 47 in response to movement of the , ' rock shaft 44. The-iower draft arms are connected'through ,, ' arms 48 on the rear drive assembly to a suitable draft ; ,.
moVement sensing mechanism. ` ~', The implement 49 i9 connected to the uppex link 50 ;' by a pi~ot pin 51. The implement includes a mast 52 which ~;;
extends downw,axdly and ~s connected to the lower draft arms 47 by means of a pivot pin 53. The drawbar 54 is supported ''' by a drawbar bale 55 and the bracket 56 connected to the rear ,; ' drive housing 43. ~ ' - ;.
In Fig. 2, the articulating bearing 39 is shown ',' ~, ' which is immediately above the bearing 41. The hydraulic i , actuators 60 and 61 are supported on the brackets 167 and 168 on ,~
the front frame 10 and pivotally connected to the brackets 58 ','`
and 59 on the rear frame 34. Selective actua~ion of the hydraulic actuators 60 and 61 provides articulated steering of the rear wheels 88. This steering mechanism is provided ''~;
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through the hydraulic system shown in Fig. 3.
Figs. 7 and 8 show the steering mechanism for the front ~heels. The carriage 21 is mounted on the housing of ' ;
the front whee'l drive 18. The brackets 62 and 63 connect ';
the c~rriage to the front a~le 22. The hydraulic actuator 64 , 30 ~s mounted on the bracket 65 on the carX~e 21 ~nd selec~
ti~el'y operates the'steering arm 66. The steering arm 6 ~
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pi~ots the right front wheel 20 on its plvotal axis. The tie rod 67 connects the ar~ 68 with'the'a~ 6~'~o steer a left front wheel 7a on lts p~Yotal axi5. ~ccordingly, the front wheeIs are'stee'red b~ pivotal movement of the wheels 20 and ,' 70 on their respective pi~otal axis.
Referring to Fig. 3, the pump 72 recelves hydraulic ~
~luid from the reservoir 73 and pressurizes fluid in the "~ ' hydraulic line 74. ~ relief Yalve 75 is connected on the `" ,', discharge pump 72 to relieve excess fluid pressure in the ' conduit 74. The hydraulic actuator 64 is connected through the ~' control valve 76. The control valve 76 is controlled by the '' , steering wheel 5. The control valve 76 includes a neutral ~' section 77 as well as a let turn and a right turn section 78 and 79. Also connected to the high pressure conduit 74 is con- , duit 81 which lead's to control ~alves 76 and 83, respectively.
The return line 80 is connected to conduit 82 which leads from ,`,, the control val~es 76 and 83 to the reservoir. The control ~alve 83 controls the articulated steering through the lever 84 which operates the control valve 83 between the neutral '' position 85 and the right and left hand turn sections 86 and 87. `~ ' , ;~ The articulated steering selectLvely operates through the r~
hydxaulic actuator 60 and 61 to proYide articulated steering ' of thé rear frame 34 relative to the front frame 10.
' Fig. 4 illustrates the crab steering of the vehicle ~,~
in which the front wheels 20 and 70 are steering in the right-hand direction while the articulated steering of the rear wheels 88 are steering in the right-hand direction.
The'dri~e line 29 to the ~ear ~heels re~uires a sllght amount ~f angular~ty to provide for crab steexlng.
Fig. 5 illustrate~ con~entional steeXing ~n whlch the'dri~e line'29 extends in essentiall~ a strat,ght line ~ , _ 7 _ ..

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between the rear ~rame 34 and the front frame lQ of the chassis.
When the vehicle ~s operated in this manner, it operates as a convent~onal single-frame chassis in whtch front-wheel steering is used to control the mo~ement of the vehicle.
Fig. 6 illustrates steering of the vehicle in which the front wheels 20 and 70 are being steered by the '. ". .:
front steering mechanism in the right-hand direction and the` `
rear articulated steering provides for steering of the rear wheels în the left-hand direction. In this manner, the ~ `
vehicle steers ~ith a minimu~ amount of scuffing of the tires as the rear end of the vehicle is moved in the left-hand direction and the front end of the vehicle is moved in the ~ ;
.,~, right-hand direction.
The operation o~ the de~ice wlIl be described in `~

the following paragraphs:

The vehicle shown in Fig. 1 is an articulated ~ `;`
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vehicle. The articulation of the vehicle is on the bearings `

39 and 41. The vehicle is steerable by articulation of the `
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vehicle through the hydraulic actuators 60 and 61 in the ,--~

~ 20 hydraulic circuits~shown in Fig. 3. The vehicle is also ;~ ~ steerable by steer`ing the front wheels 20 and 70 which pivot on their axes in response to operation of the hydraulic .:
actuator 64. The front end carriage 21 pivots on the pins 23 and 24 to keep the wheels of the vehicle in traction although the terrain is unneven. Traction of the vehicle is provided on all four wheels and the drive to the four wheels is provided through the txans~isiaion ll and the drop box 12 ;
and drive means including uni~ersal joints.
The articulation of the vehicle is between thè front r~e 1~ and rear ~rame 34 With a r~tio o~ appxo~i~atel~ 2-1/2 , to 1 between the ~ront frame`and xeax fxame of the chassis.
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Since the ~ront wheels are turned by selecti~e operation of the steering wheeI 5, it turns the vehicLe left or right by select~ve operation of the section 78 or ~' .
79 ~f the control Y~l~e 76. When the articulation of the "
vehicle is not used,,the Yehicle is used as a conventional ; 'r . .
front steerable vehicle. The articulated steering on the rear wheels is accomplished through selecti~e actuation o the hydraulic actuators 60 and 61. The control le~er 84 selecti~ely operates the control valYe 83 for selective 10 operation of the section 86 or 87 to operate the hydraulic `~
actuators 60 and 61. The rear wheels 88 and the rear frame 34 can be shifted at an angle to the right or let relatiYe to the ront rame 10 to provide steerlng of the vehicle in response to mo~ement of the ,actuators 60 and 61.
The wheels 88 can be steered either right or left regardless of the steering direction of the front wheels 20 and 70.
AccordingLy, to shift the rear frame to steer the rear wheels of the vehicle in the same direction as the front wheels are being steered will provide crab steering. To shift the 20 rear wheels to steer in the opposite direction from the front ~ -, wheels will cause the vehicle to turn in the direction of -, the steering of the front wheels and shift the rear end of the vehicle in the opposite direction and steer the vehicle ,, more rapidly than if only the front wheels were used in '~
steering. It is noted that because the front wheels can be steered relative to the front axles, a lesser amount of angularity is re~uired of the driYe line between the drop ,, bo~ 12 and the reax dr~ve assembly 32. Bec~use less angulaxity is re~uixed o~ the driYe llne components, the dri~e'line ,should be m~re reliable ~nd assure longer life of the 'drive 'line in the vehicle. The articulating ~ _ 9 _ .' , ... . . ~ . , - ~ ".... .

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bearings of the vehicle fox articulation ~etween the front ,~
sect~on 10 and the rear ~ection 34 are'located between the '~
rea~ wheeIs 88 of the 'rear section 34. The length o~ the ` ~' ~ront frame between the front axle and the articulating joint as compared to the length of the rear frame 34 is approximately 2 to 1 ox 2-1/2 to 1. Thls pro~ides for more stable operation of the vehi'cle. The level of the vehicle is controlled by the two rear wheels 88 and the central pivot of the front end " ~ ,. ..
carriage 21 under the ~ront frame 10. ~'ith the positioning '~
10 of the pivoting axis fox articulation of the ~ehicle rear- ", wardly of the center of the chassis a more stable vehicle ~; ' is provided. The pivotal movement of the carriage 21 and a front axle with the front frame provides for the necessary ', oscillatlng movement in response to the unevenness of the terrain.

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Claims (10)

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. A four-wheel drive tractor comprising, a chassis including a front frame and a rear frame, an engine supported on the front frame of said chassis, means defining an operator station on said front frame, a front axle, a front end carriage integral with said axle pivotally supporting the front frame of said chassis for pivotal movement on a longitudinal axis, front steerable drive wheels rotatably supporting said front axle and pivotal relative to said front axle about vertical axes for front end steering, front wheel steering mechanism pivoting said front wheels relative to said front axle for steering the front wheels, a rear axle rigidly supporting said rear frame and maintaining stability of said rear frame, a pair of rear drive wheels rotatably supporting said rear axle, articulating joints defining a vertical pivotal axis pivotally connecting the rear end of said front frame with the front end of said rear frame of said chassis at a point approximately three-fourths the distance from the front axle to the rear axle, means positioning said articulating joints in vertically spaced relation to maintain stability from the rear frame to the front frame, an articulating steering mechanism for articulation of said chassis, a steering wheel and steering control means for selectively steering said front wheels through said front wheel steering mechanism, a manually operated articulating steering member and articulating steering control means operating independently of front wheel steering for selectively and independently steering said tractor through said articulating steering mechanism to provide left turn, right turn, and crab steering in response to selective operation and direction of steering of said steering wheel and said manually operated articulating steering member, a mechanical drive train connected to said engine for driving said wheels including a transmission with a propeller shaft for driving said front wheels and a propeller shaft for driving said rear wheels, a-plurality of universal joints in each of said propeller shafts, said steerable front wheels and said articulated chassis thereby requiring a minimum angularity of universal joints on the propeller shaft for said rear wheels when driving said tractor and increasing stability and maneuverability of said tractor.

2. A tractor as set forth in claim 1 including means for positioning said articulated joint pivotally connecting said front frame with said rear frame of said chassis at a point defining a front frame length between the front axle and the articulated joint and a rear frame length between the articulated joint and the rear axle with a ratio of at least 3 to 1.

3. A tractor as set forth in claim 1 wherein said articulating joint pivotally connecting said front frame with said rear frame of said chassis includes means positioning said joint between the forward portion of said rear wheels.

4. A tractor as set forth in claim 1 including said articulating joints pivotally connecting said front frame with said rear frame of said chassis and means limiting the total angle of articulation.

5. A tractor as set forth in claim 1 including a three-point hitch mounted on said tractor adapted for connection to an implement.

6. A tractor as set forth in claim 1 wherein said means for operating said steering of said front wheels and said rear wheels includes hydraulic steering means.

7. A tractor as set forth in claim 1 including means for supporting an implement on the rear frame of said chassis wherein said rear frame on said rear wheels trails said front frame and provides an implement support for steering said implement.

8. A tractor as set forth in claim 1 wherein said means for steering said front wheels and said rear wheels includes hydraulic steering means for selectively steering said front wheels in either of two directions and hydraulic means for selectively steering said rear wheels in either of the two directions regardless of the direction of steering of said front wheels.

9. A tractor as set forth in claim 1 including fore and aft universal joints in said drive train driving said rear wheels, means positioning said articulating joint pivotally connecting said front frame with said rear frame of said chassis at a midpoint between said fore and aft universal joints to reduce drive line angularity.

10. A tractor as set forth in claim 1 wherein said means for steering said front wheels and said rear wheels includes hydraulic means for steering of said front wheels relative to said front axle, hydraulic steering means for articulating said vehicle chassis.