CA1056873A - Off-road vehicle - Google Patents

Abstract

OFF-ROAD VEHICLE
ABSTRACT OF THE DISCLOSURE
A high-mobility wheeled vehicle for transporting long loads over roadless terrain. The vehicle has front and rear quad wheel assemblies pivotally connected to a centrally disposed elongated bed frame so as to permit lateral rotation of these assemblies about the longitudinal axis of the frame. A roll control means interconnects the quad wheel assemblies and the bed frame to proportionately control the relative angular movement. The wheels of each quad wheel assembly are paired together by walking beam members, thus providing a suspension system having balanced load distribution between the wheels over a wide range of terrain rough-ness conditions. A differential drive system provides a balanced distribution of power to each wheel on both assemblies under all wheel drive conditions. Preferably, each of these wheels is steer-able and the steering control means provides for oblique travel in conjunction with conventional steering.

Description

S~MARY OF THE INVENTION
Generally spealcingg this invention relates to sel.-propelled vehicles used primarily to transport long loads acrossroadless terrain. More specifically, it relates to rubber-tired vehicles that have wheel suspension and drive mechanisms which provide balanced weight and power distribution between its wheels.
In summary, the vehicle comprises an elongated bed frame that forms the backbone of the vehicle. This frame is balanced on the central portions of modular front and rear wheel assemblies, preferably each having four quadrilaterally spaced wheels. The quad wheel suspension system is designed to provide a freedom of movement about roll and pitch axes that are .`~

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vertically spaced one above the other~ The quad wheel assemblies are pivotally mounted on the beam so as to be movable about roll axis which parallels the longitudinal axis of the vehicleO On the lower or pitch axis of each quad wheel assembly two walking beam members, each carrying a pair of side wheels, are rockabably mounted in a balanced relationship. Thus the walking beams may rock about the pitch axis of the quad wheel assembly while the quad wheel assembly itself may pivot about the roll axis. A mechanical interconnection that extends from one quad wheel assembly to the -frame and from there to the other quad wheel assembly controls the relative rotational position of these members.
The drive train utilizes a series of differentials to divide the power between the two quad wheel assemblies and deliver it equally to each driven wheel. Locking means on these differen-tials provide an antislip feature for use when one of the driven wheels breaks traction with the ground.
` Preferably all of the wheels are steerable and the steer-ing system is designed to provide oblique or sidewise travel as . .j well as conventional turning.
A vehicle equipped with this combination of features ~ has numerous advantages over prior art off road vehicles~ including `~ center frame articulated vehicles and track-laying type vehicles.
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The advantages become more pronounced when the vehicle is used -~
~ ior transporting long objects~ such as trees hauing a length of ~
; 40 feet or~more~ over soft and broken or uneven ground. When~ -, ~ ~ . , .- . .
obstacles such as rocks, fallen trees or ditches arP encountered ~; by the vebicle of this invention, its wheel suspension maintains ~, . .
~ substantially equal loading on each wheel, An important àdvantage .
of this invention is the efficiency provided by its mechanical , ., ,' '' ,' '.,.

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~ 56873drive train. The integrated design and placement of the various drive line and suspension components provide ruggedness and durability commensurate with continuous and se~ere operating conditions. Extensive use of modular components serves to reduce production and maintenance costs. Another important advantage is that all of these capabilitiès are incorporated in a vehicle that has a relatively low height and center of gravity.
According to one broad aspect, the invention re~ates to a self-propelled vehicle adapted for use over roadless terrain) -said ~ehicle comprising, in combination, an elongated bed frame, a fron~ wheel assembly pivota~ly mounted on said frame to ¦~
permit pivotal movement of said wheel assembly about a '.:
longitudinally extending roll axis, a similarly mounted rear wheel assemblyr and a roll control means interconnecting said wheel assemblies with each other and with said frame such that the frame is proportionately rotated about its roll axis by the rotation of said wheel assemblies relative to each other, said elongated bed frame being operatively connected to said ~
~- 20 front and rear wheel assemblies by springless mounting means, ~ -said rol~ control means compri~ing torque tube members affixed ~ ~;
.. ~ , .
to re~pective wheel assemblies, said torque tuhe members extending towards each other longitudinally of said bed frame and gear means interconnecting adjacent ends of said torque ;1 tube membçrs, whereby relative rotation of one tube member causes an equal and opposite rotation of the o~her tube member, 1 said gear means being selectively fixed rotationally with ;~ re~pect to said bed frame by adjustable ~eans, whereby saia bed frame may be adjusted and le~eled to the left or to the right side independPntly of the ~orces resulting ~rom differing ~1 , , ' ~ ......

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vertical elevations of said front and rear wheel assemblies, and wherein each of said wheel assemblies includes walking beam members located on opposite sides of said torque tube members, said walking beam members being mounted for movement about a common pitch axis, and whee~s mounted adjacent the respective enas vf the walking beam members.
Another aspect of the invention r~lates to an elongate vehicle which is adapted to traverse off-road terrain and which comprises, in combination: an elongate, generally horizontally extending bed frame, first and second elongate members disposed in spaced-apart and generally end-to-end ~-- relationship to one another, support means attached to said bed i :
frame and supporting said elongate members in said relationship for os~illation about their respective longitudinal axe~, said .
axes being spaced from, and extending generally parallel to, :
said main beam, such axes defining a roll ax.is, first and second :
spaced-apart wheel suspension assemblies being attached, respectively, to said first and second elongated members for oscillation therewith, and a differential disposed between the :
spaced-apart ends of said first and second elongate members, said differential comprising spaced-apart coaxially alignea bevel gears affixed to said first and second elongate members :~
and 2 planetary gear means meshing with said alignea gears to :
produce controlled and oppositely directed oscillation of said -~
fir~t and second elongated members relative to one another, .
said planetary gear means being selectively fixed rotationally with respect to said bed frame by adjustable means, whereby said :
bed frame may be adjusted and level~d to the left or right side independently of the forces resulting from differ~n~ verti~al 30 elevations of said first and second wheel assemblies and wherein each of said wheel assemblies includes walking beam m~mbers located on oppos~te sides of said first and se~ond elongate ~;

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~LIQ 56~73 members, said walking beam members being mounted for movement about a common pitch axis and wheels mounted adjacent the respective ends of the walking beam members.
A further aspect of the invention relates to a self-propelled vehicle adapted for use over roadless terrain, said vehicle comprising, in combination, an elongated bed frame, a front wheel assembly pivotally mounted on said frame to permit ~-pivotal movem~nt of said wheel assembly about a longitudinally ~:~
extending roll axis, a similarly mounted rear wheel assembly, and a roll control means intarconnecting said wheel assemblies with each othex and with said frame such that the frame is proportionately rotated about its roll axis by the rotation of said wheel assemblies relative to each other, said elongated bed ` frame being operatively connected to said front and rear wheel . .
a~semblies by springless mounting means, said roll control :: :
means comprising tor~ue tube members affixed to respective wheel .:. :.
assemblies,.said torgue tuba members extending towards each other longitudinally of sai~ bed frame and gear means ......... -interconnecting adjacent ends-of-said torque tube.members, . - ~.
whereby relative rotation of one tub~ member causes an equal .
and opposite rotation of the other tube member, said gear means being selectively fixed rotationally with respect to said ~:
bed ~rame by adjustable means, whereby said bed fxame may ~ .
be adjusted and leveled independently of the forces resulting ..
fro~ differing vertical eleYAtions of said front and rear wheel a~semblies, and wherein each of said wheel assemblies i~cludes independent walking be~m members located on opposite side6 of ~
~ai~ torque tube members, said walking beam members being : :
~ m~unted for independent movement about a common pitch axis, .
30 whereby one of said walking beam members can pitch independently ..
1 of ~aid opposite sid~ walking beam member~ and wheel~ mounted ... .:
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In accordance with yet another aspect, thP invention .
relates to a self-propelled off-road vehicle having an :
elongated main ~rame element extending the length of the vehicle and at least one casing containing power transmission ..
elements seeured to said main frame element in depending relationship thereto, the improvement comprising a high :-~
mobility mount.ing mechanism for four wheels separately driven ~rom said transmission elements consisting of: :
(1) a rigid support frame formed with a central aperture therein surrounding said transmission case and having opposed laterally projec~ing arm portions;
means for pivotally mounting the central portion of said support frame to said main frame in depending ..
relationship thereto for movement about a horizontal roll axis .
that is parallel to and below said main frame, whereby said . arm portions of.the support frame are freely movable .
concurrently but oppositely in a transverse vertical plane relative to said main frame member:
. 20 t2) a pair of walking beams respectively.having their medial portions pivotally s~cured to said arm portions ~, of said rigid frame for movements in vertical planes .
~^ respeotively parallel to said roll axis;
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(3) a ground engaging wheel both steerably and :~:
rotatably mounted on each end of each walking beam member; and .

(4~ power transmission means continuously : :~
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interconnecting each said wheel with said power transmission ~
. elements contained in said ca~ing. . : .
Thase advantacJes and other advantages and objects ...
will become more apparent when the following description is read with reference to the accompanying drawings. : ;
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1056~73 1~
BRIEF DESCRIPTION OF DRAWINGS
Figs. 1, 2 and 3 show a side elevation view, a front view and a plan view respectively of a preferred embodiment of the invented ~ehicle.
Fig. 4 is a perspective view of the rear section of the vehicle with parts broken away to show the suspension system of the rear quad wheel assembly.
Fig. 5 is a sectional side view of the rear quad wheel assembly taken along lines 5-5 of Fig. 6 showing in phantom lines a wal~ing beam member and its associated drive mechanism in maximum pitch position.
Fig. 6 is a sectional plan view taken along lines 6-6 ~. -of the rear quad wheel assembly shown in Fig. 7.
Fig. 7 is an enlarged sectional view taken along lines 7-7 of Fig. 3.
; Fig. 8 is an enlarged sectional view taken along lines 8-8 of Fig. 1 showing details of the platform dumping and tilting mechanism.

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~(~5~873 ~ 3553 1 Fig. 9 is an enlarged sectional view taken along lines 2 9-g of Fig. 8 with parts broken away, primarily showing 8 interior details of the roll control mechanism.

4 Fig. 10 is a sectional view similar to that of Fig. 7 ~ but showing the wheels of the ront and rQar wheel assemblies in 6 maximum roll positions.
Fig. 11 is a relatively laryer scale, partially sectioned side view of the rear wheel assembly transfer case taken along ~ lines ll-ll of Fig. 7.
lo Fig. 12 is a partially sectioned plan view of the transfer 11 case taken along lines 12-12 of Fig. 7.
12 Fig. 13 is a,partially sectioned side view of the 18 front wheel assembly transfer case showing interior details of 14 its upper or power input portion and a dog clutch loc~ing the power input shaft to the wall of the t:ransfer cas~.
lG Fig. l~ is a front view of t:he upper portion of the transfer case of Fig. 13 principally showing the exterior portion c 18 of the dog clutch.
lS Fig. 15 is a partially schematic plan view of the mechanical portion of the steering subsystem for the xear quad 21 wheel assembly with the mode control in the conventional steering .:
~ ~ 82 position and the wheels in a straightforward position.
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28 Fig. 16 is a view similar to Fig. 15 but with the steering components and wheels in a left-turn position.
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26 Fig. 17 is a view similar to Fig. lS but with the rnode 2G control and wheels in the e~treme right oblique position.

27 Fig. 18 is a partially schematjc plan view o~ the rear ~8 quad wheel asscmbl~ of Fig~ 15 illustrating the hydraulic portion 29 of the steering subsystem.

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I ' M-13553 -~568~3 1 DETAILED DESCRIPTION OF INV~NTION
2 The vehicle illustrated in the drawings is a transporta-8 tion vehicle such as one used for forwarding tree lengths from a 4 harvest.ing area in a forest to a landing adjacent to a road.
8 Referring particularly to Fig. 1-3 of the drawings, it will be 6 seen that the vehicle 20 i.s comprised of bed frame assembly 21 7 including load-carrying cradle assen~lies 22 adapted to carry a 8 plurality of tree lengths 23. Fron~ and rear quad wheel assemblies ~ 24, 26 are attached to the bed frame assembly 21 by journals so : .
10 as to be pivotally movable laterally with respect to the longi- , ' 11 tudinal a~is of the vehicle. A roll control means 28 interconnects ` -12 the quad wheel assembli'es wi.th each other and with the bed frame :
18 assembly so as to control their relative positions during operation. , 14 Preferably an engine unit 30 is located at tne rear end of the ., vehicle, and an operator's cab 31 is located at the front end.
1~ , The illustrated bed frame assembly 21 comprises an elon~
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17 gated tubular bed frame structure 32 extending lengthwise along ';

18~he center line of the bed. The bed frame structure 32 which ' ~

,~ 19 serves as the backbone of the vehicle may be a cylindrical tube ` ~ ':

` 20 made of front and rear sections 34, 36, which are identical or. ~ ..
, . ,21 interchangeable. The tubular sectlons may be bulkheaded, such as ,' , ~ . . .
22 at their ends 37, to provi~e fuel and hydraulic fluid stora~e i8 tanks (see F1g. 9). A~ plurality of bed cross beams 38t 39, 40, 24 41 extends laterally outward from the bed frame structure to form . 2~ the bases for the load-carryi.n~ cradles. Upright side s~akes 44 ,,.
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2~ are provided on the outer ends of the cross beams. The stakes, 27 along~;one or both sicles, may be releasably mounted to permit. side~

~8 ways dumpin~ of the load by tiltin~ the bed frame assemb].y 21.
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In the drawings it will be noted that the front and rear quad wheel assemblies 24, 26 are almost identical to one another so, for the sake of ~revity, the similar portions will be described with respect to one of them only. Accordingly, attention is directed to Fig. 4-7 of the drawings wherein the details of the rear quad wheel as~embly 26 are illusf r~ted.
; Basically, the elements of this assembly can be divided into two functional gr~ups, namely, those that relate to the drive mechanism for supplying power to the-four wheels, and those that relate to the suspension system for supporting the bed frame structure centrally between its four wheels. -~
The wheel suspension system includes a pair o~ "Y"
shaped yoke members 46, 47 respectively having a pair of arms 48~ 49 that extend outwardly and downwardly over opposite sides of the power transmission or clrive gear transfer case 50.
At the lower ends of these arms walking beams 52, 53 are rockably attached by bushings in their mid-sections to coaxially ~ : .
aligned shafts 55, 56 extending laterally with respect to the roll axis. For ease of descriptionr the common rocking axis of .
the walking beams will be deno~ed as the pitch axis. Wheel-modules 58, 59 are mounted on respective flanges 60, 61 located on the outer ends of each walking beam. In the preferred ~- embodiment the wheel modules are equipped with low pressure tires, e.g., 5-10 pounds per sguare inch and the wheel modules ; .
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are mounted such that a straight line between the pair of wheel axes of a walking beam runs beneath its pitch axis. Intermediate : .
portions 62, 63 lying between the ends and midsection of each walking beam are recessed inwardly, giving the walking beams a generally "W" shape in the plan view. ~his provides steerage clearance between the tires and the walking beams. In the illustrated embodiment, the clearance is suffi~ient to provide ~or -turning 30 to either side from straight forward.

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The upper or shoulder portions 64, 65 of the yoke members 46, 47 are rigidly joined together by two pairs of generally diamond-shaped flange plates 66, 67 thus forming a rigid frame with a central aperture. One method of ]oining the shoulder sections together is to form coaxially aligned right cylinder sections 70, 71 along the top of the shoulders, insert the cylindrical sections in holes bored in the corresponding pairs of flange plates and weld the cylindrical sections to the flange plates. The rectan~ular opening in the xigid frame between the shoulders 64, 65, and plates 67 allows the top of ~ -the transfer case 50 to protrude through the opening a distance that is sufficient to permit alignment of the top shaft axis in the transfer case with the drive line axis and the centers of the ~-flange plates. Each pair of 1ange plates has a hollow bearing shaft insert 72 which spans the space be~ween the cent~rs of the plates, thus forming a roll axis journal. Two of these journals are provided for each quad wheel assembly, and they are positioned so as to longitudinally straddle the center of the transfer ;~
case. A cor~esponding number of bearing members 74, 75 are affixed to the underside of the ~ed frame beam by means of pillars 76, 77. With this structural arrangemen~, the rotational axis of the quad wheel assemblies is parallel ~o the longitudinal axis .` , . .
_^ of the bed frame beam and is located directly beneath it~
Alternatively, the rotational axis of the quad wheel assemblies could be made coincident with the bed frame structure axis by providing bearing means in the top portions of the suspension -~
structure gear cases and using cylindrical portions of the bed ~rame structure as journals. In such an altexnativ~ e~bodiment, . ; .
the drive line may be located below the roll axis. Abutment means 78, 79 on pillars 76, 77 are provided to limit the extent of angular movement of each quad wheel assembly about its roll : ,. . .
axis.

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105t;87;5 The relative angular movement of the quad wheel 1.
assemblies with respect to each other and to the bed frame ¦.
assembly 21 is regulated by the roll control means 28 that causes the bed frame assembly to be rotated proportionately, 1: :
preferably one-half of the total angular displacement between the front and xear quad wheel assemblies. Angular displacement :
between the quad wheel assemblies occurs during operation on uneven terrain where the ground under the front qua~ wheel - ..
assembly is laterally and oppositely inclined to the ground under the rear quad wheel assembly, such as might oc~ur while the vehicle is traversing a ditch at an angle. The roll control l~
means illustrated in Fig. 9 is a bevel gear differential ~ :
assembly comprising pinion gears 82, side gears 84, 86 and ~ .
; housing 90. This differential assembly is mounted below the bed frame structure 32 by means of brackets 91, 92 and is rotatable therein but is normally held in a fixed rotational ~ ~.
; position with respect to the bed frame assembly. The side gears ...
84, 86 are splined on adjacent ends of torque tube members :
94, 95, which extend in opposite ~irections respectively to tha front and rear quad wheel assemblies where their remote ~ .
ends are bolted to the flange.plates 66 of the suspension yokes, ..
:for example, see the remote end of tube 95 (Fig. ~ ..

. Accordingly, any relative sidewise tilting or rolling .

' ~ of a quad wheel assembly will cause its torque tube member and :: side gear to be rotated, thereby rotating the pinion gears which in turn cause the opposite side gear, its torque tube and quad ; whe21 assembly to be subjected to a xotational force in.the ..

. opposite direction and, since the other wheel assembly is in .~:~

. engagem~t with the ground and cannot move, the end result is .~ :

that the annular carrier for the pinion gears, hence the b~d : -, , .:
. frame, is rotat~d about the roll axis an amount proportional ..
; to the gear rat1o, hence causing a relative rotation of the other .-quad aæsembly wi~h respect to the bed frame structure. One of the ,~
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~.~5~873 advantages of a vehicle equipped with the above-described suspension and roll control means is tha~ when a wheel is deflected upwards by a sidewise rolling of a wheel assembly, there is a proportionate upward displacement of the corresponding side of the platform asse~bly~ Thus for the same maximum rollg a vehicle so equipped may be slung 50 per cent closer to the top of the wheels than a vehicle not so equippeda Referring to Fig~ 8~ preferably the differential assembly housing 90 is adjustably locked to the crossbeam 40 of frame assembly 21 by a hydraulic cylinder and a piston means 98 in such a manner as to permit the steady state level of the bed frame assembly to be selectively changed~ For exa~ple, the bed frame assembly could be adjusted to a level position, if desired, when the vehicle is being operated on the side of an inclLne.
The hydraulic and piston means may also be used to tilt the bed `
frame assembly to an extreme angular position~ as is shown in -~
phantom lines on the drawing for dumping a load.
The vehicle drive train begins with an engine 100 ` which is preferably mounted on the rear end of the bed frame -~
structure 32 (see Fig. 1). A multispeed transmission 102 having forward, neutral and reverse positions is provided to transmit power from the engine through the main drive shaft 104, extending beneath the bed frame stsucture to the input member 106 of the rear transfer case 50 (see Fig. 11), thence forwardly by means of succeeding drive shafting to the front transfer case ` 51. Preferably, the axes of the input m~mber 106 and all succeeding drive shafts forward of it are coincident with the roll axis and are maintained in alignment with each other. In the illustrated embodiment these succeeding dri~e shafts are rotatably and concentrically supported within the torque tube members.

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One end of the input member 106 for the rear transfer case 50 i5 flexibly coupled to the main drive shaft 104 and the other end i~ integrally connected to the housing 110 of an interquad wheel differential assembly gear mechanism ~see Fig. 11). ~he side gear 112 towards the front of ~he differential is splined on a forwardly extending tubulax shaft :~
114 which carries the primary input gear 116 for dri~ing the ~
housing 118 of a first-stage di~ferential 120 of the rear I ~ :
transfer case. The other side gear 122 is splined on a :
countershaft 123 that extends forwardly ~hrough the hollow ;: :
spider 121 of the differential gear assembly housing 110 .
and then t~rough the cen~er of tubular shaft 114 to a shaft ::-coupling 124 outqide the trans~er case 50. ~
~he input ~haft ~5 (Fig. 13)for the front transfer case takes ,~; :
its power frcm an intermediate drive s~ft 126 coupled between it and the aforementioned countershaft 123. The center portion of this input shaft 125 carries a driv~a gear 128 for driving the housing 130 of a first-stage differential of the front : transfer ~a~e. Thi~ drive gear i8 rotatably mounted on the :
~20 input shaft and ha~ a dog clutch ace 132 on i~3 ~orward end .: for seleotive engagement with a shiftable dog clutoh member ::.
~. 134 splined on the forward end of the input ~haft. ~n th~
_- oppo~lte side of the shiftable mem~er 134 is a second dog :
clu~c~ face 135 afixed to the interior wall of the transfer ~
ca~e. ..
During o~f-road use when the tractive effort of both , quad wheel as~emblies is requiredt the ~hiftable clut~h .
; member i~ positioned in engagement with the clutah face 132 on the driv~ ~ear o~ ~ e front tr~nsfer ca~e, thus lock~ng .
` 30 the ~put ~haft and drive gear together. In this pos~tion the .-dxive train supplies power e~ually to both tran~fer ~ases :

rough the interquad w~eel d~f~erential in the rear transfer .', . ,'' ~ --10- : -' ~3 .''',-. ' , ~ L~56873 case. When the vehicle is being operated on a road surface and the tractive effort of the front wheel assembly is not required and increased speed becomes important, the shiftable clutch member may be positioned into engagement with the clutch face 136 on the transfer case wall. This locks the input shaft 125 against rotation along with all of the preceding drive line ~;
components back to and including the side gear 122 of the interquad wheel differential. Locking the one side gear 122 of the differential causes the other side gear 112 and the components dri~en by it to be rotated at twice their normal speed, thus providing a convenient means for doubling the -vehicle's high~ay speed. When the drive train has been shifted into this latter state, the front quad wheel drive is released and becomes free-wheeling.
Considering the individual wh~eel drives of each quad wheel assembly and beginning with the first stage differential 120, the succeeding elements o both the front and rear transfer case drives are identical and will be described primarily with reference to the rear gear transfer case 50 shown in Fig.
11. In brief, the first stage differential drives a pair of second stage differentials which in turn drive tow wheels each to provide balanced power distribution to the four wheels of the quad wheel assembly. The differential housing 118 of the first stage differential 120 is mounted on a master shaft 140 which has its ends supported on bearings 142, 143 located in Opposite ends of the transfer case. Its side or output gears 146, 147 are mounted respectiYely on coaxial tubular shafts 1~8, 150 which are, in turn, rokatably supported concentrically on ~` the master shaft 140. Drive gears 151~ 152 affixed to the si~e gear shafts mesh with driven gears 154, 155 affixed respectively ` around the differential housi~gs 160, 161 of a pair of second stage differentials 164, ~65. ~hese differential housings are coaxially and rotatably mounted on al~gned secondary master ~(~5~87~
shafts 166, 167 which extend inwardly from bearings 168, 169 on opposite sides of the transfer case to centrally located bearings 170, 171 supported by a rib section 172 on the vertical center line of the transfer case. The second stage differential 164 at the front end of the transfer case 50 on ~-the left bide of Fig. 11 distributes power to the two front wheels of the quad wheel assembly, while the second stage differential 165 at the rear end of the transfer case ,- 1 `~`;'' "' -: ' distributes power to the two rear wheels thereof. For ease of description, ~he drive components related to the forward l ~ -diffPrential 164 have been given even reference numbers and those related to the rearward differential 165 have been given odd reference numbers. The side gears 174, 175 on the outer sides of the two differentials 164, 165 are splined on the outer ends of the secondary master shafts 166, 167. Splined on the inner ends of these shafts are corresponding spur gears 178, -:
179. Between the side spur gears on each shaft 166, 167 are the other or inner side gears 180, 181 of the two differentials.
These inner side gears 180, 181 havle inwardly extending hub sections 182, 183 which are concentrically and rotatably mounted on their respective shafts 166, 167 and have spur gears 186, 187 splined on their innermost ends.
;~ As is best shown in Fig~ 12, the two even-nl~ ered gears ~-186, 178 driven by the second stage differential 164, in the forward half of the transfer case, drive spur gears 190, 192, respectively, for the left and right front wheels of the quad wheel assembly. Similarly, the two odd-numbered gears 179, 187 driven by the second stage differential 165, located in the rearward half of the transfer case, drive spur gears 197, 199, respectively, for the left and right rear wheels. These last ~."..
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, ~56873 four gears 190~ 192~ 197~ 199 of the gear train are affixed respectively to rotatable output shafts 200, 202, 207, 209 with-in the transfer case.
Each of the four output shafts is flexibly connected to an exterior drive shaft 21n by means of a constant velocity joint 212. A right angle drive mechanism 214 is connected to the outer end of each exterior drive shaft by means of a splined universal joint 21~ (see Figs. 4 and 5). Each wheel is driven by a shaft 218 extending laterally from the right angle drive.
Accordingly~ balanced driving power is supplied to each of the four wheels of both the front and rear quad ~heel assemblies.
~n antislip or positive drive means is provided to lock -~
all differentlals when the traction conditions between the wheels and the ground are such that one of the wheels breaks traction and begins to spin relatively freely. This positive drive means includes a series of hydraulically operated clutches which lock at least two of the three elements of each differential to each other, thus eliminating relati~e rotation between the output shafts of the differentials. Basically, each clutch comprises a -, 20 series of annular clutch disks with half of the disks splined on one differential member and alternate disks splined on another ifferential member~ In a free running position~ these clutch disks are spaced apart slightly sub~ect to being forced into firm non-slipping contact with each other by a hydraulically operated annular piston. The clutch 220 in the upper left part of the tra~sfer case in Fig. 11 is capable of locking together the two output shafts ll~ 123 of the interquad wheel differential that supply power respectively to the rear and front quad wheel assem- ~i blies. Alternate clutch disks 221 are splined on a drum 223 ;

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1~56873 which is, in turn, splined to the shaft 114 that drives the input gear 116 of the rear transfer case. ~e other half of the clutch disks 226 are splined to an interior drum 228 affixed to the out- -put shaft 123 that transmits power to the front quad wheel assembly input gear. An annular piston 230 is contained in an annular cylinder 232 in the face portion of the interior drum 228.
An acti~ating hydraulic system line 234 com~unicates with the cylinder via an aperture 236 in the wall of the transfer case.
The first stage differential 123 is supplied with dual clutches 237~ 238 of similar construction which serve to lock both of the output shafts 148~ 150 to the differential housing 118. Functionally~ only one clutch is needed to achieve a lockup~
but two clutches are provided here to balance the dynamic loads and provide increased clutch capacity. Anmllar hydraulic pîstons 241~ 242 are contained in annular cylinders on the sides of the inpu~ gears 151, 152 which drive the differential housings 160, 161 of the second stage differentials 164, ]L65. Alternate clutch disks 245, 246 are splined on each of bhe hubs of these input gears, while the remaining half of~the clutch disks 247, 248 are splined on the internal surfaces of drum section 249~ 250 extending outwardly from the sides of the differential housing 118.
-` Each of the second stage differentials has a clutch 252 or 253 wberein the alternate clutch disks 254 or 255 are ` respectively splined on the inner surface of a drum member 258 or i~ 259 affixed to the master shaft 166 or 167. The other half of j the clutch disks 260 or 261 are splined on an outer surface of a drum member 264 or 265 integrally connected to the differential housing 164 or 165. All of the clutches are activa~ed simul-', taneously by the same hydraulic system.
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, 68~3 The steering system illustrated in part in Figs. ~
15-18 provides an added degree of maneuverability to the vehicle~ -and thus enhances its utility. Basically, the illustrated steering system has at least two opsrational modes, one being a conventional Ackerman steering mode and another being an oblique travel modeO Since the component parts and functional features are substantially the same for the front and rear quad wheel assemblies, a complete understanding o~ the steering system can be gained from a detailed description of only one subsystem, namely, the subsystem 270 for the rear quad wheel assembly 26.
Each of the four wheels of the rear quad wheel assembly 26 is steerably connected to its respective walking beam 52, `~
53 end by means of a knuckle joint 272 designed for driven wheels ~see Fig7 6). Rigidly affixed to each wheel ad~acent to the ; knuckle joint is a steering arm 274 (see Figs. 15-18)o A linear actuator~ such as a hydraulic cylinder 275 and piston 276~ is -connested to the steering arm 274 and to an ad~acent portion 277 of the wheel suspension system so that relative movement of the piston ln either direction from a center or neutral position causes a corresponding turning movement of the wheel to the right or left. Flexible hydraulic lines 278, 279 run from opposite ends of each cylinder 275 to centrally located control Yalves 280 carried by a shiftable mode control plate 282.
Preferably, the control valves 280 are closed center, three-posi- -tion~ four-way~ center biased valves connected to the pressure manifold 286 by pressure line 284, and to the reservoir by return .: -` line 285 of a central hydraulic accumulator system ~see Fig~o18)~ - `
The valves are carried in parallel pairs along opposite sides of a plate 282 by means of four;parallelogram lever arms 290~ 291, : .. .. .
2~2, 293, which are pivotally connected by respective pintles ~ ~

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~L~5~373 300, 301, 302, 303 located adjacent to the four corners of the -plate 282. The two lever arms 290, 291 near the rear end of the plate are bell crank levers that have the free ends of adjacent legs connected together by a tie rod 304~ The other legs of these bell crank levers 290, 291 e~tend laterally from respective sides of the mode control plate 282. Each of these lateral legs carries the rearward ends of the bodies of two oppositely disposed control -valves 280 attached thereto by means of pivot pins. The forward ends of the valve bodies are likewise pinned to their respective -lever arms 292, 293 located at the forward end of the mode control plate 282. A parallelogram is formed on each side of the plate ; by the valve bodies and their connected lever arm sections. '~
The outer valves of both pairs of valves are spaced a greater distance from the lever pintles than the inner valves. ~ `
As a result, the outer valves move a greater distance than the inner valves when the levers are pivoted about their pintle axes.
This causes the wheels controlled by the outer valves to be turned more than the wheels controlled by the inner~ost valves. The outer valves of the rear quad wheel assembly control the rear pair of wheels, whereas the outer valves of the front quad wheel assembly control the front pair of wheels~ leaving the remaining two pairs of wheels to be controlled by the innermost valves~of ,, each subsystem. Preferably the relative spacing bet~een outer ~-~ and inner valves and the distance from the innermost valvesJto i their pintles ~n the sub~ystem are selected so that Ackerman : .: .
steering is achieved, i.e~, throughout the turning range the .. . .
plane of each wheel remains substantially perpendicular to its .
respective radius line drawn from a common point located along ~ a line that is perpendicular to the longitudinal axis of the : ~ 1~ '.' ,. . .

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~0~i6873 vehicle and through the center of the vehicle. In the illus-trated vehicle the maximum ~urning angle for the pairs of wheels at the front and rear ends of the vehicle is approximately 24-30 and for the two centrally located pairs of wheels is about 9-11 (see Fig. 16).
One of the lever arms at the forward end of plate 282, for example lever arm 293, is extended inwardly from its pintle 303 to a point above the longitudinal center line of the bed frame structure 32 where it is connected to the end of a reciprocable rod 306 of a linear actuator 308. The body of this arm actuator is anchored on the mode control plate 282.
Reciprocation of the rod 306 in either direction from its neutral position causes the interconnected lever arms and control valve -bodies to be moved dorrespondingly in unison. Since the valve spools of the control valves 280 are independently connected by push-pull caale means 310 to the steering a~ms 274 on the wheels~
they do not initially move with the valve bodies. Their move-ment is dependent upon movement of the steering arms so that when a steering movement is initiated~ the spoolsl are relatively dis-placed from their closed center position. Elydraullc fluid under ; pressure then flows through the vaIves to the steering cylinders ~ 276 and continues to flow until the wheels are turned sufficiently .~ : . .
to cause the feedback push-pull cable 310 to reposition the valve - . . .
spoo1s back to their closed center positions in the valve bodies.

' The oblique travel steering capability is simply : :
, accomplished by shiftably mounting the mode control plate 282 ; on a pair of parallel track members 312 extending along the sides '~ of the bed frame structure. A linear actuator 314 mount~d on ~ the bed frame structure 32 is used to position the mode control :~' '''' ~-, . .-,. .,~, , ' ' :
1 .

::~.. : : , : .: :- . . .: .:. . . ; : ; . .

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~56~373 .. .
1 plate at a location along the track members which corresponds 2 to,the desired oblique travel angle. In Fig. 17 the mcde 8 control plate 282 is positioned in the maximum rig.ht oblique 4 position. Under normal conditions the mode control plate is i .
6 centered between the rearward or right oblique position as shown 6 in the drawings and a forward or le~t oblique position. By 7 cycling the plate from one extreme position to the other while }
~ simultaneously causing the vehicle .to travel back and forth, the 9 vehicle can be displaced laterallv. These oblique and lateral 13 movements are particularly important when the vehicle is traversing 11 an area where the ground loses its support strength after being ~.
12 traversed by a limited number of loaded wheels. In the oblique r"
,18 travel mode the rear wheels travel over ~resh areas alongside 14 the travel path o~ the preceding wheel~ ~
1~ While this invention has been described with reference '' ~' 1~3 to a forwarding vehi.cle for transporting substalltially full- 5,':"
17 length cut trees, it is to be understood that th~ vehicle chassis " '' 18 can be used for many other purposes, particularly where superior '':-ls;off road.mobility is a requisite. Accoxdingly, it is intended ~ .;
ao that the scope of the i.nvention is to be limited pximarily by ,;. ', 21 the appended claims. ,. ,. :
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Claims (31)

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

1. A self-propelled vehicle adapted for use over roadless terrain, said vehicle comprising, in combination, an elongated bed frame, a front wheel assembly pivotally mounted on said frame to permit pivotal movement of said wheel assembly about a longitudinally extending roll axis, a similarly mounted rear wheel assembly, and a roll control means interconnecting said wheel assemblies with each other and with said frame such that the frame is proportionately rotated about its roll axis by the rotation of said wheel assemblies relative to each other, said elongated bed frame being operatively connected to said front and rear wheel assemblies by springless mounting means, said roll control means comprising torque tube members affixed to respective wheel assemblies, said torque tube members extending towards each other longitudinally of said bed frame and gear means interconnecting adjacent ends of said torque tube members, whereby relative rotation of one tube member causes an equal and opposite rotation of the other tube member, said gear means being selectively fixed rotationally with respect to said bed frame by adjustable means, whereby said bed frame may be adjusted and leveled to the left or to the right side independently of the forces resulting from differing vertical elevations of said front and rear wheel assemblies, and wherein each of said wheel assemblies includes walking beam members located on opposite sides of said torque tube members, said walking beam members being mounted for movement about a common pitch axis, and wheels mounted adjacent the respective ends of the walking beam members.

2. An elongate vehicle which is adapted to traverse off-road terrain and which comprises, in combination: an elongate, generally horizontally extending bed frame, first and second elongated members disposed in spaced-apart and generally end-to-end relationship to one another, support means attached to said bed frame and supporting said elongated members in said relationship for oscillation about their respective longitudinal axes, said axes being spaced from, and extending generally parallel to, said main beam, such axes defining a roll axis, first and second spaced-apart wheel suspension assemblies being attached, respectively, to said first and second elongate members for oscillation therewith, and a differential disposed between the spaced-apart ends of said first and second elongate members, said differential comprising spaced-apart coaxially aligned bevel gears affixed to said first and second elongate members and a planetary gear means meshing with said aligned gears to produce controlled and oppositely directed oscillation of said first and second elongate members relative to one another, said planetary gear means being selectively fixed rotationally with respect to said bed frame by adjustable means, whereby said bed frame may be adjusted and leveled to the left or right side independently of the forces resulting from differing vertical elevations of said first and second wheel assemblies and wherein each of said wheel assemblies includes walking beam members located on opposite sides of said first and second elongate members, said walking beam members being mounted for movement about a common pitch axis and wheels mounted adjacent the respective ends of the walking beam members.

3. A self-propelled vehicle adapted for use over roadless terrain, said vehicle comprising, in combination, an elongated bed frame, a front wheel assembly pivotally mounted on said frame to permit pivotal movement of said wheel assembly about a longitudinally extending roll axis, a similarly mounted rear wheel assembly, and a roll control means interconnecting said wheel assemblies with each other and with said frame such that the frame is proportionately rotated about its roll axis by the rotation of said wheel assemblies relative to each other, said elongated bed frame being operatively connected to said front and rear wheel assemblies by springless mounting means, said roll control means comprising torque tube members affixed to respective wheel assemblies, said torque tube members extending towards each other longitudinally of said bed frame and gear means interconnecting adjacent ends of said torque tube members, whereby relative rotation of one tube member causes an equal and opposite rotation of the other tube member, said gear means being selectively fixed rotationally with respect to said bed frame by adjustable means, whereby said bed frame may be adjusted and leveled independently of the forces resulting from differing vertical elevations of said front and rear wheel assemblies, and wherein each of said wheel assemblies includes independent walking beam members located on opposite sides of said torque tube members, said walking beam members being mounted for independent movement about a common pitch axis, whereby one of said walking beam members can pitch independently of said opposite side walking beam member, and wheels mounted adjacent the respective ends of the walking beam members.

4. A vehicle according to claim 1 wherein said torque tube members are coaxially aligned and concentrically disposed with respect to said roll axis.

5. A vehicle according to claim 1 wherein drive train shafting is concentrically contained in said torque tube members.

6. A vehicle according to claim 1 wherein said wheel assemblies each include four rubber-tired wheels mounted in pairs on walking beam members located respectively on opposite sides of said assembly, said walking beam members being mounted for rocking movement about said common pitch axis.

7. A vehicle according to claim 1 wherein said pitch axis is below said roll axis.

8. A vehicle according to claim 1 wherein said pitch axis extends through the center of said walking beams and lies above a line drawn between the axes of the paired wheels.

9. A vehicle according to claim 1 wherein each of said wheels is steerably mounted and the walking beams have a "W" shaped configuration.

10. A vehicle according to claim 6 wherein each of the four wheels of each wheel assembly is driven from a central gear transfer unit containing a plurality of differentials and having four output shafts.

11. A vehicle according to claim 10 wherein said front and rear wheel assemblies each include a gear transfer case containing a first stage differential gear unit, a pair of second stage differential gear units driven by said first stage unit, each of said second stage differential gear units driving two of said four wheels, and the first stage differential gear units of said wheel assemblies are driven by another differential gear unit.

12. A vehicle according to claim 1 further including steerable front and rear wheels and a two-mode steering mechanism whereby in one mode the wheels may be selectively turned to an oblique travel position with the planes of the wheels remaining parallel to one another.

13. A vehicle according to claim 12 wherein said mode control mechanism includes hydraulic control valves mounted on parallel lever arms pivotally connected to a carrier.

14. A vehicle according to claim 12 wherein said mode control mechanism includes a linear actuator for reciprocating said carrier between right and left oblique steering positions, and another linear actuator for pivotally moving said lever arms in unison between right and left turn positions.

15. A vehicle according to claim 1 wherein each of said wheels is steerably mounted on the walking beam members and an Ackerman-type steering means is provided.

16. A vehicle according to claim 2 wherein said differential is disposed generally midway between said wheel suspension assemblies.

17. A vehicle according to claim 2 wherein said elongate members are disposed vertically below said main beam.

18. A vehicle according to claim 2 wherein said oppositely directed oscillation of said first and second elongate members is equal in angular amount relative to said main beam.

19. A vehicle according to claim 2 wherein each of said first and second wheel suspension assemblies comprises at least one pair of spaced-apart wheels rotationally attached thereto, the axis of said main beam lying in a vertical plane which extends generally equidistant between the wheels in each pair thereof.

20. A vehicle according to claim 19 and comprising steering means to attach each of said wheels to said assembly to provide controlled oscillation of said wheels about spaced apart, vertically extending axes, whereby Ackerman-type steering of said vehicle may be achieved.

21. A vehicle according to claim 19 wherein at least one of said first and second wheel suspension assemblies comprises first and second pairs of spaced-apart wheels and wherein said walking beam members are attached near their respective longitudinal midpoints to one of said elongate members for oscillating movement independently of one another in limited arcs and in generally vertically extending parallel planes lying parallel to and on opposite sides of said elongate member, and- wherein the wheels are rotationally attached to the walking beams at spaced-apart points on opposite sides of the points of attachment of the walking beams to the elongate member.

22. A vehicle according to claim 20 wherein each of walking beams is non-resiliently attached to said elongate member and wherein said wheels are non-resiliently attached to said walking beams.

23. A vehicle according to claim 22 wherein each of said wheels is a rubber-tired wheel of the low ground pressure, high flotation type.

24. A vehicle according to claim 21 and comprising steering means to attach all of the wheels of said four pairs thereof to said walking beams to provide controlled oscillation of said wheels about spaced-apart, vertically extending axes, whereby relatively short turning radius Ackerman-type steering of said vehicle may be achieved.

25. A self-powered vehicle according to claim 21 and further comprising: power source; a gear case at one of the wheel suspension assembly for transmitting power to at least one of the pairs of wheels attached to said assembly; and power transmission means for transmitting power from the power source to the gear case.

26. A self-powered vehicle according to claim 25 wherein the central power source is attached to an end of said main beam and wherein the power transmission means comprises a first gear case at the wheel suspension assembly more remote from the power source for transmitting power to at least one of the pairs of wheels attached to said assembly, and a second gear case at the other of the wheel suspension assemblies for transmitting power to at least one of the pairs of wheels attached to the other of said assemblies and for selectively transmitting power to the first gear case.

27. A self-powered vehicle according to claim 26 wherein said first and second elongate members are tubular in cross-section and wherein said power transmission means further comprises drive line means extending from said power source to said second gear case and from said second gear case to said first gear case through said first and second elongate members and through the differential disposed therebetween.

28. A self-powered vehicle according to claim 26 wherein the first gear case is adapted to selectively transmit power to both of the pairs of wheels at such wheel suspension assembly and wherein the second gear case is adapted to selectively transmit power to both of the pairs of wheels at such wheel suspension assembly.

29. A vehicle according to claim 2 which is adapted to carry a load of elongate, generally horizontally extending objects, and further comprising: generally U-shaped and normally upwardly facing load-carrying means to said main beam in a position disposed above said elongate member and extending generally parallel thereto.

30. A vehicle according to claim 29 wherein said elongate generally horizontally extending objects are harvested tree stems and harvested trees.

31. A self-powered vehicle according to claim 20 which is shorter in overall length than the length of objects which said vehicle is adapted to carry and further comprising:

a power source attached to an end of said main beam at an elevation beneath said main beam; means for transmitting power from said power source to at least some of the wheels of at least one of said wheel suspension assemblies; and an operator cab attached to the other end of said main beam at an elevation beneath said main beam.