Three-axle vehicle
l l Apr. 8, 1975 3.397.896 3/1968 180i]: X 3.5061179 4/l97ll 4/l97ll l l THREE-AXLE VEHICLE Madler et al.  
 Isa/23 3.5(l7t5lI McKee et al. 3.680163 8/1972 inventor: Francois Durand. lllh BOtllc\Lll&#39;Ll Carnot 78. Le \esinet. Ywlines. France 22 Filed: Feb 20 1974 Primary k&#39;xumim&#39;rLeo Friaglia Arlurm&#39;y. Agent. or Firm-Michael St Striker {Zll Appl. No.1 444.241  
 I57] ABSTRACT A three-axle vehicle having two steerable axles lo- [30] Foreign Application Priority Data 73 N333 eated on either side of a central asle is disclosed Each steerahle axle is respectively associated with an end France Feh.  
 ISO/8| R; 298/17 R; chassis and pivoted about a vertical axis provided thereon. so as to steer the vehicle. A main chassis is oriented with respect to each end chassis so as to dis- [5|] Int.  
 Field of SearchiWW...  
 lxo/xl R 8L5; [go/31 tribute the loading uniformly amongst all three axles.  
 298/17 R 21 R Cooperating sets of pivotahle joints and connecting memhers which interconnect each steerable axle to the central axle. as well as interconnectin chassis to all three axles; are also disclosed g the main References Cited UNITED STATES PATENTS ISO/23 X 9 Claims. 6 Drawing Figures 1099:1610 7/l9b3 Sheehan...  
 THREE-AXLE \I&#39;IHICLF.  
 BACKGROL&#39;ND OF l&#39;HIi INYENIION The present invention relates in general to multiple axle \ehicles and has particular reference to an improved design of three axle vehicles vvherein tvvo steerable axles are disposed on either side of a central axle. These vehicles are special-purpose ones and may be used notably for public works or for transporting heavy loads.  
  A number of vehicles of this type have already been proposed in tlte art. Hovvevcr. in these knovvn construd tions the load distribution among the six \vhecls as a function of the ground profiles and uncvennesses de pends mainly on the flexibility of the suspension elements of the vehicles. Besides. in these prior art vehi cles the necessary pivotal connections between the axles. about the longitudinal center line of the vehicle. are provided by means of horizontal pivot shafts and these are compulsorily heavy and cumbersome.  
  It is therefore the essential object of the present invention to provide a vehicle of the same general char acter but so designed that the loads are evenly distributed among the three axles. and wherein the simplest means are used for pivoting the various axles about the longitudinal center line of the vehicle.  
  To this end. the vehicle according to this invention is based on the combination ofthe characteristic features listed hereinafter:  
 a. each steerable axle is pivoted to an end chassis about a vertical axis. at least one of these end chas sis may be oriented vvith respect to the main chassis in order to distribute a more uniform loading among the axles. the tvvo end chassis being adapted to absorb the steering reactions.  
 b. each end or steerable axle chassis is connected to the central axle by means of a pair of forks disposed one above the other and having different orientations or angular settings:  
 . the spaced or spread-apart ends of the lovver connecting fork are pivoted. directly or indirectly. to the central axle shaft and the apex of this fork is pivoted by means of a Universal joint or ball-and socket joint to the corresponding end chassis at a point located in the median longitudinal plane of the vehicle, betvveen the central axle and the corresponding end or steerable axle. and at a distance affording an even distribution of loads among these two axles;  
 d. the spaced ends of the upper connecting fork are secured or pivoted to the corresponding end chassis, and the apex of this fork is pivoted directly or indirectly to the central axle shaft by means of a universal joint or ball-and-socket joint. at a point lying substantially in the median longitudinal plane of the vehicle;  
 . the main. load-supporting chassis is supported by a pair of substantially vertical supporting bars having their upper ends pivoted to said main chassis and their lower ends supported by the relevant apices of the lovver connecting forks. respectively,  
  When it is deemed necessary to avoid vertical dynamic effects. the pair of supporting bars carrying the main chassis may consist of elastic rams, in order to constitute an elastic load suspension.  
  According to another feature characterising the vehi cle of this invention. a stabilizing frame structure is pro- \ided on one side only of the central a\lc for connecting this central axle to the main load carrying chassis. said stabiii/ing frame being pivoted at one end to the central axle shaft and at the other end about an upper hori/ontal axis parallel to said central axle shaft and substantially coincident vvith the axis ofthe pivotal connection betvveen the corresponding supporting bar piv oted to the main chassis.  
  With the arrangement according to this invention. the three axles of the vehicle are pivotally interconnected. but the pivotal and connecting means provided to this end are so designed and disposed that the loads carried by the main chassis are evenly distributed among the six vvhccls of the which. this distribution being substantially independent of the load suspension means:  
  Besides. the relative pivotal movements of the a\les about the longitudinal center line of the vehicle are oi tained by using simple ball-and-socket or universal joints. the imaginary axis interconnecting these oints constituting the pivot axis of one axle in relation to the other tvvo.  
  Due to the prov ision of the abov c mentioned stabili/ ing frame the load carried by the vehicle assumes the same lateral inclination as the central axle. Hovvev er. other means may be contemplated for stabili/ing the load both laterally and longitudinally. so that it can follovv the lateral inclination of one of the steerable end axles of the vehicle.  
  Other features and advantages characterising the vehicle according to this invention vvill appear as the fol lovving description proceeds vvith reference to specific forms of embodiment thereof given by way ofexample and illustrated diagrammatically in the attached dravv ings. in which:  
  FIG. 1 is a perspective ievv of a first embodiment of the vehicle of this invention;  
  FIGS. 2 and 3 are perspective vievvs shovving t\vo modified embodiments of this vehicle;  
  FIG. 4 is a fragmentary section taken on a larger scale along the line lY lv of FIG. 1;  
  FIG. 5 is a fragmentary elevational vievv of a detail of the embodiment of FIG. 3. and  
  FIG. 6 is a section taken along the line \I-\&#39;l of FIG. 5.  
  In the form of embodiment illustrated in FIG. 1, the three-axle vehicle according to this invention comprises two steerable axles l and 2 disposed on either side of a central. non steerable axle 3. These steerable axles I, 2 are pivotally mounted in tvv o end chassis 4 and 5 independent of the main chassis 6 adapted to carry the load to be transported by the vehicle. To this end. the end steerable axles l. 2 are pivoted to vertical pivot pins 7 carried by these end chassis 4. 5. respectively; the steering of these end axles I, 2 may be controlled through any suitable and known means. for example by means of hydraulic cylinder-and-piston units reacting between the steerable axles l. 2 and the end chassis 4. 5 respectively.  
  Each end chassis 4. S is connected to the central axle shaft 3 by means of a pair of forks 8. 9 disposed above each other and inclined in opposite directions.  
  The spaced or spread apart legs IO of the pair of lovver forks 8 provided on either side of the central axle shaft have their ends rotatably mounted on this axle shaft. The apex of each fork 8 comprises a yoke 11 pivoted to the inner end of an arm 12 rigidily carried by the inner face of the corresponding end chassis 4 or 5. This pi\ otal mounting comprises a ball-and-socket joint 13 secured to a pi\ot pin 14 interconnecting the two arms of yoke II and movable in a bearing Unsecured in a suitable opening of said arm [2 lsee Fl(i. 4).  
  lt should be noted that the center of this hallatndsocket joint lies in the longitudinal median plane ofthe \ehicle. Besides. this center is located between the central role shaft 3 and the corresponding steerable avle l or 2. at a suitable distance ensuring an even distribtition of the loads among these axles.  
  The spaced ends l of the pair of upper connecting forks 9 are pivoted to the upper portions of the corre&#39; sponding end chassis 4 and 5. respecti\cl To this end. the inner face of each end chassis 4. 5 carries a pair of strap 16 each engaged by one end of the upper corinecting fork 9 which is pi\oted therein by means of a corresponding hori/ontal pivot pin [7.  
  Besides. the pair of upper connecting forks J ha\e their apices pi\otally connected to the central axle shaft 3. To this end. this central avle shaft 3 comprises on either side a pair of straps engaged by the narrow end portions ofthese forks in which the are pivoted by means of a corresponding pair of ball-and-socket joints each carried by a pivot pin 18. These ball-and-socket joints will thus lie in the longitudinal median plane of the \ehicle.  
  It should be noted that the imaginary axial line interconnecting the ball-and-socket joints I3 and [8 of the apices ofthe two superposed connecting forks disposed on a same side is coincident with the pivot axis of an end chassis 4 or 5 in relation to the central axle shaft 3.  
  The main chassis 6 supporting the load bears on a pair of substantially vertical supporting bars 1) disposed in the median longitudinal plane of the \ehicle. as shown. The upper end of each bar 19 is pivotally connected to a strap 20 rigidly carried by the underface of the main chassis 6. The lower ends of these bars 19 carry in turn corresponding straps 2| pivotally con nected to the apices of the lower connecting forks 8. respectively. as shown. This pivotal connection is obtained by means ofa pivot pin 14 extending through the corresponding ballaind-socket joint 13 (see FIG. 4).  
  hi the form of embodiment illustrated in FIG. 1 the vehicle comprises a stabilizing frame comprising a pair of parallel arms 23 interconnected by bracing members 24. These arms 23 are disposed on either side of the ve hicle and bear with their lower ends on the central axle shaft 3 by means of bearings 25. The upper ends of these arms 23 are pivoted to pivot pins 26 inside straps 27 provided to this end at one end of the main frame 6.  
  The purpose of this stabilizing frame is to constantly keep the main chassis 6 in the same lateral inclination conditions as the central axle 3.  
  As already explained in the foregoing. the original design ofthe threeaxle vehicle according to this invention is advantageous in that the axles are allowed to oscillate independently of one another while affording an even distribution of the loads without resorting to the elastic component elements of the suspension system for this purpose. Therefore, this even distribution of loads is obtained irrespective of the ground unevennesses.  
  The elastic load suspension may be obtained by providing elastic rams or cylinder-and-piston units for constituting the \ertical supporting bars I) at both ends of the main chassis 6.  
  In the modified form of embodiment illustrated in FIG. 2 the vehicle construction is based on the same general principles as the ehicle shown in FIG. I; therefore. identical or corresponding parts are designated by the same reference numerals but these bear the exponent letter (1.  
  However. in this example other connecting means are substituted for the stabilizing frame 23 of the preceding embodiment for constantly maintaining the main chassis (m supporting the \ehicle load in the same lateral inclination as one of the steerable axles. namely the axle 241.  
  To this end. the corresponding end chassis 41! carries at its upper portion a pair of brackets 28 rigid therewith which are pivoted to a pair of horizontal pivot pins 29 in corresponding straps 3O underlying the corresponding end or cross-member of chassis 6a.  
  In this respect it may be noted that the two pivot pins 29 are substantially aligned with the pivot pin 20a by which the supporting bar 19!! is pivotally connected to the corresponding end of chassis (m.  
  The pair of straps 30 are spaced as far as possible from each other so that the main chassis (m follows the changes in cant of the steerable axle 2a. In this case. only the supporting bar 19:: disposed under the opposite cnd of the main chassis can be constructed as an elastic cylinder-and-piston unit acting as a suspension device for the load transported by the vehicle.  
  hi the alternate form of embodiment illustrated in FIG. 3 of the drawings the corresponding vehicle has the same general arrangement as in FIG. I. and the corresponding component elements are designated by the same reference numerals bearing the exponent b.  
  However. this vehicle departs from the preceding ones by a number of points.  
  Thus. the spread-apart ends of the upper connecting forks 9/) provided on either side are rigid with the corresponding end chassis 412 and 5/). instead of being pivoted thereto. On the other hand. the apices of these forks 9/1 are not pivoted directly to the central axle shaft 3i;v In fact. each upper fork 9b. is pivoted at its small end about a pivot pin 18b carried by a strap 3] carried in turn by a cross member 32 rigid with the arms of the corresponding lower connecting fork 8b. However. these pivotal connections are still located in the median longitudinal plane of the vehicle and very close to the central axle shaft 3h.  
  Another modification resides in the substitution of a pair of relatively heavy posts 19b, 190 for the vertical supporting bars 19 of FIG. 1. At its lower end, the post 19!; is rigid with the corresponding lower fork 8b and with the top portion 11b thereof which is pivoted through a pivot pin 14!) to an arm 12b rigid in turn with the corresponding end chassis 4b.  
  At its upper end this post 1% carries a pair ofintegral lateral arms 33 having pivoted to their outer ends the main chassis 6b by means of balland socket joints 34. To this end. the lower face of this main chassis 6b carries a pair of straps 35 registering with said joints and having fitted therein corresponding pivot pins 36 engaging the corresponding joints 34.  
  The ball element 34 is movable in a concave bearing 37 carried by a vertical fork 38 formed integrally with the outer end of the corresponding arm 33 (see FIGS. 5 and 6). The trunnion-forming ends of pivot pin 36 are movable with a certain play in notches 39 formed in the side members of strap 35.  
  The post 190 provided at the opposite end comprises like post 19/) a pair of integral rigid arms 33. at its upper end. for supporting b v means of ball-and-socket joints 34 the relevant end of the main chassis. Preferably. each joint 34 comprise locking means responsive to a fluid-actuated cylinder 40 secured under said main frame 6/2. The piston rod of this c \linder 40 carries a locking fork 41 of which the horizontal prongs are adapted to engage passages formed in the side members of the corresponding strap. underneath the pivot pin 36.  
  The lower end of the other post I90 is pivoted as in the preceding case to the top of the lower corresponding connecting fork 8L. However. this pivotal mounting is not located just plumb to the one provided at the top of the same fork on the corresponding end chassis 511. la fact. the pivot pin 22c connecting the lovver end of post 190 to the top llt&#39; of fork 8c is somewhat off-set in relation to the axis of pivot shaft l-k of the ball-andsocket joint connecting this fork end to the arm 12c carried by the corresponding end chassis 511. &#39;l&#39;hus. the pivot pin 22c is located betvveen the central axle shaft 3b and the axis of hall 130.  
  The stabilizing frame 23 provided in the embodiment of FIG. I is replaced b v a pair of side bars 23/ having their lower ends 25/) pivotallv mounted to the corresponding ends of the central axle shaft 311. The upper ends ofthese bars 23/) are rigid with the ends ofthe pair of arms 33 carried bv the upper end of post 19b.  
  Besides. a pair of lifting jacks 42 are provided at the top of each supporting posts 1911 and 19c. These jacks 42 partially engage the relevant posts l9b. 19c with a certain clearance. their lower ends being pivoted within these posts about a cross pin 43.  
  At their upper ends. these jacks 42 carry a ball-andsocket joint 44 engaging a strap rigid with the lower face of the main chassis 6h. Thus. by actuating these jacks 42 it is possible to tilt the chassis 6h about the pins 36 on one or the other side, as necessarv.  
  Of course. many modifications and variations may be brought to the specific forms of embodiment shown and described herein without departing from the basic principles of the invention as set forth in the appended claims. as will readily occur to those coversant with the art.  
 What I claim is:  
  l. Three-axle vehicle comprising a main chassis, two end auxiliary chassis. of which at least one is independent of said main chassis. a central non-steerable axle, two steerable axles provided on either side of said central axle. and pivotally mounted to an end chassis. a pair of forks disposed one above the other with opposite inclinations and operatively connecting each end chassis to said main chassis. the spread-apart ends of each lower connecting fork being rotatably mounted about the central axle and the apex of said lower fork being pivoted by means of a universal joint to the corresponding end chassis at a point located in the median longitudinal plane ofthe vehicle and between said central axle and the corresponding steerable axle. at a suitable distance for evenly distributing the loads among these two axles; while the spread-apart ends of each upper connecting fork are connected to the corre sponding end chassis. and the apex of said fork is pivoted to said central axle bx means of a universal joint at a point lving substantialb in the median longitudinal plane ofthe vehicle: a pair ofsubstantialh vertical bars supporting said main chassis. said bars being disposed in the median longitudinal plane oftlie vehicle and hav ing their upper ends pivotall connected to said main chassis and their lower ends adapted to bear on the apex of each lower connecting fork.  
  2. Three-axle \ehicle according to claim 1. in which. at their lower ends. said vertical bars supporting the main chassis carrving the \ehicle load are pi\oted to the apex of the lower connecting fork on the corresponding side.  
  3. Three-axle vehicle according to claim 1. in which one of said supporting bars has its lo er portion rigidlv connected to the apex of the corresponding lovver con necting fork.  
  4. Three-axle vehicle according to claim I. in which said pair of vertical bearing bars are constructed in the fortn ofelastic jacks to constitute an elastic suspension system for the load-supporting main chassis.  
  5. Threeaxle \ehicle according to claim 1. in which on one side onl v. in relation to the central axle said central axle is connected to the main chassis supporting the vehicle load by means of a stabilizing frame having the maximum rigidity and width. the ends of the sides of said stabilizing frame being pivoted to said central axle on the one hand and about a pi\ot pin parallel to the central axle and passing substantialh through the centre of the upper pivot pin of the corresponding bearing bar. on the other hand.  
  6. Three-axle vehicle according to claim I. in which one of the end chassis has bracket-like lateral extensions disposed as far as possible from and on either side of. the longitudinal center line of the vehicle. said main chassis being pivoted to the upper ends of these brackets by means of pivot pins disposed at the maximum permissible distance from said center line of the main chassis and disposed in a plane parallel to said central axle which contains likewise said central bearing bar on the corresponding side. the imaginary line interconnecting the axes of the upper pivot pins of said bearing bar and said stabilizing pivot pins being substantiallv parallel to said central axle.  
  7. Three-axle vehicle according to claim 1. in which the upper end of each supporting bar comprises two arms extending on either side thereof and having pivoted to their outer ends strap means rigid with said main chassis by means of pivot pins. each associated with suitable locking means adapted to lock each pivotal connection.  
  8. Three-axle vehicle according to claim 7, in which a lifting jack is interposed between the upper end of each supporting bar and the main chassis.  
  9. Three-axle vehicle according to claim 7, in which in the locking means associated with each pivot pins comprise a fluid-actuated cylinder and piston unit adapted to lock the corresponding pivot pin.  
  l l l