FR2843078A1 - All terrain vehicle for passengers produced by adapting riveted chassis, comprises engine propelling driving road wheels differential boxes through central transmission box and transmission shafts - Google Patents

Abstract

A chassis (1) which consists of longitudinal girders with riveted cross members is adapted with bodywork (2) to take passengers in seats (22). The vehicle has a driver's cabin (21) and an engine (3) which delivers power to a centrally located transmission box (13). Pairs of motor wheels (14,15) are driven from universal joints (131,132) via shafts and differentials and a variety of hydraulic controls are provided. An Independent claim is also included for : A method of reconstructing a riveted chassis to make an all terrain passenger vehicle including braking and transmission control systems and lengthened wheel base

Description

All-terrain transport vehicle produced by adapting a chassis

  The present invention relates to a utility vehicle, in particular for transporting people or bulky goods, obtained by adaptation and re-industrialization of a riveted chassis and its kinematics of

transmission to the wheels.

  To make all-terrain utility vehicles, it is known to build or adapt a body, steering controls and an engine on a load-bearing chassis, supplied complete with the suspensions, the wheelsets, the complete braking circuit, and all the drive kinematic chain. This kinematic chain is then provided to receive energy from an assembly comprising a motor, a gearbox and a clutch, by mechanical coupling means such as a shaft or a fluted sleeve. This energy is then transmitted to the drive wheels by one or more drive shafts, via one or more

  several differentials and possibly a transfer case.

  In the case of an all-terrain vehicle, the qualities of adaptation of the vehicle to different terrains are mainly determined by the qualities of the chassis itself and of the kinematics used for driving its drive wheels. These qualities depend in particular on the operating modes of the drive kinematic chain, and on the capacity of the wheels to all remain in contact with the ground whatever the profile. The transmission must in particular be able to continue to drive the other drive wheels when a drive wheel no longer encounters grip on the ground. This transmission uses a transfer gearbox, to have an additional reduction ratio to combine with the ratios of the main gearbox coupled to the engine. The qualities of the chassis depend in particular on the operating mode of the suspensions, that is to say on the travel and the independence of the devices provided to support the chassis on each of the wheels and absorb variations in height from the ground under these wheels. . Thus, a chassis, the wheels of which can all rest at the same time, at respective non-coplanar contact points, on a ground having significant differences in level will benefit from good qualities.

grip and crossing.

  When the goal is to make a utility all terrain vehicle, in small quantities or in small quantities, for example for transporting goods or people, it is common to use a complete chassis as described above, to adapt a group to it engine and bodywork adapted to needs. In such a case, the choice is therefore limited to the different types of complete chassis existing on the market, which therefore limits both the possibilities of adaptations specific to a particular need and the level of

  all-terrain performances accessible for a limited cost.

  The object of the present invention is to provide a utility vehicle base adapted to specific needs and produced for a limited cost, while benefiting from good qualities of all-terrain behavior, and in

  good security and reliability conditions.

  This object is achieved by an all-terrain motor vehicle base using a drive wheel drive kinematic chain comprising a transfer box anchored to the chassis between at least two drive trains each carrying at least two drive wheels, this transfer box using transmission shafts to drive at least these drive trains in rotation, each carried by a rigid drive axle whose wheels retain substantially the same axis of rotation, the transmission and suspension kinematics allowing these two drive axles to be angularly movable. one with respect to the other along the longitudinal axis of the vehicle, or along an axis transverse to the vehicle, or both, thus authorizing simultaneous contact with the engine ground of the two drive trains at at least four non-coplanar points on the ground, characterized in that on the one hand it rests on a chassis, the structure of which is made from elements of strand steel between them, and on the other hand it comprises at least one braking system using a hydraulic or pneumatic braking control pressurizing at least two braking circuits, each of these circuits being sufficiently independent of the others to be able to carry out the braking d '' at least one wheel in the event of complete failure of any element located downstream of this braking control (master cylinder) and on the other braking circuit. According to one feature, the drive kinematic chain drives the drive wheels of at least one drive axle via a differential carried by this axle and driving at least two wheels of this axle located on each side of the chassis, this differential comprising a first mode of operation o these drive wheels can rotate at different speeds from each other, and a second mode of operation o the difference between the rotational speeds of these wheels is limited so that all of the wheels drive units of this bridge receive a drive torque

not bad.

  According to one feature, each drive wheel of at least one drive axle is driven by an output shaft of a reduction gear carried by the axle and driven from the differential by an input shaft whose axis of rotation is located more

  higher than the axis of the output shaft by a determined distance.

  According to one feature, the part of the kinematic chain driving each drive axle comprises at least one gimbal coupling the transfer case to the transmission shaft driving this axle and allowing this shaft to take a variable angular position relative to the chassis, according to a

axis transverse to the chassis.

  According to one feature, at least one motor bridge supports the chassis by means of deformable suspension means in height located on each side of the chassis, this motor bridge being connected to the transfer case by elements capable of allowing a determined angular movement. not bad

  of this bridge relative to the chassis along the longitudinal axis of the vehicle.

  According to one feature, the vehicle base comprises a pneumatic transfer control circuit, controlled from a cockpit, and using actuation means to actuate at least one function of the transfer case, this pneumatic circuit making it possible to

  position this cabin regardless of the chassis geometry.

  According to one feature, the chassis is obtained from a so-called original chassis having an original length and provided with a drive kinematic chain adapted to this original length, the distance between the transfer case and at least one drive train being increased by a so-called extension length by interposition, between the transfer case and the bridge carrying said drive train, of one or more extension elements assembled by means of assembly to the elements of the original kinematic chain and ensuring

  continuity of training between these same original elements.

  According to one feature, the chassis is obtained by distancing at least

  minus one drive train on each side of the transfer case.

  According to a particular feature, the extension elements towards an engine axle comprise an extension shaft driven by the transfer case or by the original shaft coupled to this same transfer case, this extension shaft driving the differential of this axle or resulting in the original shaft coupled to this

same differential.

  According to a particular feature, the extension elements towards a motor bridge comprise an extension tube surrounding the extension shaft or the original shaft or both, this extension tube comprising guide means capable of keeping the radial position constant of this or these shafts, and being secured by means of assembly on one side to an upstream tube, surrounding the original transmission shaft or the extension shaft, and coming from the gearbox output gimbal transfer, and on the other side to a downstream tube, surrounding the original transmission shaft or the extension shaft and leading to the differential of this bridge. According to one feature, the transfer control means comprise: - a first pneumatic cylinder controlling the selection of a reduction ratio among several available in the transfer box; - A second pneumatic cylinder controlling the activation or deactivation of a so-called compensation device capable of causing the drive of a second motor bridge by the motor or by a first motor bridge when the wheels of this second motor bridge rotate at a speed lower than that of the first drive axle; a third pneumatic cylinder controlling the activation or deactivation of a so-called dog clutch device capable of coupling the rotation of the shafts within the transfer case

  transmission each driving an engine axle.

  According to one feature, the chassis, the vehicle base is used for

  make a vehicle intended for the transport of more than 5 people.

  The invention also provides a method for re-industrializing an all-terrain motor vehicle base comprising a chassis, the structure of which is made from steel elements riveted together and comprising a drive drive kinematic chain of sets of drive wheels, this kinematic chain comprising a transfer box anchored to the chassis between at least two drive trains, this base comprising, on each of at least two wheels, means for braking this wheel by a solid friction caused by a hydraulic or pneumatic thrust, characterized in that it comprises at least one of the following steps: - installation of one or more braking circuits until at least two braking circuits are obtained, each of these braking circuits being capable of transmitting pressure from a brake control to the braking means of at least one of the wheels, so that each of the braking circuits ge thus obtained is sufficiently independent of the others to be able to brake at least one wheel in the event of complete failure of any element located downstream of this braking control and on another of these circuits; installation of a pneumatic transfer control circuit, controlled from a cockpit and using actuating means to actuate at least one function of the transfer box, this pneumatic circuit making it possible to easily position the cabin independently of the position of the transfer case; - lengthening of the distance, known as the wheelbase, separating the axes of the drive wheels of two separate drive trains, the distance between the transfer case and the axis of the drive wheels of at least one of these drive trains being increased by a length called extension by interposition, between the transfer case and said drive train, of one or more extension elements assembled by means of assembly to the elements of the original kinematic chain and ensuring the continuity of the drive between these

same original items.

  The invention, with its characteristics and advantages, will emerge more

  clearly on reading the description made with reference to the accompanying drawings

  in which: - Figure 1 shows a simplified side view of a passenger vehicle using a chassis adapted according to the invention; - Figures 2a, 2b, and 2c respectively show a top view and side view of the structure of the chassis adapted according to the invention, and a partial view in cross section of the riveted assembly of two elements of this chassis; - Figure 3 shows a perspective view of a frame adapted according to the invention, with its drive kinematic chain; - Figure 4 shows a simplified transverse view of an engine axle of a chassis adapted according to the invention; - Figure 5a shows a schematic side view of the angular movement in pitch of a motor bridge carrying the chassis adapted according to the invention; FIG. 5c represents a schematic transverse view of the angular movement in roll of a motor bridge carrying a chassis adapted according to the invention; - Figures 6a, 6b and 6c show simplified side views of a chassis adapted according to the invention, in the original wheelbase version and in elongated versions by distancing one and two drive trains respectively; - Figures 7a and 7b respectively represent an extension tube and an extension shaft of an extension kit used to move a drive train from the transfer case during the adaptation according to the invention; - Figure 8 shows a symbolic diagram of the transfer control circuit installed on a chassis adapted according to the invention;

  - Figure 9 shows a symbolic diagram of the braking circuit.

  Before approaching the description of the invention, it is necessary to

specify the following concepts.

  In the present description, it will be understood that the capacities of a

  vehicles to be driven in all terrain include in particular the fact of having a ground clearance and a large suspension travel, as well as being able to have more than two driving wheels simultaneously and in particular to be able to continue to drive one of these wheels when one or more

  several other drive wheels have lost all grip on the ground.

  The vehicle presented in this description is in particular a

  all-terrain vehicle for public transportation. The specific adaptation possibilities sought and allowed by the method and the vehicle according to the invention however make it suitable for being used to make any all-terrain utility vehicle for loading, working, or tool holder, capable of

  correspond to the possibilities of this chassis once modified according to the invention.

  Such vehicles may for example include crane, site or breakdown vehicles, auger holders, cable unwinders,

  concrete mixers, cabin transporters or specialized modules.

  To obtain good qualities of behavior on varied grounds, a large and independent clearance of the different wheels is a major criterion. However, the elasticity or flexibility of the chassis itself can also bring additional advantages if it allows it to accompany the movement of the wheels, including in a non-coplanar deformation movement. However, in the majority of cases, the supporting frames are obtained by metallic elements welded together, in order to obtain a low weight and for reasons of cost and productivity. In addition, automobile chassis are generally designed to obtain good handling at medium or high speed on a road in good condition, since the risks incurred at such speeds directly affect passenger safety. Such chassis are therefore designed with the aim of exhibiting high rigidity, even if this is detrimental to low speed behavior on uneven terrain. In addition, the creation of a transport vehicle which can be specifically adapted to transport people or goods

  bulky is an industrially underdeveloped sector in an all-

  courses. However, such vehicles assume a long length without necessarily requiring a very high load capacity. According to national or regional, for example European legislation, the concept of passenger transport can be understood as applying to a number of passengers transported greater than five or ten. Vehicles specially adapted for this use have a number of seats, according to European standards,

  possibly for example from about ten to forty.

  On the current industrial market, it is clear that there are few complete chassis, if any, meeting current standards, in particular safety, and which can be used to make an efficient and economical all-terrain public transport vehicle. In addition, current safety standards include a number of requirements which would be difficult and costly to meet without using a complete chassis designed and

  manufactured homogeneously and with industrial means.

  Instead of seeking to use such a chassis, the invention proposes on the contrary to adapt, individually or in small series but according to industrial standards, a type of chassis already existing on the market and

  with the desired all-terrain qualities.

  A chassis called SUMB (for Simca Unic Marmon Boquet, registered trademarks), designed in the 1960s to make small military transport vehicles, still exists today in a certain number of copies in the fleet of vehicles of the French Army. This high-strength steel chassis has satisfactory crossing and payload characteristics for the desired vehicle, but insufficient dimensions and unsuitable for public transport and safety characteristics unsuitable for current standards, in particular

  to the standards of the European Economic Community.

  In fact, this chassis of two two-wheel drive trains has only a wheelbase of 2.90 m for an overall length of 5.10 m, which is insufficient to produce a means of public transport, by example of 24 places. In addition, this chassis uses four drum brakes controlled by a master through a single hydraulic braking circuit, which does not meet current standards requiring two independent braking circuits. On the other hand, the kinematics of this chassis allows a good adaptation of the running gear to the terrain, and is carried by a ladder-shaped chassis whose cross members are fixed on two beams by riveting. That is to say that the steel elements forming the structure of this chassis are assembled by rivets, consisting of solid metal rivets with one head passing through the plates to be assembled to be riveted on the side opposite their head by widening their end by mechanical deformation. Although difficult to implement and representing a greater weight, this technique gives the assembly

  flexibility which represents an advantage in all terrain and at low speed.

  This technique also ensures good reliability in assembly because the presence of multiple rivals independent of each other makes

  all unlikely to crack gradually, unlike a weld.

  According to the invention, the adaptation of such a riveted chassis and its original systems, braking and kinematics, to the needs of a vehicle for transporting people or bulky goods uses a certain

  transformation numbers which are described below.

  Thus, this adaptation is done according to a process, which includes one or more of the following steps: - Addition of an additional hydraulic braking circuit, or removal of all or part of the original circuit and replacement by

two independent circuits.

  - Possible extension of the chassis by cutting the side members and

  welding of an additional part.

  - Extension of the wheelbase by moving a train of driving wheels, or two trains, by dismantling the kinematics and interposing of extension pieces transmitting the driving forces. - Addition of a pneumatic control circuit for the transfer box functions, so as to make the positioning of the cockpit independent of the geometry of the kinematic chain, and to be able to position it at the front end of the vehicle while in

  retaining control of the controls of this transfer box.

  The adaptation of this chassis may also include the installation of a steering system with screw box and hydraulic assistance, comprising a hydraulic steering damper, as well as the replacement of the springs.

  original suspension by others of greater rigidity.

  FIG. 1 represents a vehicle according to the invention, comprising a body (2), mounted or built on a chassis (1) provided with an internal combustion engine (3) driving the kinematics of the chassis. The body (2) comprises a plurality of seats (22) for passengers, and a cabin (21) or cockpit located at the front of the vehicle, in a

  so-called advanced or semi-advanced position.

  In FIG. 3 is shown a chassis (1) of the SUMB type, mounted on four wheels (101, 102, 103, 104) which can be driven. As illustrated in FIGS. 2a, 2b, and 2c, this chassis comprises two longitudinal members (111, 112), with a "U" profile facing each other. These beams are parallel and assembled longitudinally to the axis of the vehicle by crosspieces (12). These cross members have at their ends parts (121) at right angles, which are contiguous to the web of the side members (111, 112) and assembled by a plurality of rivets (120). These rivels have an elongated part (1200), one end of which carries a head (1201). The elongated part crosses the square (121) of

  the cross member (12) and the beam of the spar (111) by two coaxial holes.

  The initially free end of the rivelon was then enlarged into a riveting head (1202) by mechanical deformation, for example by stamping or forging. Because several independent rivelons assemble the two plates by several independent holes, a possible new or old defect is unlikely to create a crack which could spread to the whole of the fixing between the crosspiece (12) and the spar ( 111). Similarly, the use of such non-welded intermediate parts leaves the two assembled parts with the possibility of slight deformations which allow the chassis

  greater flexibility in its overall structure.

  The chassis supports a transfer box (13) anchored substantially in the middle of the length of the chassis. This transfer box receives an engine torque from the engine-gearbox-clutch group by coupling means (131). This transfer box (13) transmits this engine torque by two

  gimbals (132,133) to the two sets of drive wheels (14, respectively 15).

  Each train of two driving wheels (103, 104) is organized in a rigid bridge (14) receiving the engine torque in a differential (141) from a transmission shaft guided in rotation and protected inside a tube (140 ) thrust, assembled to a similar tube (134) coming from the corresponding cardan (132). The differential (141) distributes the engine torque in a known manner between the two wheels of the bridge (14) to which it belongs, according to a free operating mode or a blocked operating mode. In the free operating mode, the differential freely distributes the torque between the two wheels, which allows them to turn at different speeds and minimizes internal stresses in the drive shafts between them, in particular along the path of the vehicle. In the blocked operating mode, the differential distributes the engine torque equally or according to a difference, called slip, limited, so that each wheel of the train remains even driven

  if the other turns freely without adhesion.

  Each wheel (103, 104) of this train (14) receives its engine torque from the differential (141) via a half-shaft rotating inside a transverse tube (142). This transverse transmission half-shaft drives the input shaft of a reduction gear (143) integral with the transverse tube (142), and the output shaft of which guides and drives the wheel (103). This reducer allows a reduction, and possibly a choice of reduction ratio among several, making it possible to further decrease the speed of rotation of the wheel, and therefore to increase its torque. The reducer output shaft (1432) has an axis parallel to that of its input shaft (1431), but located lower than this input shaft by a distance (e143). This arrangement places the axis of rotation of the wheel (103) lower than that of the half-shaft emerging from the differential (141), which increases the ground clearance under the differential and

  improves the vehicle's crossing capabilities.

  These bridges (14, 15) are of the type called gantry, and are made without welding and by forging according to a "Clark" process. They are able to support a load of 5000 kg, and are of the non-loadbearing type. Their total ratio is 6.75, with a differential bevel gear of 9x32 and wheel reducers of 18x34. The rear axle has a locking

  pneumatically controlled differential.

  Each bridge supports a part of the chassis in two regions located on either side of the longitudinal axis of the chassis and close to the wheels, by suspension means (145). These suspension means support the chassis by elasticity means, for example helical springs of a determined diameter, replacing the original springs so as to increase the payload of the vehicle compared to the original vehicle. These suspension means also comprise damping means connecting the bridge to the chassis and damping the oscillations transmitted from the ground to the chassis (1),

  for example telescopic or arm hydraulic shock absorbers.

  The rigidity of each bridge (14) around a substantially vertical axis is ensured by a triangulation, produced by a triangulation bar (144)

  connecting the push tube (134) to the end of each transverse tube (142).

  The entire bridge (14) is connected to the transfer box (13) by the thrust tube (134) which ends in a shell pivoting around the gimbal (132) of the box outlet corresponding to said bridge (14), forming thus a ball joint between the

deck and chassis.

  Each bridge (14) is connected to the chassis by two points, at the level of the suspension means, and a point at the center of rotation of its universal joint (132) at the outlet of the transfer case (13). This universal joint is mounted so as to allow its output shaft a certain angular movement around an axis transverse to the chassis and passing through the center of rotation of the universal joint. As illustrated in FIG. 5a, each bridge (14, 15) therefore has freedom of movement relative to the chassis (1) according to a rotation with a longitudinal axis, with a movement in both directions, of an angle (a141 ) determined. This travel is limited by the depreciation means or by

additional elements.

  In addition, each gimbal (132, 133) is designed to allow the thrust tube (134) which leads to the corresponding bridge a certain freedom of

  rotational movement around the axis of the drive shaft it houses.

  The suspension means (145) located on each side of said bridge (14) are

  designed to be able to operate independently from side to side. The entire bridge (14) therefore has freedom of movement in

  rotation relative to the chassis and around the axis of the drive shaft which drives. Each train (15, 14) of wheels (101, 102, respectively 103, 104) therefore has a combination of freedom of movement in rotation both around an axis transverse to the chassis and the axis of each shaft of transmission, which is not coplanar to it while being close to the longitudinal axis of the chassis in a vertical plane containing this longitudinal axis. Because of this combination, each of these trains therefore in fact has freedom of movement in rotation about a longitudinal axis to the chassis (1),

  according to a displacement of an angle (a142) determined not zero.

  As illustrated in FIG. 5b, this combination of rotations relative to the chassis (1) allows all of the wheels of the two trains to remain in contact with the ground at four points (SI, S2, S3, S4) determined not coplanar. When the condition of the ground requires it, this ability allows to keep a good grip, and at the same time to stabilize the balance

of the vehicle on such terrain.

  The transfer box (13) combines several functions of the kinematic chain which make it possible to improve the driveability of the vehicle in difficult terrain, or to provide mechanical elements when the driveability is not a problem. For this, this transfer box can operate according to several operating modes including a free operating mode, a compensated operating mode and a clutched operating mode. In the free operating mode, or normal position, only the universal joint leading to the rear axle is driven. In the clutch mode, or reduced position, a dog device also drives the gimbal leading to the front axle. In the compensated operating mode, the rear axle is driven, and a device comprising two sets of dog teeth with reverse teeth automatically drives the front axle as soon as its speed of rotation becomes lower than that of the rear axle, for example when the

  rear wheels have lost all grip and rotate freely.

  In addition, the mechanical energy of rotation received by the input coupling means (131) connecting this box to the motor unit can be transmitted according to several gear ratios. A so-called high speed report transmits this energy with little or no reduction, so as to allow a relatively high speed compatible with conventional road use, for example up to around 120 km / h. A report known as low speed transmits this energy with a lower speed of rotation in output, therefore also a higher torque, so as to be able to use the engine in its ranges of optimal uses, even at low speeds which are compatible with terrain difficult or obstacle clearance needs. This transfer case has two ratios, 1/1 and 1 / 2.025 and

  admits an input torque up to 250 m / kg.

  The different operating modes of this transfer box (13) can be turned on or off by the action of mechanical selectors accessible on this box. During the adaptation of this chassis, each of these selectors is connected to an actuator, for example a pneumatic cylinder (51, 52, 53). These actuators are then controlled from the control cabin (21) by a pneumatic circuit controlled by control means (211, 212, 213), which makes it possible to place this control cabin at a point distant from the transfer box without require the installation of a remote control linkage for these selectors. This cockpit, or an equivalent driving position, can thus be installed at the front end of the vehicle to leave the maximum volume in the space allocated to passengers or cargo. According to the terms of the different standards or legislations, this cabin can in particular be located in a position

  called "advanced", or "semi-advanced".

  An example of a pneumatic control circuit for the modes of

  operation of the transfer box (13) is presented in figure 8.

  When adapting this chassis, the modifications to the braking circuit intended to obtain improved safety compared to the original chassis include the addition of one or more oleopneumatic braking circuits, in addition to or in place of the circuit original. The braking means originally fitted to the wheels, for example drum brakes, are retained. The original circuit can possibly be kept and modified so as to control only two wheels instead of four, for example the two wheels (101, 104) located at the two opposite corners of the chassis or the two wheels of the same train. A new oleopneumatic braking circuit is then installed to control the other two wheels (102, 103). Another solution is to keep only the braking means on the wheels, for example drum brake plates, and to replace the entire braking circuit by two independent circuits, each managing a train of

wheels.

  Such a system comprising two independent circuits is described in FIG. 9. The braking means of each wheel comprise one or more wheel actuators (not shown), for example hydraulic cylinders or jacks, actuated by a master (62, 63) cylinder common to two wheels on the same train. Under hydraulic pressure supplied by the master cylinders (62, 63), the hydraulic wheel actuators apply pressure to a movable part of the wheel, for example a drum, by means of a part integral with the bridge which carries this wheel. , for example

  jaws fitted with friction linings.

  The master cylinder (62) controlling the actuators of the two wheels of the front train (15) receives pneumatic pressure by means of a pneumatic circuit (64) supplied by a compressed air reservoir of their own, the reservoir ( 66) front braking. In the same way, the master cylinder (63) controlling the actuators of the two wheels of the rear train (14) receives pneumatic pressure by means of a pneumatic circuit (65) supplied by a compressed air reservoir which is supplied to them. clean, the tank (67) of

rear braking.

  The supply of compressed air to each of these two pneumatic brake circuits (634,) is controlled by control means, called brake controls (61), for example a brake pedal actuated by the driver and mechanically actuating two valves. (611, 612) which each control the passage of compressed air in one of the two braking circuits (64, respectively 65). The two reservoirs (66, 67) of compressed air supplying these two circuits (64, 65) are maintained in pressure in a known manner by a compressor (680) associated with a desiccator (681) of air and a reservoir (682) of regeneration. These reservoirs are supplied by means of a protection valve (683) ensuring the independence of these reservoirs from one another, and vis-à-vis their supply by a non-return function. This valve (683) also controls an order of successive filling of the various tanks: first the front brake tank (66), then the rear brake tank (67) and finally the trailer brake tank (69) which allows also releasing the parking brakes

as described below.

  The braking system also comprises one or more trailer braking circuits (691), transmitting pneumatic pressure to the braking means of one or more trailers by means of pneumatic coupling means (693). These trailer brake circuits are supplied with compressed air by their own compressed air reservoir, the trailer brake reservoir (69), itself maintained in pressure in the same way as the two reservoirs (66, 67) front and rear braking. These trailer brake circuits (691) are supplied by the trailer brake reservoir (69) via a trailer control valve (692), receiving compressed air from the reservoir (69) by the through a circuit (690) common to all trailers. The passage of compressed air from the common trailer circuit (690) through each of the trailer brake circuits (691) is controlled by two taps (649, respectively 659) coming from the front (64) and rear ( 65). The trailer control valve (692) is arranged so that any one of these two taps (649, 659) is sufficient to control the braking of the trailer, even if the braking circuit of the other

bypass is defective.

  The braking system also comprises a pneumatic parking or emergency braking circuit (74, 75), transmitting a pneumatic pressure to two spring cylinders (72, 73) actuating parking braking means, included in the braking means described above or operating separately. These spring cylinders are kept loose when they receive air pressure, and any interruption of this air pressure releases the springs which then automatically apply

braking force.

  For use of the moving vehicle, these parking brake means receive pneumatic pressure from the trailer brake reservoir (69), via a parking brake circuit (70) comprising a non-return valve. (77). This pressure keeps the parking braking means released as long as the trailer tank (69) is under pressure. To apply the parking brakes (72, 73), the driver releases the pressure from the parking or emergency braking circuit (74, 75) by pressing the control valve (71). The same action can also release the pressure contained in a possible trailer parking brake circuit (not shown), by means of a line connecting the valve (692) of

  trailer control at the parking brake valve (71).

  The parking valve (71) makes it possible to select the following two operating modes: - In a normal operating mode, this valve supplies the parking brake circuits (74,) from a circuit (70) supplied directly by the trailer tank (69). This tap them

  thus transmits the pressure of said reservoir and keeps them loose.

  - In a parking mode, this tap (71) isolates the parking braking circuits (74, 75) from this circuit (70), and allows them to return to atmospheric pressure. This exhaust then leaves these

  parking brakes (72, 73) apply automatically.

  In the event of failure or insufficient pneumatic pressure in the circuit, the parking braking means (72, 73) are therefore no longer maintained and are applied automatically, thus performing a brake function.

rescue.

  Unlike the original chassis circuit, these two front and rear circuits therefore use totally different pipes and internal elements from one another, which makes them independent in their operation, at least for a certain time. Such independence allows that any failure of one of the two circuits does not prevent the vehicle from still having a certain braking capacity. This independence is an important criterion to guarantee a certain safety in the use of such a vehicle, and is essential to meet the standards in force in many countries or regions, and in particular within the

European Economic Community.

  The invention therefore provides the functions necessary for bringing such original chassis into conformity with current standards. This adaptation process is used in particular for compliance with the standards of the European Economic Community of original chassis

  military or not transformed into civilian vehicles.

  In a variant, the modifications to the braking circuit intended to obtain improved safety with respect to the original chassis may also include the addition of one or two additional hydraulic braking circuits in addition to or in place of the origin. The braking means originally fitted to the wheels, for example drum brakes, are retained. The original circuit can possibly be kept and modified so as to control only two wheels instead of four, for example the two wheels (101, 104) located at the two opposite corners of the chassis or the two wheels of the same train. A new hydraulic braking circuit is then

  installed to control the other two wheels (102, 103).

  Each of these two hydraulic braking circuits contains an incompressible fluid called hydraulic and receives hydraulic pressure from a master cylinder actuated by a mechanical control of the driver. This circuit transmits this pressure to the braking means of the wheels which it controls, that is to say to one or more actuators or hydraulic jacks which apply pressure to a movable part of the wheel, for example a drum, by the '' through an integral part of the bridge which carries this wheel,

  for example jaws fitted with friction linings.

  When adapting this chassis to the needs of a modern vehicle for mass transit or for transporting bulky goods, the dimensions of this chassis are often insufficient or

  unsuited to the specifics of these needs.

  The adaptation of this chassis can then include an extension of the very structure of the chassis. This elongation can be done by cutting the longitudinal members in one or more locations, to interpose therein an element (10) of structural extension fixed for example by a high resistance weld.

carried out in the factory or workshop.

  In order to maintain good balance capacities for the vehicle obtained, it may be important to also extend the wheelbase (E, FIG. 6a) of the chassis, that is to say the spacing of the wheels which support it. However, in the case of the SUMB chassis, all the wheels can be driven and are connected by transmission shafts of a determined length. The extension of the wheelbase therefore requires a modification of the whole of the

  drive kinematic chain.

  As illustrated in FIGS. 6a, 6b, and 6c, the invention therefore proposes moving a drive train, or both, relative to the central part of the chassis (1), where the box (13) of transfer. This modification of the vehicle base then makes it possible to lengthen the chassis without increasing the vehicle's angle of attack and flight. For each drive train to be moved, the adaptation then includes the interposition of new elements between the original elements transmitting the engine torque between a universal joint (131, 132) output from the transfer case and the differential (141, 151) of the bridge (14, 15) carrying the train

wheels to move.

  As illustrated in FIG. 7a, the tightness of the kinematics is preserved by inserting a push tube said tube (40) of extension between the

  tube (134) coming from the universal joint (132) and the tube (140) leading to the differential (141).

  This extension tube is assembled with each of the two original tubes by assembly and sealing means compatible with those which connected the original tubes to each other, that is to say bolts passing through two flanges protruding radially from each of the tubes and joined to one another along a sealing sealing peripheral surface. This assembly allows in particular a seal against snow and sand. For crossing a ford, the chassis thus modified can accept without special preparation a

1.20 m water depth.

  As illustrated in FIG. 7b, the continuity of the drive chain is preserved by interposing an additional transmission shaft, known as an extension shaft (41), between the original transmission shaft exiting the gimbal (132) transfer box outlet and driving the differential (141) of the corresponding bridge. This extension shaft (41) is coupled to the downstream end of the original shaft by coupling means, for example a sleeve (42) with internal grooves, compatible with the external grooves carried by the original shaft and similar splines carried by the extension shaft at its upstream end. At its downstream end, the extension shaft also carries grooves similar to those of the downstream end of the original shaft which allow it to be inserted into the differential coupling means (141) instead and place of the original drive shaft. The radial guidance of this extension shaft (41) is ensured by guide means carried by the extension tube (40). These guide means comprise for example a tubular bearing (43) with needle bearings mounted on a cylindrical bearing surface of the extension shaft. This additional bearing is held in the extension tube by a plurality of rubber toroids compressed between the wall

  internal of the tube and the external surface of the bearing.

  By using one or more extension kits (4) each comprising an extension tube surrounding an extension shaft, it is thus possible to simply produce different versions of different wheelbases, from the same original chassis. For an extension kit allowing the distance of a drive train from a distance of 0.60 m, it is for example possible to adapt an original chassis of length 5.10 m and wheelbase 2, 90 m in a version with a length of 5.70 m and a wheelbase of 3.50 m. By using such an extension kit on each side of the transfer box (13) to distance the two drive trains from 0, 60 m, it is possible to adapt an original chassis of length 5.10 m and d wheelbase 2.90 m in a version with a length of 6.30 m and a wheelbase of 4.10 m. It is of course also possible to distance one or two trains a greater distance from the transfer box, using for each several extension kits interposed one behind the other in the chain

drive kinematics.

  It should be obvious to those skilled in the art that the present invention allows embodiments in many other specific forms without departing from the scope of the invention as claimed. Therefore, the present embodiments are for illustrative purposes, but may be

  modified in the field defined by the scope of the appended claims, and

  the invention should not be limited to the details given above.

Claims (13)

  1. Base for an all-terrain motor vehicle using a drive drive wheel drive kinematic chain comprising a transfer box (13) anchored to the chassis (1) between at least two trains (14, 15) engines each carrying at least two driving wheels (101, 102, 103, 104), this transfer box using transmission shafts to drive in rotation at least these drive trains each carried by a rigid drive axle whose wheels retain substantially the same axis of rotation, the kinematics transmission and suspension allowing these two drive axles angular mobility with respect to each other along the longitudinal axis of the vehicle, or along an axis transverse to the vehicle, or both, thus allowing simultaneous contact with the ground and engine of the two trains (14, 15) engines at least four points (SI, S2, S3, S4) on the ground not coplanar, characterized in that on the one hand it rests on a chassis (1) whose structure is r made from elements of steel riveted together, and on the other hand it comprises at least one braking system using a hydraulic or pneumatic braking control pressurizing at least two braking circuits, each of these circuits being sufficiently independent of the others in order to be able to brake at least one wheel in the event of the complete failure of any element located downstream of this master cylinder and on the other braking circuit. 2. Vehicle base according to claim 1, characterized in that the drive kinematic chain drives the drive wheels of at least one engine bridge (14) by means of a differential (141) carried by this bridge and driving the at least two wheels (103, 104) of this bridge located on each side of the chassis (1), this differential comprising a first mode of operation o these driving wheels can rotate at different speeds from each other, and a second operating mode o the difference between the rotational speeds of these wheels is limited so that all the wheels   drive motors of this bridge receive a non-zero drive torque.   3. Vehicle base according to one of claims 1 to 2,   characterized in that each driving wheel (103) of at least one drive axle (14) is driven by an output shaft (1432) of a reduction gear (143) carried by the axle and driven from the differential (141) by an input shaft (1431) whose axis of rotation is located higher than the axis of the output shaft of a distance (e143) determined.   4. Vehicle base according to one of claims 1 to 3,   characterized in that the part of the kinematic chain driving each motor bridge (14, 15) comprises at least one gimbal (132, 133) coupling the transfer box (13) to the drive shaft driving this bridge and allowing this tree to take a variable angular position (a141) by   relative to the chassis (1), along an axis transverse to the chassis.   5. Vehicle base according to one of claims 1 to 4,   characterized in that at least one motor bridge (14) supports the chassis (1) by means of suspension deformable in height situated on each side of the chassis, this motor bridge being connected to the box (13 ) transfer by elements capable of allowing a non-zero determined angular clearance (a142) of this bridge relative to the chassis along the longitudinal axis of the vehicle.   6. Vehicle base according to one of claims 1 to 5,   characterized in that it comprises a pneumatic transfer control circuit, controlled from a control cabin (21), and using actuation means to actuate at least one function of the transfer box (13), this pneumatic circuit to position this cabin   regardless of the chassis geometry (1).   7. Vehicle base according to one of claims 1 to 6,   characterized in that its chassis (1) is obtained from a so-called original chassis having an original length and provided with a drive kinematic chain adapted to this original length, the distance between the box (13) transfer and at least one engine train (14, 15) being increased by a length called extension by interposition, between the transfer case and the bridge carrying said engine train, of one or more elements (40 , 41) extension assembled by means of assembly to the elements of the original kinematic chain and ensuring the continuity of the drive between these same original items.   8. Vehicle base according to one of claim 7, characterized in that its chassis is obtained by moving at least one engine train from   each side of the transfer case.   9. Vehicle base according to one of claims 7 to 8,   characterized in that the extension elements towards a motor bridge (14) comprise an extension shaft (41) driven by the transfer case (13) or by the original shaft coupled to this same transfer case, this shaft (41) extension driving the differential (141) of this bridge or driving the original shaft coupled with this same differential.   10. Vehicle base according to one of claims 7 to 9,   characterized in that the extension elements towards a motor bridge (14) comprise an extension tube (40) surrounding the extension shaft (41) or the original shaft or both, this extension tube comprising means (42) guide capable of maintaining constant the radial position of this or these shafts, and being secured by means of assembly on one side to an upstream tube (134), surrounding the original transmission shaft or l extension shaft, and coming from the universal joint (132) of the transfer case outlet, and on the other side to a downstream tube (140), surrounding the original transmission shaft or the shaft   of extension and leading to the differential (141) of this bridge (14).   11. Vehicle base according to one of claims 1 to 10,   characterized in that the transfer control means comprise: a first pneumatic cylinder (51) controlling the selection of a reduction ratio among several available in the transfer box (13); a second pneumatic cylinder (52) controlling the activation or deactivation of a so-called compensation device capable of causing the drive of a second motor bridge (15) by the motor (3) or by a first bridge (14) ) engine when the wheels of this second engine axle turn at a speed lower than those of the first engine axle; - A third pneumatic cylinder (53) controlling the activation or deactivation of a so-called dog clutch device capable of coupling within the transfer box (13) the rotation of the two transmission shafts (136) each driving a bridge (14, 15) engine.   12. Vehicle base according to one of claims 1 to 11,   characterized in that it is used to make a vehicle intended for the transport of more than 5 people.   13. Method for re-industrializing an original base of an all-terrain motor vehicle comprising a chassis, the structure (1) of which is made of elements (111, 11 2, 12) of steel riveted together and comprising a drive train drive train (14, 15) of drive wheels, this drive train comprising a transfer box (13) anchored to the chassis (1) between at least two drive trains, this base comprising, on each at least two wheels, means for braking this wheel by solid friction caused by hydraulic or pneumatic thrust, characterized in that it comprises at least one of the following stages - installation of one or more braking circuits up to '' obtaining at least two braking circuits, each of these braking circuits being capable of transmitting pressure from a braking command (61) to the braking means of at least one of the wheels, so that eachbraking circuits thus obtained is sufficiently independent of the others to be able to brake at least one wheel in the event of complete failure of any element located downstream of this braking control (61) and on another of these circuits ; - installation of a pneumatic transfer control circuit (5), controlled from a control cabin (21) and using actuating means (51, 52, 53) to actuate at least one function of the box (13) transfer, this pneumatic circuit making it possible to easily position the cabin independently of the position of the transfer box (13); - lengthening of the distance, called the wheelbase (E), separating the axes of the drive wheels of two trains (14, 15) separate engines, the distance between the transfer case (13) and the axis of the drive wheels of at least one of these drive trains being increased by a so-called extension length by interposition, between the transfer case and said drive train, of one or more extension elements (40, 41) assembled by means of assembly to the elements of the original drive train and ensuring the continuity of   training between these same original elements.