MODIFIED VEHICLE SUSPENSION

Abstract: A vehicle such as a trailer includes a vehicle body (10), a pair of ground wheels (26) and a suspension system (30) resiliently supporting the body (10) with respect to the wheels (26). The suspension system (30) is so dimensioned and positioned as to be actuable to alter the relative vertical positions of the ground wheels (26) and vehicle body (10) from a normal condition in which the vehicle is mobile to one in which, with a first extremity (24) of the vehicle body (10) supported in a raised position, the vehicle body (10) is inclined from said first extremity (24) to a lowered extremity (25) closely adjacent or in contact with the ground. The preferred suspension includes inflatable/deflatable air bags (38) having air supply lines (40) and acting between the vehicle body (10) and arms (32) which support the wheels (26).

Description: "MODIFIED VEHICLE SUSPENSION" TECHNICAL FIELD This invention relates to a vehicle suspension system which has particular, though by no means exclusive, application to trailer vehicles. BACKGROUND ART The normal method of transferring movable loads, such as other ' vehicles, to and from a trailer is by a temporary ramp arrangement positioned ' at the tail of the trailer. This can be quite difficult and cumber- some and may require additional hands to jockey the load over the top of ramp boards. In the case of, for example, a boat, it is necessary to back the trailer into the water so that the boat may be floated off the trailer or winched from the water onto the trailer. It is known to control the level height of a vehicle chassis above the ground by inflating and deflating an air suspension system of the vehicle. An example is to be found in Australian Patent Specifi¬ cation 458313, which discloses multiple vehicular units for raising it for transport. It is also known to interconnect air suspension components in heavier vehicles such as buses for the purpose of varying the manner in which the load is distributed among the axles. The present invention is essentially embodied in the realization that an air suspension system can be designed for a vehicle, especially a trailer vehicle, to facilitate its loading and unloading. DISCLOSURE OF THE INVENTION The invention accordingly provides a vehicle compri- sing: a vehicle body; a pair of grcund wheels for the body; and suspension means resiliently supporting the vehicle' body with respect to the ground wheels; characterised in that the suspension means is so dimensioned and positioned as to be actuable to alter the relative vertical positions of the ground wheels and vehicle body from a normal condition in which the vehicle is mobile to one in which, with a first extremity of the vehicle body supported in a raised position, the vehicle body is inclined from said first extremity to a lowered extremity closely adjacent or in contact with the ground. The respective extremities may comprise opposite ends of the vehicle. In an especially advantageous application o the invention, the vehicle is a trailer with forwardly diposed draft means, and the respective extremities comprise the forward and rearward ends of the trailer. The suspension means is advantageously a fluid sus¬ pension comprising a plurality of pivotally mounted arms supporting the ground wheels and respective inflatable/ deflatable flexible bags mounted between the vehicle body and the said arms. Each bag may be disposed so as to contract/extend on deflation/inflation in a horizontal direction in said normal condition of the vehicle, each bag being mounted t its respective said arm by being attached to lug or brack means extending fixedly from the arm. It may be desirable for said arms to be connected together in pairs by axles extending under the vehicle body and for .the ground wheels to be mounted in co-axial pairs, each wheel axis being disposed OM above but parallel to an associated said axle. BRIEF DESCRIPTION OF DRAWINGS The invention will be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a vertical cross-section through, a tandem trailer constructed in accordance with the invention, showing th.e ground wheels and suspensions at one side of the trailer when in its mobile con- dition; Figure 2 is a view similar to Figure 1 but showing the trailer in a loading/unloading condition; Figure 3 is an underneath view of one side of the trailer depicted in Figure 1; and Figure 4 is a view similar to Figure 1 of a second embodiment of trailer in accordance with the invention, shown in its mobile condition. BEST MODE OF CARRYING OUT THE INVENTION The tandem trailer 10 illustrated somewhat diagrammaticall .in Figures 1 to 3 ' includes a body 12 which essentially comprises a chassis 14 supporting a floor 16, side boards 18 and front board 19. There is no tailgate and the forward end of the chassis is secured to draw means consisting of the usual A-frame 22 fitted in turn with a conventional ball socket 24 for attaching the trailer behind a draw vehicle. Four ground wheels 26 are mojnted to respective stub-axles or wheel pins 28. The trailer body 12 is resiliently supported with, respect to the ground wheels by suspension means including four air suspensions 30, one for each ground wheel. In Figures 1 and 2, only the wheels and suspensions at one side of the trailer are visible. Each air.suspension 30 comprises a slightly curved trailing arm 32 pivoted forwardly of its associated OMPI wheel to a shackle 34 depending from chassis 14. The rear ends of trailing arms 32 -underlie and directly support respective front and back axles 35a, 35b. Each axle carries two of the ground wheels 26, their associated wheel pins 28 being fixed to respective plates 36 which project upwardly from the associated axle. Respective generally cylindrical flexible air bags 38 are pivoted at their axially opposite ends to chassis 12 on the one hand β8a) and to approximately the mid point of trailing arms 32 on the other (38b) . The axes of the air bags are thereby generally upright. The four air bags 38 may be inflated or deflated by camion air-supply system including conduits 40 connected to a single control valve/compressor assembly 42 which is not necessarily inboard as shown and is employed to inflate or deflate the air bags to alter the condition of the trailer between that shown in Figure 1, in which it is level and mobile along ground 8, and that shown in Figure 2. In. the latter condition, with the trailer in tow, the forward end of the trailer body remains supported at the ball and socket coupling in a raised position, typically between 300 and 600 mm above the ground, while the rear or tail end 25 is lowered into contact with, or nearly into contact with, ground 8. The trailer body and chassis are thus inclined tail to front and are located between the wheels, almost resting on the rear axle 35b. It will be now seen why it is advantageous to employ a "drop-axle" construction in which the ground wheels, especially the rear, are mounted in co-axial pairs with each wheel axis disposed above but parallel to the associated axle. It will be appreciated that the suspension means comprised of the air bags 38, the trailing arms 32 and the plates 36, are readily actuable, by operating a control valve in assembly 42, to deflate the bags to bring about the illustrated lowering of the trailer body relative to the ground wheels . Once bought to the inclined position in this simple manner, a load may be easily transferred between trailer and ground. For example, another vehicle is readily pushed up the gentle incline of the ' trailer directly from the ground or vice versa. In the case of a boat trailer, launch¬ ing or landing of the craft is facilitated by the inventive arrangement. The alternative construction shown in Figure 4, (in which like parts have like primed reference numerals) is especially suited to a case where clear¬ ance between the trailing arms and the underside of the chassis is. such, that it is difficult to provide an air bag of the required length in the mobile condition which can contract to the desired extent but does not distort or otherwise collapse when inflated. In this case the forward end of each trailing arm 32' is provi¬ ded with an upstanding lug 50 which is rigidly fixed to the trailing arm. A relatively shorter, generally cylindrical air bag 38' is mounted with its axis, and its direction of contraction/extension on deflation/ inflation, horizontal instead of upright, one end secured to lug 50 and the other to a chassis mount 54. By appropriate choice of displacement between the two mounting points on each pair of lugs 50, 54 as the bags inflate or deflate, the length of each, air bag may be c ipromised with respect to its required pressure to obtain the optimum arrangement effective to lower or raise the trailer to or from a position such as is shown in Figure 2. If desired, bags 38' may not be directly above arms 32'. By modification of lugs 50, the bags and arms may be respectively inboard and outboard of the chassis. In a further modification, arms 32, 32' may be rigid, straight beams or bars, rather than of curved plate construction. The arms may directly mount the ground wheels rath.er than the axles, which will nevertheless be preferably below the wheel axes. The axles may usefully be interconnected by means 5 such as sway bars to enhance the stability of the vehicle as it is travelling along the ground. It is to be understood that any vehicle construc¬ tion, especially trailer construction, in which the suspension system is designed to permit controlled 10. alteration of the vehicle condition between a generally horizontal mobile condition and an inclined condition to facilitate loading and unloading is within the concept of the invention. While an air suspension has been particularly described, any type of suspension 15 having characteristics which may be varied to obtain the result desired, would be satisfactory. OMP

Claims: CLAIMS:- 1. A vehicle comprising: a vehicle body; a pair of ground wheels for the body; and suspension means resiliently supporting the vehicle body with respect to the ground wheels; characterized in that the suspension means is so dimensioned and positioned as to be actuable to alter the relative vertical positions of the ground wheels and vehicle body from a normal condition in which the vehicle is mobile to one in which, with a first extremity of the vehicle body supported in a raised position, the vehicle body is inclined from said first extremity to a lowered extremit closely adjacent or in contact with the ground. 2. ' A vehicle according to claim 1 further charac¬ terized in that the respective extremities comprise opposite ends of the vehicle. 3. A vehicle according to claim 1 or 2 further characterized in that the vehicle is a trailer with forwardly disposed draft means, and in that said respective extremities comprise the forward and rearward ends of the trailer. 4. A vehicle according to claim 1, 2 or 3, further characterized in that the suspension means is a fluid suspension comprising a plurality of pivotally mounted arms supporting the ground wheels and respective inflatable/deflatable flexible bags mounted between the vehicle body and the said arms. 5. A vehicle according to claim 4 further charac¬ terized in that each bag is disposed so as to contract/ extend on deflation/inflation in a horizontal direction in said normal condition of the vehicle, each bag being mounted to its respective said arm by being attached to lug or bracket means extending fixedly from the arm. OMPI 6. A vehicle according to claim 5 further charac¬ terized in that said arms are connected together in pairs by axles extending under the vehicle body, and in that the ground wheels are mounted in co-axial pairs, each wheel axis being disposed above but parallel to an associated said axle. 7. A vehicle according to claim 6 further charac¬ terized in that there is one said arm for each ground wheel, each wheel being pivoted to a respective plate which projects upwardly from an axle or arm. 8. A vehicle according to claim 6 or 7 further characterized in that said axles are interconnected by means to enhance the stability of the vehicle as it is travelling along a ground. 9. A vehicle according to any one of claims 4 to 8 -further characterized by fluid supply conduits secured to the vehicle body and coupled to said bags to permit inflation and deflation of the bags. OMPI

Inventors: MCMINN A
Applicants: MCMINN A
Application year: 1981
Main classification: B60G17
IPC codes: B60G5, B60G11, B60G17, B60P1, B60P3