GB2276128A - Goods vehicles with separable cab and load space sections. - Google Patents

Abstract

Front section 10 includes a chassis-part 15 on which are mounted a pair of power-driven steerable road wheels 13 and a drivers cab 12. Rear section 11 defines a load-carrying space and has a pair of road wheels 14, the rear section being constructed as a chassis-less body on which are directly mounted suspension elements for the road wheels. The front of the rear section has a pair of mounting plates 24 appropriately positioned, so that the rear section 11 may be bolted to a similar pair of mounting plates 16 attached to the chassis part 15 of the front section 10. The rear suspension may be mounted to a space frame, or directly to a stressed skin where this construction is used. <IMAGE>

Description

GOODS VEHICLES This invention relates to goods vehicles.

Most modern passenger cars and certain light vans are constructed on the monocoque (or stressed-skin) principle. In this, no separate chassis is provided, but instead the vehicle body is designed and constructed to permit the attachment of key components direct to the vehicle body itself. Thus, the body is designed to have sufficient strength to permit the direct mounting thereto of the suspension, the engine, the transmission and so on. By contrast, most goods vehicles are constructed using a separate chassis which supports the suspension for the road wheels, the engine and transmission, and so on. This construction has the advantage of considerably greater flexibility, for any one of a wide variety of designs of body may be mounted on the chassis, depending upon the intended use of the vehicle. Moreover, it is easier to manufacture a highstrength chassis if no great account has to be taken of the body style to be mounted thereon.

A disadvantage of a constructional technique using a separate chassis is that the cost of the finished vehicle as well as its weight tend to be significantly higher than if a monocoque construction is employed, for a given vehicle type or body style. Also, and particularly in the case of a box truck or van, the body has to be mounted above the chassis, and so usually above the road wheels. This restricts the total available volume for a given vehicle length, and also raises the centre of gravity for a given load, which may reduce stability during certain operating conditions.

In an attempt to increase the flexibility of vehicle construction whilst using a chassis design, it is known to provide a vehicle chassis which is manufactured in two parts joined together: a front part carrying the engine, transmission and driven steerable wheels, and a rear part carrying at least one pair of road wheels and being adapted to support a vehicle body. In this way, a vehicle chassis of an appropriate length may be provided for a particular body style, by attaching to the front chassis part a rear chassis part of a suitable length. By having road wheels on the rear chassis part as simple undriven wheels, relatively few further connections have to be made between the two chassis parts once the two parts have been joined together, these connections being primarily for the electrical systems and the hydraulic braking system.

Though the constructional technique described above may offer a greater flexibility to a vehicle manufacturer at a reduced cost, nevertheless there is still the penalty of an increased overall weight of a chassis construction. Also, the vehicle body still has to be mounted above the chassis, with the attendant disadvantages thereof. It is a principal aim of the present invention to address these problems.

According to one aspect of the present invention, there is provided a goods vehicle comprising a front section including a chassis-part on which are mounted a pair of power-driven steerable road-wheels and a driver's cab, and a rear section including at least one pair of road wheels and defining a load-carrying space, the rear section being constructed as a chassis-less body on which are directly mounted suspension elements for said road wheels, the front of the rear section having a pair of mounting plates by means of which the rear section is bolted to a corresponding pair of mounting plates attached to the chassis-part of the front section.

It will be appreciated that by employing the constructional technique of this invention, a goods vehicle having a load-carrying body is furnished without the need to employ a chassis or chassis-part for the load-carrying body itself. This leads to a reduction in the overall weight of the vehicle, so permitting a greater load to be carried for a given set of vehicle parameters, and also allows for the possibility of lowering the centre of gravity of the body. On the other hand, the advantages of using a chassis-type construction for the front section of the vehicle are still maintained, such as the flexibility this offers in allowing one design of front section to be used with a wide variety of different bodies.

The load-carrying space of the rear section is preferably in the form of a closed container, so that the completed vehicle is of the kind known as a box truck or van. However, it would be possible to construct other kinds of chassis-less load-carrying sections for attachment to the front section.

Particularly in the case of a box vehicle, it is preferred for the rear section to be constructed as a clad space-frame utilising a plurality of members of relatively small cross-sectional dimensions and interconnected to define a frame on which appropriate cladding is mounted. Such a space-frame may include the mounting plates for bolting to the chassis part of the front section, and also appropriate mounting points for the rear suspension. Another possibility would be to construct the rear section as a true monocoque, where the body shell is stressed directly to carry the suspension and mounting plates for the front section.

Advantageously, each road wheel of the rear section is carried by a leading or trailing link suspension assembly having a relatively small extent across the width of the vehicle body. In this way, it is possible to profile the body to accommodate the wheels and appropriate suspension components within a recess on each side of the body, so enabling the loadcarrying space to have a floor which is below the upper surface of the road wheels, even when the suspension is not compressed. Preferably, the floor of that loadcarrying space is as low as substantially the centre of the road wheels, when the suspension is at least partially compressed.

By way of example only, one specific embodiment of a goods vehicle constructed and arranged in accordance with the present invention will now be described in detail, reference being made to the accompanying drawings in which: Figure 1 is a side view of the embodiment of goods vehicle; Figure 2 is a transverse diagrammatic crosssectional view through the vehicle; Figure 3 is an exploded perspective diagram showing the junction between the front and rear sections; Figure 4 is a side view of the front region of the rear section, with the cladding cut away for clarity; Figure 5 is a side view of the wheeled region of the rear section, with parts cut away for clarity; and Figure 6 is a plan view of the suspension region of the rear section, again with parts cut away for clarity.

Referring to the drawings, there is shown an embodiment of goods vehicle of this invention and having a front section 10 conjoined to a rear section 11. The front section includes a driver's cab 12 and steerable front wheels 13 for the vehicle, as well as an internal combustion engine and a transmission arrangement drivingly coupled to the steerable front wheels 13. The rear section 11 is in the form of a load-carrying body of an enclosed box design, typically having rear-access doors (not shown). Alternatively, a roller shutter could be provided to gain access to the interior of the rear section; such a shutter or other access doors could be provided on a side wall of the rear section, if preferred. The rear section includes two pairs of road wheels 14.

The front section 10 includes a chassis having a pair of parallel side rails 15 on which the cab 12 is mounted, along with the front wheels 13, the engine and transmission, and so on. Each chassis rail 14 terminates behind the cab in a mounting plate 16 provided with through-holes 17.

The rear section 11 is constructed in the form of a chassis-less space-frame from a plurality of members each of relatively small cross-sectional dimensions and attached together to form a strong and rigid structure enclosing the load-carrying volume. Typically, the space-frame members are of hollow box-section steel, welded together at their ends as appropriate in order to form a braced lattice structure.

Figure 3 shows the front part of the space-frame structure and, as can be seen, this consists of principal members 18 extending both horizontally and vertically, and subsidiary bracing members 19 which extend at acute angles between the principal members 18, in order to impart rigidity and high strength to the overall structure. Typically, the principal members 18 are of 50 x 25 mm hollow box section steel, and the subsidiary bracing members 19 are of 20 x 20 mm hollow box section steel. Extending transversely across the front of the rear section, there are two principal members 20 and 21 which are attached at their respective ends to vertical corner members 22 and to two intermediate vertical members 23, as appropriate.

Spaced inwardly from the corner members 22 and attached to the principal and intermediate members 20, 21 and 23 are two mounting plates 24 each having through-holes 25; the configuration of those mounting plates 24 and their relative disposition is such that those plates 24 may be bolted to the mounting plates 16 provided on the front section chassis rails 15.

The load-carrying floor of the rear section 11 is also constructed in the same way as has been described above, using principal members crossed-braced by diagonally-extending subsidiary members. However, in the region of the two pairs of road wheels 14, further transverse principal members 26 are arranged to provide mounting points for independent rear wheel suspension units 27. Each of these units 27 is wholly selfcontained and independent of the others, to allow the respective road wheel 14 supported thereby to move generally vertically as required to absorb unevenness in a road surface over which the vehicle is travelling.

Typically, each of these units may include a leading or trailing arm pivoted at one end and mounting a hub for the road wheel at its other, free end. The arm is supported by a mass of elastomeric material which may be compressed to provide a resilient suspension for the road wheel.

The hub (not shown) for the road wheel includes a hydraulic braking assembly (also not shown); all of those braking assemblies are hydraulically linked to the braking system of the front section 10 by means of appropriate hydraulic pipes (not shown).

The rear section space-frame structure is clad in light-weight aluminium sheeting 29, secured to the outside of the structure members by, for example, socalled "POP" rivets, or by other suitable fastenings known in the art. Such cladding does not contribute significantly to the overall strength of the structure.

In the region of the rear section road wheels 14, both the space-frame structure and the cladding are profiled to define a generally box shaped recess 30 (Figures 5 and 6) in which the road wheels are accommodated and allowed to perform their full permissible suspension travel. However, since the suspension units 27 are mounted beneath the principal members 26, the width of that box shaped recess 30 need be only slightly greater than the width of the road wheels themselves. As such, the recess does not intrude greatly into the load-carrying space of the vehicle body.

As will be appreciated from the foregoing, the constructional technique described above for a goods vehicle allows the manufacture of a complete vehicle specifically intended for a particular purpose, but in an economical manner. The body may have a relatively large volume for a given overall height of vehicle and moreover the centre of gravity of that body may be relatively low. The body may be manufactured wholly separately, and typically by a different manufacturer, from the front section and of course a wide range of different body designs may be secured to a single design of front section.

Claims (9)

1. A goods vehicle comprising a front section including a chassis-part on which are mounted a pair of power-driven steerable road-wheels and a driver's cab, and a rear section including at least one pair of road wheels and defining a load-carrying space, the rear section being constructed as a chassis-less body on which are directly mounted suspension elements for said road wheels, the front of the rear section having a pair of mounting plates by means of which the rear section is bolted to a corresponding pair of mounting plates attached to the chassis-part of the front section.

2. A goods vehicle as claimed in claim 1, wherein the load-carrying space of the rear section is in the form of a closed container.

3. A goods vehicle as claimed in claim 2, wherein the rear section is constructed as a clad space-frame utilising a plurality of members of relatively small cross-sectional dimensions and interconnected to define a frame on which appropriate cladding is mounted.

4. A goods vehicle as claimed in claim 3, wherein the space frame includes said mounting plates for bolting to the chassis part of the front section, and also appropriate mounting points for the rear suspension.

5. A goods vehicle as claimed in claim 2, wherein the rear section is a monocoque construction using a stressed skin body shell which directly carries the suspension and mounting plates for the front section.

6. A goods vehicle as claimed in any of the preceding claims, wherein each road wheel of the rear section is carried by a leading or trailing link suspension assembly.

7. A goods vehicle as claimed in claim 6, wherein the body is profiled to accommodate the wheels and appropriate suspension components within a recess on each side of the body, the load-carrying space having a floor which is below the upper surface of the road wheels.

8. A goods vehicle as claimed in claim 7, wherein the floor of the load-carrying space is substantially on the level of the centre of the road wheels, when the suspension is at least partially compressed.

9. A goods vehicle as claimed in claim 1 and substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.