GB2171370A - Commercial vehicles - Google Patents

Abstract

A commercial vehicle comprises a chassis having a front section 6 and a rear section, both sections having non-steerable wheels. The front and rear sections are pivotally connected and drive means operable from the steering mechanism of the vehicle are provided for controlling the pivotal connection. The front and rear sections thus both pivot relative to one another and provide directional control of the vehicle when in motion. The front section carries the engine and transmission. The steering gear includes a two part slew ring, a pinion gear driving one of the parts (Fig 1). <IMAGE>

Description

SPECIFICATION Improvements in commercial vehicles This invention relates to improvements in commercial vehicles.

Commercial vehicles used by brewery companies for product deliveries to retail outlets have to meet a number of specialised requirements.

A truck load of full beer kegs is particularly heavy leading to problems in arranging the weight distribution of the load so as to ensure that the maximum permitted axle loadings for the vehicle are not exceeded. This problem can be overcome by using large articulated vehicles. However, there are certain difficulties in using such vehicles. In particular, such vehicles require drivers with a higher grade of licence thereby increasing labour costs and they are difficult to manoeuvre making deliveries to certain urban locations extremely difficult.

Thus previously, rigid trucks have been used with the problems of weight distribution and overloading of the front axle being overcome by, for example, erecting a bulkhead towards the front of the loading area of the truck to restrict the loading area and prevent it from being loaded up towards the front.

This is obviously inefficient as part of the loading area, which could be usefully employed when lighter goods are being carried, is inaccessible. Alternativeliy trucks having four steerable wheels have been used. However, such trucks are more expensive to purchase initially and in use have the problem of limited steering lock due to space limitations around the cab area of the vehicle chassis. Furthermore the increase in front axle loading capacity is only around half a ton.

A further problem is that as the driveshaft of the vehicle has to run beneath the loading area it is not possible to arrange the loading area at a low height for ease of loading and unloading. This can be overcome by running a tunnel, containing the driveshaft, down the centre of the loading area.

However the presence of a central driveshafttunnel on the loading area restricts the area available for load carrying and also makes it impractical to unload from one side only.

According to the present invention there is provided a vehicle comprising a chassis having a first section and a second section, both sections having non-steerable ground engaging wheel means, wherein the first section and second section are controllably pivotally connected and drive means are provided for controlling the pivotal connection so as to controllably pivot the first section relative to the second section and thereby provide directional control of the vehicle when in motion.

Preferably mechanical drive means are mounted on the first section of the chassis, said drive means in use driving the wheel means of said first section.

Preferably also the wheel means on said first section comprisefourwheels rotatable on a single axis.

Preferably also the pivotal connection between the first and second sections comprises a slew ring having an upper portion fixed to the second section of the chassis and a lower portion fixed to the first section of the chassis, the upper and lower parts being rotatably connected.

Preferably also there is provided drive means for rotating the upper and lower portions of the slew ring relative to one another comprising a drive pinion on one portion of the ring which cooperates with internal gear means on the other portion of the ring.

Most preferably movement of said drive pinion is controlled by a steering wheel of said vehicle.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view illustrating the steering mechanism of a vehicle made in accordance with the present invention; Figure 2 is a plan view of the first section of the chassis of a vehicle made in accordance with the present invention; Figure 3 is a side view of the section of the vehicle chassis of Figure 2; and Figure 4 is a side view of one embodiment of a vehicle made in accordance with the present invention.

Referring to the drawings, a vehicle 1 according to the invention has a front cab section 2 and a rear section 3, having a loading area 4. The cab section 2 is pivotally connected to a front chassis 6 at 5.

The front chassis 6 has mounted on it an engine 7, a gearbox 8, a transfer box 9 and an axle 10 having a differential unit 11. The axle 10 has two pairs of roadwheels 12 mounted on it.

The rear section 3 supports the cab section 2 and is connected by the pivotal connection 5 to the chassis 6 at one end and at the other end is supported by a number of roadwheels 14.

Steering for the vehicle 1 is provided by the pivotal connection 5 between the chassis 6 and the rear section 3.

This pivotal connection 5 is in the form of a slew ring 15 having an upper ring 16, which is mounted on the rear section 3 and a lower ring 17 rotatable relative to the upper ring 16, mounted on the chassis 6. The steering wheel 18 of the vehicle 1 is connected via a steering box 19, rotatable shafts 20 and 21 and a servo unit 22 to a bevel gear assembly 23 mounted on the upper ring 16. A cross-shaft 24 connects the bevel gear assembly 23 to a similar assembly 25 at the opposite side of the ring 16. Intermediate shafts 26 connect the bevel gear assemblies 23 and 25 to drive pinions 27 which intermesh with a gear 28 on the inner surface of the lower ring 17.

In use the vehicle 1 is driven in a normal manner with the engine 7 driving the front wheels 12 via the gearbox 8, transfer box 9 and the axle and differential unit 10 and 11. To steer the vehicle the steering wheel 18 is turned to the left orto the right as desired thus operating the drive pin ions 27 via the steering box 19, shafts 20 and 21, steering servo 22, the bevel gear assembly 23, cross-shaft 24, bevel gear assembly 25 and intermediate shafts 26. The drive pinions 27 co-operate with the gear 28 on the lower ring 17 thus rotating the upper 16 and lower 17 parts of the ring 15 relative to one another. This alters the angle between the chassis 6 and the rear section 3 of the vehicle 1 thus causing the vehicle to follow a curved path.

There are a number of advantages of this type of vehicle. As the front wheels are not required to be steerable it is possibie to have four wheels in a single axle thus increasing the load carrying capacity of the vehicle. The small turning circle available with this type of steering arrangement overcomes the problem of limited steering lockwhich previous trucks having twin front axles with four steerable wheels have had.

As all the running gear of the vehicle is contained within the chassis 6 there is no driveshaft running beneath the loading area 4 of the rear section 3. Thus the loading area 4 can be arranged at a low height, for example fifteen inches, for easy loading and unloading without a driveshafttunnel in the centre preventing access from both sides to the full width of the loading area.

As the pivotal movement between the front and rear sections of the vehicle is directly controlled by the steering mechanism the vehicle does not have the problems of reversing which a conventional articulated vehicle has.

Various other embodiments of vehicles can be constructed incorporating this type of steering mechanism.

Claims (7)

1. A vehicle comprising a chassis having a first section and a second section, both sections having non-steerable ground engaging wheel means, wherein the first section and second section are controllably pivotally connected to each other and drive means are provided for controlling the pivotal connection so as to pivot the first section relative to the second section and thereby provide directional control of the vehicle when in motion.

2. Avehicle as claimed in Claim 1 wherein mechanical drive means are mounted on the first section of the chassis, said drive means being operable to drive the wheel means of said first section.

3. A vehicle as claimed in Claim 1 or 2 wherein the wheel means on said first section comprise four wheels rotatable on a single axle.

4. A vehicle as claimed in any one of the preceding Claims wherein the pivotal connection between the first and second sections comprises a slew ring having an upper portion fixed to the second section of the chassis and a lower portion fixed to the first section of the chassis, the upper and lower portions being rotatably connected.

5. A vehicle as claimed in Claim 4 wherein there are provided drive means for rotating the upper and lower portions of the slew ring relative to one another said drive means comprising a drive pinion on one portion of the ring which cooperates with internal gear means on the other portion of the ring.

6. A vehicle as claimed in Claim 5 wherein movement of said drive pinion is controlled by a steering wheel of said vehicle.

7. Avehicle substantially as hereinbefore described with reference to the accompanying drawings.