GB2081188A

GB2081188A - Vehicle with Tiltable Load Platform

Info

Publication number: GB2081188A
Application number: GB8024899A
Authority: GB
Original assignee: George Neville Truck Equipment Ltd
Current assignee: George Neville Truck Equipment Ltd
Priority date: 1980-07-30
Filing date: 1980-07-30
Publication date: 1982-02-17

Abstract

The vehicle is a trailer having a chassis (20) on which is tiltably mounted a body (22) raisable by a ram (40). A rear axle (30a) of the trailer is movable rearwardly of the chassis from a towing position to a tilting position (at 30a) so that, in the tilting position, the axle is rearward of the centre of gravity (25) of the tilted body. A sub-frame (28) carries the rear axle and is pivoted (at 29) to the chassis. A ram (33) acts on a linkage (50) between the chassis and the sub- frame to tilt them relative to each other to effect raising of the body. <IMAGE>

Description

SPECIFICATION Vehicle with Tiltable Load Platform This invention relates to a vehicle with a rearwardly tiltable load platform. Such vehicles are well known, e.g. in the form of a trailer having a chassis and a load platform rearwardly tiltable relative to the chassis to permit tipping. The load platform may form the bottom of a container.

It is advantageous, for stability of the vehicles, for the support wheels for the load platform to be close to the centre of gravity of the load, but spaced rearwardly from the centre of gravity. The stability reduces, if the wheels are positioned further to the rear, especially in a trailer, since this increases the load on the towing hitch.

As a load platform is rearwardly tilted for tipping purposes, the centre of gravity of the platform and its load moves rearwardly relative to the chassis and relative to the support wheels. If the wheels are positioned to give good balance when towing (i.e. near to the centre of gravity in the untilted state of the load platform) then the centre of gravity moves during tipping to a position to the rear of the wheels. This tends to lift the forward end of the vehicle and, in the case of a trailer can cause vertical "jackknifing". This effect is worstened by the load as it moves rearwardly on the platform during a tipping operation. If the wheels are positioned to prevent this effect, then the vehicle becomes unbalanced for towing and a compromise is, therefore, usually necessary.

Some vehicles, especially trailers, are provided with lifting means for raising the tiltable load platform relative to the chassis. This can be advantageous where it is desired to tip into a high receptacle. Scissor-type linkages are often provided for this purpose. If the platform is raised vertically, so that both the centre of gravity of the load and platform, and the axis of tilt also move vertically, then the moment about the support wheels during tipping will be even greater in the raised position. It is possible to design the scissor linkage, so that, on raising of the platform, a subframe carrying the platform is moved forwardly of the vehicle.This reduces the problem to some extent, but the movement is limited by the linkage and also by the fact that the rear of the platform cannot be far forward of the rear of the chassis, since the latter must be backed up to the receptacle into which the load is to be tipped.

In accordance with one aspect of this invention, a vehicle has a chassis provided with a rearwardly tiltable load platform arranged so that the centre of gravity of the platform is forward of the rear axle of the vehicle in the non-tilted state, the rear axle being slidably movable relative to the chassis to a more rearward location to reduce or prevent movement of the centre of gravity rearwardly of the rear axle as the platform moves to its tilted position.

The invention may reside in a tipping vehicle having a chassis provided with a rear axle, means slidably mounting the axle for movement along the trailer from a relatively forward position to a relatively rearward position, a load platform, means mounting the platform on the chassis and for raising the platform relative to the rear axle, and means for rearwardly tilting the platform.

Reference is now made to the accompanying drawings, wherein: Figure 1 is a diagrammatic side elevation of a trailer, according to the invention; and Figure 2 is a similar view of the same trailer with a load platform thereof in a raised and tilted position.

Referring to Figure 1, the trailer shown comprises a chassis 20 fitted with a towbar 24 at its forward end. A sub-frame 28 is mounted on the chassis 20 for relative pivotal movement about a transverse, horizontal axis 29. A container 22 having a load platform 22a is carried by the chassis 20 and pivoted thereto about a transverse axis 23 at the rear of the trailer.

A rear axle 30a carries wheels 30 and is carried by the sub-frame 28. The axle is mounted for sliding movement longitudinally of the trailer.

The normal position of the axle, for towing of the trailer is shown by the letter T. In this position, the wheels 30 are just to the rear of the centre of gravity 25 of the loaded platform. The axle 30a and one of the wheels 30 are shown in Figure 1 in a position moved to the rear of the trailer, this being the position for greater stability during a tipping operation i.e. during rearward tilting of the load platform 22a. The platform can be tilted about the axis 23 by means of a hydraulic ram 40 pivoted at 41 to the chassis and at 42 to the platform. As can be seen from Figure 1, during tiltinlw, the centre of gravity 25 moves to a position R, which is forward of the axle 30a, but rearward of the normal axle position at T.

The axle can be fixed in either of the two indicated positions by means not shown and the movement of the axle may be effected simply by releasing the appropriate fixing means, applying brakes to the wheels 30 and moving the chassis.

The fixing means may be, for example, springloaded pegs engageable in selected holes.

Provision is also made for raising of the platform 22a and the platform can be tilted in the raised position. The titled and raised position is shown in Figure 2. The chassis 20 itself can be upwardly pivoted about the axis 29 relative to the sub-frame 28. The sub-frame 28 also tilts slightly about the axis of the wheels 30. This movement raises the platform 22a relative to the axle 30a and some forward movement of the rear axle occurs (i.e. from the position shown in dash lines to the position shown in full lines in Figure 2). The centre of gravity 25 moves to position H as the platform 22a is raised, this position being well forward of the axle 30a. Tilting is again effected by the hydaulic ram 40 and the centre of gravity 25 moves from position H to position J, which is still forward of the axle 30a.

For stability, interconnected linkages 50 is provided between the chassis 20 and the subframe 28 at each side of the trailer. Each linkage comprises a first link 31 and a second link 32 in a toggle arrangement. A hydraulic ram 33 is mounted between the sub-frame 28 and a pivot axis 35 on the first link 31. This axis 35 is spaced from the pivot point 36 between the two links.

The ram may be pivotally mounted on the subframe about the same axis 34 as the pivotal mounting of the linkage 50 on the sub-frame. The pivotal connection between the linkage 50 and the chassis 20 may be on the same axis as the pivotal mounting 23 of the platform 22a on the chassis.

Referring back to Figure 1, an alternative to the hydraulic ram 40 is shown in dash lines. This is a conventional "front end" arrangement comprising a ram 43 pivoted at 44 to the chassis 20. A collar 45 on the cylinder of the ram is pivoted to lugs on the container 22.

Claims

1. A vehicle having a chassis provided with a rearwardly tiltable load-carrying member, arranged so that the centre of gravity of the load carrying member is forward of the rear axle of the vehicle in the non-tilted state, wherein the rear axle is movable relative to the chassis to a more, rearward location to reduce or prevent movement of the centre of gravity rearwardly of the rear axle as the load-carrying member moves to its tilted position.

2. A vehicle according to Claim 1, including a sub-frame pivotally connected to the chassis and carrying the rear axle, and means to effect relative pivotal movement of the sub-frame and the chassis so as to raise the load-carrying member.

3. A vehicle according to Claim 2, comprising a linkage between the sub-frame and the chassis and a piston-cylinder unit acting on the linkage to effect said pivotal movement.

4. A vehicle according to Claim 3, wherein the linkage is a toggle linkage.

5. A vehicle constructed substantially as herein described with reference to the accompanying drawings.