GB1563875A

GB1563875A - Anti-jacknife arrangements in articulated road vehicles

Info

Publication number: GB1563875A
Application number: GB1870177A
Authority: GB
Original assignee: Ward D F
Current assignee: Ward D F
Priority date: 1975-01-03
Filing date: 1977-05-04
Publication date: 1980-04-02

Description

(54) ANTI-JACKNIFE ARRANGEMENTS IN ARTICULATED ROAD VEHICLES (71) I, DAVID FREDERICK WARD, a British subject of 9 Honeypot Lane, Brentwood, CM14 4QT, Essex, England, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement :- This application is for a patent of addition to my application 192/75 (serial no.

1, 475,822), and relates to anti-jacknife arrangements embodied in articulated road vehicles.

In the parent application I describe and claim an articulated road vehicle comprising a tractor and a semi-trailer releasably coupled to one another by a fifth wheel coupling, the centre of gravity of the tractor being located at or rearward of the king pin axis of the fifth wheel coupling.

I have now found that the anti-jacknife effect obtained by using the invention described and claimed in the parent application is still retained if the centre of gravity of the tractor is located forward of the king pin axis, provided that the centre of gravity lies behind the mid-point of the wheel base of the tractor.

Thus in accordance with the present invention, there is provided an articulated road vehicle comprising a tractor and a semi-trailer releasably coupled to one another by a pivotal coupling allowing articulation about a substantially vertical pivot axis, the centre of gravity of the tractor lying forward of the vertical pivot axis but behind the mid-point of the wheel base of the tractor. Preferably the centre of gravity lies at a distance behind the mid-point of the wheel base which is at least equal to 15% of the length of the wheel base.

For a two axle vehicle the wheel base is defiined as the distance between the two axles as viewed from the side of the vehicle.

Preferably, the centre of gravity lies forward of the pivot axis by an amount which does not exceed a quarter of the length of the wheel base of the tractor. A typical wheel base for the tractor of an articulated lorry would be 10 ft. so that, in this case, the centre of gravity of the tractor should lie not more than 2.5 ft. forward of the pivot axis of the coupling between the tractor and the semi frailer. On present articulated lorries, the centre of gravity of the tractor typically lies about 5 ft. forward of the pivot axis due to the mounting of the engine at the front of the tractor.

For a lorry in which the tractor includes three axles, the wheel base is defined as the distance between the front axle and the mid- point of the two rearmost axles, and for a a tractor having four axles the wheel base is defined as the distance between the mid-point between the two foremost axles and the mid point between the two rearmost axles.

The required location of the centre of gravity of the tractor is preferably achieved by mounting the tractor engine and/or other heavy ancillary components, such as the gearbox, behind the mid-point of the wheel base. By positioning the centre of gravity behind the mid-point of the wheel base, lateral forces exerted by the semi-trailer through the king pin of a fifth wheel coupling in a poten tial jacknifing situation are unlikely to pivot the tractor about any axis. On the contrary, the weight of the tractor acting behind the mid-point of the wheel base tends to oppose any such pivoting movement.

A vehicle embodying the invention may be substantially as illustrated in the parent appli cation, the only difference being that the centre of gravity of the tractor is located more forwardly provided it remains behind the mid-point of its wheel base.

WHAT I CLAIM IS : 1. An articulated road vehicle comprisnig a tractor and semi-trailer releasably coupled to one another by a pivotable coupling allowing articulation about a substantially vertical pivot axis, the centre of gravity of the tractor lying forward of the vertical pivot axis but behind the mid-point of the wheel base of the tractor.

2. A vehicle according to claim 1 in which the centre of gravity of the tractor lies at a distance behind the mid-point of its wheel base which is at least equal to 15% ouf the length of its wheel base.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. (54) ANTI-JACKNIFE ARRANGEMENTS IN ARTICULATED ROAD VEHICLES (71) I, DAVID FREDERICK WARD, a British subject of 9 Honeypot Lane, Brentwood, CM14 4QT, Essex, England, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement :- This application is for a patent of addition to my application 192/75 (serial no. 1, 475,822), and relates to anti-jacknife arrangements embodied in articulated road vehicles. In the parent application I describe and claim an articulated road vehicle comprising a tractor and a semi-trailer releasably coupled to one another by a fifth wheel coupling, the centre of gravity of the tractor being located at or rearward of the king pin axis of the fifth wheel coupling. I have now found that the anti-jacknife effect obtained by using the invention described and claimed in the parent application is still retained if the centre of gravity of the tractor is located forward of the king pin axis, provided that the centre of gravity lies behind the mid-point of the wheel base of the tractor. Thus in accordance with the present invention, there is provided an articulated road vehicle comprising a tractor and a semi-trailer releasably coupled to one another by a pivotal coupling allowing articulation about a substantially vertical pivot axis, the centre of gravity of the tractor lying forward of the vertical pivot axis but behind the mid-point of the wheel base of the tractor. Preferably the centre of gravity lies at a distance behind the mid-point of the wheel base which is at least equal to 15% of the length of the wheel base. For a two axle vehicle the wheel base is defiined as the distance between the two axles as viewed from the side of the vehicle. Preferably, the centre of gravity lies forward of the pivot axis by an amount which does not exceed a quarter of the length of the wheel base of the tractor. A typical wheel base for the tractor of an articulated lorry would be 10 ft. so that, in this case, the centre of gravity of the tractor should lie not more than 2.5 ft. forward of the pivot axis of the coupling between the tractor and the semi frailer. On present articulated lorries, the centre of gravity of the tractor typically lies about 5 ft. forward of the pivot axis due to the mounting of the engine at the front of the tractor. For a lorry in which the tractor includes three axles, the wheel base is defined as the distance between the front axle and the mid- point of the two rearmost axles, and for a a tractor having four axles the wheel base is defined as the distance between the mid-point between the two foremost axles and the mid point between the two rearmost axles. The required location of the centre of gravity of the tractor is preferably achieved by mounting the tractor engine and/or other heavy ancillary components, such as the gearbox, behind the mid-point of the wheel base. By positioning the centre of gravity behind the mid-point of the wheel base, lateral forces exerted by the semi-trailer through the king pin of a fifth wheel coupling in a poten tial jacknifing situation are unlikely to pivot the tractor about any axis. On the contrary, the weight of the tractor acting behind the mid-point of the wheel base tends to oppose any such pivoting movement. A vehicle embodying the invention may be substantially as illustrated in the parent appli cation, the only difference being that the centre of gravity of the tractor is located more forwardly provided it remains behind the mid-point of its wheel base. WHAT I CLAIM IS :

1. An articulated road vehicle comprisnig a tractor and semi-trailer releasably coupled to one another by a pivotable coupling allowing articulation about a substantially vertical pivot axis, the centre of gravity of the tractor lying forward of the vertical pivot axis but behind the mid-point of the wheel base of the tractor.

3. A vehicle according to claim 2 in which the distance between the centre of gravity and the pivot axis does not exceed a quarter of the length of the wheel base of the tractor.

4. A vehicle according to claim 2 or claim 3 in which the centre of gravity lies not more than 2.5 feet forward of the pivot axis.