GB2356607A

GB2356607A - Semi-trailer assembly

Info

Publication number: GB2356607A
Application number: GB0024758A
Authority: GB
Inventors: John Neenan Deeming
Original assignee: SDC TRAILERS Ltd
Current assignee: SDC TRAILERS Ltd
Priority date: 1999-11-29
Filing date: 2000-10-10
Publication date: 2001-05-30
Anticipated expiration: 2020-10-10
Also published as: GB0024758D0; GB2356608B; GB2356608A; GB0028779D0; IE20000970A1; GB2356607B

Description

2356607 1 I SEMI-TRAILER ASSEMBLY 2 3 This invention relates to a

semi-trailer assembly 4 which is adapted to be towed by a prime mover.

6 In the case of extending skeletal trailers, the 7 trailer can be extended and retracted in the 8 longitudinal direction of the trailer in order to 9 accommodate a range of standard containers.

11 One problem with extending skeletal trailers is that 12 under certain circumstances, e.g. during loading or 13 unloading, the centre of gravity of the load can be 14 to the rear of the centre of support of the wheels of the trailer, with the result that the trailer tends 16 to lift the rear of the prime mover. This can, for 17 example, render the prime mover difficult to start or 18 render it difficult for the trailer to be extended or 19 retracted.

2 1 It is conventional for such trailers to incorporate 2 three pairs of wheels. Previously, it has been 3 common practice to overcome the problems referred to 4 above by providing means for lifting the forward pair 5 of wheels of such trailers clear of the ground, with 6 the result that the trailer is supported by the 7 remaining two pairs of wheels. The effect of raising 8 the forward pair of wheels is to move the centre of 9 support for the trailer rearwardly, hence increasing 10 the load on the -orime mover. 11 12 This is currently achieved by a manual pneumatic 13 push/pull valve to raise the front axle. 14 15 However, one disadvantage of raising the forward pair 16 of wheels of a standard extending trailer unit clear 17 of the ground is that the vehicle combination of 18 trailer and drawing unit may not then conform to 19 present legal requirements for turning circle in this 20 configuration. It would then be illegal- to drive an 21 extended trailer on a public highway without the 22 forward pair of wheels in use. This situation can 23 easily occur if the user had forgotten to lower these 24 wheels after loading or unloading. 25 26 It is an object of the present invention to provide 27 an arrangement to maintain the legal requirements of 28 axle loading and turning circle requirements when the 29 trailer is extended. 30 3 1 According to one aspect of the present invention, 2 there is provided a semi-trailer assembly comprising 3 a trailer chassis extendable between contracted and 4 extended positions, and two or more sets of wheels 5 supporting the chassis, wherein the assembly includes 6 means for automatically controlling the lowering 7 and/or raising at least one of the pairs of wheels, 8 upon retraction and/or extension of the length of the 9 trailer chassis. 10 11 Preferably, the automatic means also disables and/or 12 overrides any manual lift-axle system on the semi13 trailer assembly. More preferably, the automatic 14 means is adapted to automatically lower any raised 15 pair of wheels upon extension of the trailer beyond a 16 pre-determined length. 17 18 The multi-wheeled trailer may involve two, three, 19 four or more sets, generally 'pairs' of wheels. 20 Preferably, the trailer is a semi-trailer assembly 21 comprising a trailer chassis and three pairs of 22 wheels arranged as a forward pair and two rearward 23 pairs for supporting the chassis and any load 24 thereon. 25 26 In one embodiment of the present invention there are 27 means for raising and/or lowering one pair, 28 preferably the forward pair, of wheels. More 29 preferably the means comprises a roller valve means 30 or similar electronic means adapted to lower the 31 forward pair of wheels upon extension of the trailer 4 1 chassis length beyond a pre-determined, e.g. legally 2 set, distance. This eliminates the possibility of 3 the vehicle being moved with the front axle raised if 4 the trailer is over a certain length. 5 6 Locking pins or other catches are provided for 7 locking the moveable portions of the chassis in one 8 of a number of alternative positions. 9 10 The controlling means could act on fluid pressure 11 means generally used to lower and/or- raise the pair 12 of wheels, which means could be separate or integral 13 with the main pressurised fluid syst-em. of the trailer 14 assembly. 15 16 Preferably, the means for lowering and/or raising the 17 relevant pair of wheels from the ground actuates a 18 separate container for pressurised air attached to 19 the axle beam, and is activated either by manual 20 operation or electrical valve. Such a valve could be 21 actuated to cause air flow to a pair of suspension 22 bags to be cut off and to exhaust to atmosphere, and 23 to divert air to the axle lifting bag (s), as the 24 trailer retracts in a longitudinal direction, leaving 25 the other pair(s) of wheels to support the load. 26 27 The means may be any suitable switch or trigger, 28 being either electronic, mechanical, magnetic or 29 optical, or a combination of one or more of these. 30 The means may be separate or integral with any 31 pressured fluid system on the chassis.

2 A valve system could also be provided for supplying 3 pressurised air to the pressurised fluid system of 4 the present invention for axle raising and/or 5 lowering. 6 7 The valve means for the present invention could 8 comprise one or more valves such as a pilot valve, 9 especially a 3/2 pilot valve, a push-pull valve, a 10 roller valve, an electrical solenoid valve, or an 11 electrical in-pulse valve. 12 Preferably, pressurised air is allowed to flow to 13 valve means such as a solenoid valve and a pull 14 valve. The pull valve can then be operated to divert is the air to valves which isolate the front air bags 16 and allows them to deflate without affecting any 17 other air bags. 18 19 According to a second aspect of the present 20 invention, there is provided a kit for application to 21 an extendable trailer chassis of a semi-trailer 22 assembly comprising means for automatically 23 controlling the lowering and/or raising of at least 24 one, e.g. the forward, pair of wheels supporting the 25 chassis, upon retraction and/or extension of the 26 trailer chassis. 27 28 The particular embodiments and features described 29 hereinbefore for the control means apply equally to 30 means for the kit. The kit should be useable with 31 any existing trailer chassis.

6 2 For a better understanding of the present invention 3 and to show more clearly how it may be carried into 4 effect reference will now be made, Joy the way of 5 example, to the accompanying diagrammatic drawing in 6 which: 7 8 Figure 1 shows one embodiment of a semi-trailer 9 assembly according to the present invention. 10 11 Semi-trailer assemblies of the extendible skeletal 12 type are well known in themselves and will not be 13 described in detail herein. 14 is Such trailer assemblies all include a trailer chassis 16 for supporting a load in the form of one or more 17 conventional containers and (generally) three pairs 18 of wheels (17a,b,c) disposed towards the rear of the 19 trailer for supporting the chassis and any load. The 20 wheels are provided with braking m&:,-hanisms, 21 conventionally operated by compressed air, and with 22 suspension systems, again conventionally 23 incorporating containers for pressurised. air. 24 25 Figure 1 is a diagrammatic illustration of a three 26 axle semi-trailer incorporating a fo.rward axle (1) 27 supported by forward air bags (3), a mid axle (5) 28 supported by mid air bags (7) and a rear axle (9) 29 supported by rear air bags (11) 30 31 Pressurised air is supplied to brakes (not shown) for 7 1 the wheels (17a,b,c) by way of conventional couplings 2 (not shown) and also to the air bags (3, 7, 11) to 3 maintain the air pressure therein. When the source 4 of pressurised air is turned off the drop in pressure 5 causes the brakes to be applied, but the air bags 6 (3,7,11) generally remain inflated. 7 8 Transverse locking pins (not shown) are provided to 9 lock the two portions of the chassis in one of a 10 number of alternative positions in order to adapt the 11 trailer for a particular container configuration to 12 be carried. 13 14 Previously, it has been conventional practice to 15 provide operating means, such as a push button, on 16 the side of the chassis for lifting and lowering 17 forward wheels. However, as discussed hereinbefore, 18 this does not comply with current legal requirements. 19 20 The pressurised air system again provides pressurised 21 air to the pressurised air containers on each axle 22 (3, 7, 11). These containers are interconnected 23 together, and a 3/2 pilot valve (15) is fitted 24 between the front containers (3) and the others (7, 2S 11) as illustrated. To lift the axle (1) and front 26 wheels (17a), the push button valve (13) is operated. 27 This allows pressurised air to flow to the 3/2 pilot 28 valve (15). The pilot slides to isolate the air bags 29 (7 and 11) of the rearward two pairs of wheels (which 30 remain pressurised) and to allow the forward pair of 31 air bags (3) to vent to atmosphere. It also allows a 8 1 lift axle system to pressurise two further air 2 containers (26) and so lift the forward pair of 3 wheels (17a). The locking pins can then be 4 disengaged to allow for the extension or retraction 5 of the trailer chassis. 6 7 The front axle (1) will then be lowered automatically 8 as the trailer extends beyond the legal 'Length 9 requirements for such a vehicle. This automatic 10 lowering is achieved by a roller valve (18). As the 11 trailer extends, the roller valve (28) comes into 12 contact with part of the chassis frame. This cuts 13 off the pressurised air supply to the 3/2 valves 14 (15), allowing the pilot to return to its original 15 position. This reconnects the front axle pressurised 16 air containers (3) to the rearward two axle air 17 containers (7, 11), and causes the lift-axle 18 pressurised air containers (26) to exhaust to 19 atmosphere. This ensures that as soon as the trailer 20 reaches the legal length requirements for a turning 21 circle, all three axles and tyres are on the ground. 22 23 The invention is not limited to the embodiments 24 herein described which may be varied in construction 25 and detail.

9

Claims

1 CLAIMS

2 3 1 A semi-trailer assembly comprising a trailer 4 chassis extendable between contracted and extended positions, and two or more sets of 6 wheels supporting the chassis, wherein the 7 assembly includes means for automatically 8 controlling the lowering and/or raising at least 9 one of the pairs of wheels, upon retraction and/or extension of the length of the trailer 11 chassis.

12 13 14

2. A semi-trailer assembly as claimed in Claim 1 which includes a manual lift-axle system, 16 wherein the automatic means disables and/or 17 overrides the manual lift-axle system.

18 19

3. A semi-trailer assembly as claimed in Claim 1 or 21 Claim 2 wherein the means is adapted to 22 automatically lower any raised pair or pairs of 23 wheels upon extension of the length of the 24 trailer chassis beyond a predetermined length.

26 27

4. A semi-trailer assembly as claimed in Claim 3 28 wherein the means controls the most forward pair 29 of wheels.

31 1 S. A semi-trailer assembly as claimed in any one of 2 Claims 1-4 having two, three cr four pairs of 3 wheels.

4 6. A semi-trailer assembly as claimed in Claim 5 6 wherein the trailer has three pairs of wheels.

7 8 7. A semi-trailer assembly as clad-med in any one of 9 Claims 1-6 wherein the means comprises an electronic, mechanical, magneti-c, optical, or 11 combination thereof, switch or trigger.

12 13 8. A semi-trailer assembly as clai-med in Claim 7 14 wherein the means comprises a roller valve means.

16 17 9. A semi-trailer assembly as claimed in any one of 18 the preceding Claims wherein t,-ie means act on a 19 fluid pressure system for supporting one or more of the pairs of wheels.

21 22 10. A semi-trailer assembly as claimed in Claim 9 23 wherein the pressurised fluid system is the main 24 pressurised fluid system of the trailer assembly.

26 27 11. A semi-trailer assembly as claimed in any one of 28 the preceding Claims wherein the means for 29 lowering and/or raising each pair of wheels actuates a separate container for pressurised 31 air at each relevant axle beam.

2 12. A semi-trailer assembly as claimed in any one of 3 the preceding Claims wherein the means causes 4 air flow to a pair of suspension bags supporting the relevant pair of wheels to be cut off and 6 exhaust to atmosphere and to divert air to one 7 or more axle lifting bags, as the trailer 8 retracts in a longitudinal direction.

9 13. A semi-trailer assembly as claimed in any one of 11 the Claims 9-12 which includes a valve system 12 for supplying pressurised fluid to the 13 pressurised fluid system of the trailer assembly 14 for the axle raising/lowering means.

is 16 14. A semi-trailer assembly as claimed in Claim 13 17 wherein the valve means comprises one or more of 18 the group comprising: pilot valve, push-pull 19 valve, roller valve, electrical solenoid valve, or electrical in-pulse valve.

21 22 is. A kit for application to an extendable trailer 23 chassis of a semi-trailer assembly comprising 24 means for automatically controlling the lowering and/or raising of at least one pair of wheels 26 supporting the chassis, upon retraction and/or 27 extension of the trailer chassis.

28 29 16. A kit as claimed in Claim 16 wherein the means acts on the most forward pair of wheels.

31 12 1 17. A semi-trailer assembly as substantially herein 2 described with reference to Figure 1.

3