GB2037684A - Improvements in or relating to tractor vehicles - Google Patents

Abstract

A vertically adjustable fifth wheel coupling arrangement is proposed wherein the rearward end of a framework (12) is pivotally secured to the tractor chassis (13) for motion about an axis (14) extending widthwise of such chassis, the coupling plate (33) being supported on and by the framework in the central region thereof, and a lifting means (15) is provided operable between the chassis (13) and the forward end of the framework (12) for effecting pivotal motion of the framework and the raising and lowering of the coupling plate (33). Guide bars (30) are provided on the framework and depend therefrom for co-operation with the chassis, and support the framework against transverse loads. A fail-safe device is also included for preventing disengagement of the coupling parts when the coupling plate is in an elevated position. <IMAGE>

Description

SPECiFICATION Improvements or in relating to tractor vehicles The invention concerns improvements in or relating to tractor vehicles, and has more particular reference to fifth wheel couplings of such vehicles.

Fifth wheel couplings for connecting together tractor/trailer combinations are well known and have been widely used for very many years, such couplings usually comprising a plate mounted on the tractor vehicle and adapted to receive a depending pin at the forward end of the trailer into engagement with openable jaws provided at the inner end of a V-shaped entrance opening in the plate, the plate being generally circular and the jaws being located centrally thereof.

It is known to mount the plate for limited motion about an axis extending transversely of the tractor vehicle, and to provide an inclined surface to such plate in the region of the entrance opening therein to provide a ramp effect for facilitating engagment of the plate with the forward end of the trailer and of the pin with the entrance opening.

United States Patent Specification No. 2,667,363 discloses a fifth wheel coupling of the aforesaid kind wherein the plate is adjustable as regards its vertical position on the tractor, such plate being mounted on and centrally of a cranked support bar of which one end is pivotally connected to the tractor chassis at the rearward end thereof and of which the other end is attached to the connecting rod of an hydraulic cylinder arrangement for vertical adjustment by such arrangement.

Means are provided on the support bar and tractor chassis for securing such support bar, and hence the fifth wheel coupling plate, at a predetermined disposition such means comprising an upwardly extending ear at the forward end of the support bar arranged in adjacent disposition relative to a lug on the chassis and coupled thereto by a bolt engaged with an elongate slot therein.

The tractor/trailer combination as disclosed in U.S.

Specification No. 2,667,363 is specifically intended for use in the context of low-bed, heavy duty trailers for the transportation of heavy machinery such as power-shovels, bulldozers and other earth working and moving machinery, and is designed accordingly.

Thus, whilst no doubt eminently suitable for use in the aforesaid context, the lifting fifth wheel coupling proposed is of only limited use in conventional tractor/trailer combinations for normal road usage, having regard to the dynamic forces to which couplings as used in such context are subjected.

In order to maximisethe utilisation of tractor vehicles it is necessary that such tractor vehicles be capable of being coupled to trailer front ends of different heights. Whilst the fifth wheel coupling arrangement of U.S Specification No. 2,667,363 can clearly be used in conjunction with trailers having front ends of different heights, in that the coupling arrangement is itself adjustable as to height in addition to the coupling plate being pivotable within limits, the range of possible heights is restricted by virtue of the very form of the arrangement.

The primary object of the present invention is to provide means whereby the range of trailer front end heights with which the fifth wheel coupling is co-operable is maximised.

According to the present invention a fifth wheel coupling arrangement for a tractor vehicle comprises a framework mounted on the said vehicle for pivotal motion about a transverse axis adjacent the rear end of said vehicle, a coupling plate pivotable on such framework about an axis transverse to the vehicle, lifting means connected with an operable between the chassis and the framework forwardly of the coupling plate and adapted, upon operation, to pivot the framework about the pivot axis thereof, and ramp means on the framework and extending upwardly and forwardly thereof towards the coupling plate.

According to a preferred feature, the arrangement further includes guide bars secured to the framework and depending therefrom, the said guide bars being in sliding engagement with the chassis and being adapted to sustain the framework against lateral loads.

According to a still further preferred feature, the arrangement also includes means adapted to preclude opening of the jaws of the coupling plate when the latter is in a raised position.

The invention will now be described further, by way of example only, with reference to the accompanying drawings in which: Figure lisa diagrammatic perspective view of a fifth wheel coupling arrangement constructed in accordance with the invention as applied to a tractor vehicle; Figures 2a and 2b are diagrammatic side elevations of the arrangement shown in Figure 1 and illustrate the lowermost and uppermost positions of the coupling plate; and Figures 3a and 3b are diagrammatic side elevations of a part of a lifting fifth wheel coupling of the kind shown in Figure 1 and illustrate a cut-off device for preventing opening of the coupling jaws in the raised condition of the coupling plate.

Referrring now to the drawings, a fifth wheel coupling arrangement for a tractor vehicle comprises a generally rectangular framework 11 pivotally mounted at the trailing end 12 of a tractor chassis 13 for motion about an axis 14 extending transversely of such chassis under the control of fluid-operated piston and cylinder means 15 secured to and extending between the forward end of the framework and a depending cradle 16 attached to such chassis.

The framework includes spaced side members 17 arranged in aligned overlying disposition relative to corresponding elements 18 of the tractor chassis, and spaced transverse elements 19, 20, 21 extending between such members at forward, rearward and intermediate positions, respectively, thereon. Forward element 19 is of angle section and is secured to the forward ends of side members 17 in abutting disposition relative thereto, the free web of such element being horizontally disposed and being generally co-planar with the plane defined by the top surface of the framework. Support lugs 22 are provided on the angle section element 19 to receive the upper end of a piston 23 of a respective one of the piston and cylinder means 15. Intermediate element 20 is of rectangular cross-section, and is located approximately midway between the ends of the side members.Rearward element 21 is likewise of rectangular cross-section and is secured to the underside of the side members at the rearward end thereof. Stub axles 24 are provided at the underside of the rearward transverse element 21, such axles extending outwardly of the framework for cooperation with respective bearing plates 25 provided on the chassis.

The depending cradle 16 comprises side members 26 secured to the chassis and depending therefrom, the lower ends of such members 26 being connected by spaced, outwardly facing channel members 27 secured thereto, there being pairs of mounting plates 28 extending between the adjacent webs of the channel members 27 to which the lower ends of respective cylinders 29 of the piston and cylinder means are secured, the pistons 23 of such means being connected with lugs 22 on the forward transverse element 19 as above mentioned.

As will be appreciated, upon actuation of the piston and cylinder means 15 the platform will be pivoted about the axis as defined by the stub axles 24.

Guide bars 30 are provided on the framework, such guide bars being secured to the outer faces of the side members 17 and depending from such members to lie in closely spaced adjacent disposition relative to the corresponding ones of the chassis elements 18. The guide bars 30 co-operate with the chassis and serve to support the platform against transverse dynamic loads as applied to the platform.

Ramp means 31 are provided on the framework adjacent the rearward end thereof, such means comprising ramp members 32 mounted on the respective side members slightly forwardly of the rear extremities thereof, the said ramp members having forwardly and upwardly directed support surfaces which form forward extensions to inclined surfaces provided on the rear ends of the side members by bevelling such rear ends.

Afifth wheel coupling plate 33 is mounted on the framework slightly forwardly of the intermediate transverse element 20, the plate 33 being supported in journals 34 secured to the upper face of the respective side members for limited pivotal motion about an axis extending transversely of the framework The rearward end of the plate 33 is bevelled to facilitate engagement thereof with the underside of the forward end of a trailer.

As will be appreciated, when disposed parallel to the plane of the framework the rearward end of the plate lies below the level of the upper end of the ramp members 32, and thus such ramp members 32 serve to lift the forward end of a trailer into position for engagement of the depending coupling pin (not shown) with the V-shaped lead-in channel on the coupling plate and, eventually, with the coupling jaws.

As will be appreciated, by providing a ramp means the lower end of which is at a lower level than the rearmost part of the coupling plate so we are able to effect coupling between a tractor and a trailer of which the forward end is lower than the coupling plate. The lift facility of the coupling plate provides for the use of the fifth wheel coupling with trailers of which the forward end is normally at a higher level and the lowest level of the coupling plate. Accordingly, the arrangement as herein proposed may be used with a range of trailers. The inclusion of guide bars of the kind and for the purpose disclosed avoids undue dynamic loads being applied to the framework and the support or mounting means therefor.

By locating the pivot axis of the framework and the line of action of the piston and cylinder means in alignment with the support positions of the trailer suspension, further advantageous operation of the trailer coupling is achieved.

A further important feature of the invention is the provisions of means for locking the pin of the trailer in its position of engagement with the coupling jaws when the fifth wheel coupling is in an elevated position. It is proposed that a valve be provided in the fluid system to the coupling jaws which is sensitive to the position of the framework relative to the tractor chassis and which, according to the relative position of such structures precludes the opening of such jaws.

A typical arrangement is shown in Figures 3a, 3b and will be seen to comprise a valve 35 operable by a plunger 36 in the path of movement of the framework 11, the valve 35 closing to isolate chamber 37 in the control circuit operating the locking mechanism of the jaws on lift of the framework thus to leave the jaws fully closed. On lowering of the framework the plunger 36 operates the valve 35 thus to allow of the application of air under pressure to pistons (not shown) controlled by chamber 37 whereby the jaws are opened as required. Alternative means for effecting a like control will readily present themselves to one skilled in the art.

Claims (16)

1. A fifth-wheel coupling arrangement for a tractor vehicle comprising a framework mounted on the said vehicle for pivotal motion about a transverse axis adjacent the rear end of said vehicle, a coupling plate pivotable on such framework about an axis transverse to the vehicle, lifting means connected with and operable between the chassis and the framework forwardly of the coupling plate and adapted, upon operation, to pivot the framework aboutthe pivot axis thereof, and ramp means on the framework and extending upwardly and forwardly thereof towards the coupling plate.

2. A coupling arrangement as claimed in claim 1, further including guide bars secured on the framework and depending therefrom, the said guide bars being in sliding engagement with the chassis and being adapted to sustain the framework against lateral loads.

3. A coupling arrangement as claimed in claim 2, wherein the said guide bars are each located outwardly of and adjacent to a respective longitudinal chassis member.

4. A coupling arrangement as claimed in any one of the preceding claims, wherein the framework includes spaced, parallel side members arranged in overlying disposition relative to a respective longitudinal member of the vehicle chassis.

5. A coupling arrangement as claimed in claim 4, wherein the ramp means comprises a respective ramp member provided on each said side member against the rearward end thereof.

6. A coupling arrangement as claimed in claim 5, wherein each ramp member is positioned in spaced disposition from the rearward extremity of its respective side member, and the upper surfaces of the said side members are downwardly and rearwardly inclined between the ramp members and the said rearward extremities.

7. A coupling arrangement as claimed in claim 6, wherein the inclined upper surfaces of the side members are coplanar or substantially copolanar with the upper surfaces of the ramp members.

8. A coupling arrangement as claimed in any one of the preceding claims, including a cradle secured to the chassis and depending therefrom, the lifting means being operable between said cradle and framework.

9. A coupling arrangement as claimed in claim 8, wherein the cradle is secured to the chassis substantially in register with the forward end of the framework, and the lifting means are coupled to the framework at such forward end.

10. Acoupling arrangement as claimed in any one of the preceding claims, wherein the coupling plate includes openable jaws for receiving the depending pin of a fifth wheel coupling into captive engagement therewith, operating means adapted upon actuation to open the said jaws for release of the pin, and control means sensitive to the angular position of the framework and adapted to renderthe operating means inoperative in raised positions of the framework.

11. A coupling arrangement as claimed in claim 10, wherein the operating means includes a pressure fluid system adapted on actuation to apply fluid under pressure to release the jaws and the control means includes a fluid flow valve in such system and adapted to isolate such fluid from the jaws in raised positions of the framework.

12. A coupling arrangement as claimed in claim 11, wherein the fluid flow valve includes an operating plunger in the path of movement of the framework, the said plunger being maintained in a position corresponding to an open position thereof by the framework in the lowered position of the said framework.

13. A coupling arrangement as claimed in claim 11 or 12, wherein the pressure fluid system is a compressed air system.

14. Acoupling arrangement substantially as hereinbefore described with reference to and as illustrated in the various figures of the accompanying drawings.

15. Atractorvehicle including a coupling arrangement as claimed in any one of the preceding claims.

16. Atractor/trailer combination including a cou