GB2167365A - A trailer coupling hitch - Google Patents

Abstract

A towing coupling for attachment to a towing vehicle comprises a mounting plate (11) at the forward end of the coupling, having a flat mounting surface and two spaced parallel apertures for receiving fixings perpendicular to the mounting surface, and first and second inclined jaws (17, 18) diverging rearwardly from the said mounting plate (11) and formed with respective aligned apertures (16, 22) for receiving a towing pin, a ball (25) for forming part of a ball and socket coupling surmounting a neck (24) projecting from one face (14) of the first jaw (17) wholly forwardly of the aperture (16) therein, this face (14) being substantially perpendicular to the mounting surface of the mounting plate (11). <IMAGE>

Description

SPECIFICATION An improved coupling hitch The present invention relates to a coupling hitch, and particularly to an improved coupling hitch by means of which a coupling can be made between a towing vehicle and a towed vehicle or trailer.

As used in this specification the term "trailer" will be understood to refer to any vehicle or implement which can be towed. In particular, the term "trailer" is to be taken to include agricultural implements which may or may not be fitted with wheels.

The prior art couplings for attachment of a trailer (as herein defined) to a towing vehicle include various different types of coupling which constitutes a disadvantage since any given towing vehicle can only be used to tow those trailers fitted with a cooperating coupling part of the same type as the hitch with which the towing vehicle is fitted. Two of the most common types of hitch known in the art are the so-called ball coupling, and the socalled tongue coupling. In the former, a ball is mounted on a neck securely fixed to the towing vehicle and a socket or cup is attached to the trailer.In the latter, one of the vehicles has a coupling comprising two spaced tongues or jaws with respective aligned apertures, and the other has a single tongue or ring with an aperture through which a pin can be passed, which pin also passes through the two aligned apertures in the jaw to effect a coupling.

In order to overcome the problem of having different trailers with different coupling attachments, it has been known in the art to provide a pin having a ball at one end, so that attachment may be made to the ball with cooperating cup or socket hitches, whilst a tongue or ring hitch can be fitted to the pin body. Such couplings have the disadvantage that the pin, which must be a sufficiently loose fit to be manually inserted and removed, allows the ball a certain free play which results in slack and vibration between the towing vehicle and the trailer, and also a certain amount of vertical movement which is undesirable.

In order to overcome this problem a unitary coupling comprising two parallel jaws and a ball mounted on a neck projecting up from the upper jaw was proposed in British Patent No.

1504643. This device had the disadvantage, however, that the necessary length of the jaw in order to provide sufficient space for mounting the ball limited the degree of relative vertical oscillation which could take place between the tractor and the trailer, for example, due to pitching movement of the trailer on rough ground or when changing levels, for example, to drive up and down a ramp, or even on the rapidly varying inclination of a hump-back bridge.

An attempt to overcome this problem was made with the device disclosed in British Patent application No. 2076765A which provided a towing coupling having a pair of inclined jaws allowing greater vertical oscillation, and having an integrally formed ball on the free end of the upper jaw. Although this device solved one of the problems inherent in the earlier design, the provision of the ball at the free end of the upper jaw made it necessary for this upper jaw to be of excessive thickness in order to accommodate the substantial strains imposed thereon when the ball coupling is used. Despite this excess thickening, there remains a substantial risk of fracture of the neck in the event of a "snatch" movement, for example, on rapid acceleration, deceleration or accidental impact.The present invention seeks to provide a towing coupling which will have all the advantages of the prior art coupling, particularly that disclosed in specification 2076765, namely the provision of short inclined jaws allowing a wide range of vertical oscillation, whilst nevertheless having an integrally provided ball coupling which is of great strength and rigidity and, likewise, is not subjected to fouiing by the jaws.

According to the present invention, therefore, a coupling hitch for attachment to a towing vehicle comprises spaced inclined upper and lower jaws formed with respective aligned apertures for receiving a towing pin and a bail for forming a ball and socket coupling with a cooperating socket on a trailer, the ball surmounting a neck projecting up from the upper jaw wholly forwardly of the said apertures with respect to the direction of movement of a towing vehicle having the hitch attached thereto. In this context it is anticipated that the jaws will face rearwardly of the vehicle and their spaced open ends be rearwardly located with respect to the attachment point for the towing hitch to the vehicle.

In the preferred embodiment of the invention the upper surface of the upper jaw is parallel to the lower surface of the lower jaw, whilst the upper surface of the iower jaw and the lower surface of the upper jaw are inclined with respect to one another. A reinforcing central web between the two jaws is preferably provided for added strength. Likewise, the lower jaw preferably has a reinforcing lower boss which may, in fact, be the component on which the lower surface is formed.

The inclined surfaces of the two jaws are preferably inclined by approximately 40 with respect to one another.

An embodiment of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of the embodiment; Figure 2 is an end view looking in the direction of the arrow A of Fig. 1; and Figure 3 is a perspective view of the embodiment.

Referring now to the drawings, the towing hitch illustrated has a mounting plate 11 at its forward end, for attachment to a suitable mounting bracket on the rear of the vehicle.

Projecting rearwardly from the mounting plate 11 is an upper jaw generally indicated 12 and a lower jaw generally indicated 13. The upper jaw 12 has a horizontal upper surface 14 and an inclined lower surdace 15 and a passage or aperture 16 orthogonal with respect to the upper surface 14 close to a free end 17 of the upper jaw itself. The lower jaw 13 has an upper surface 18 inclined at approximately 40 to the lower surface 15 of the upper jaw 12 and projecting from the lower surface 19 of the lower jaw 13 is a reinforcing boss 20, itself having a horizontal lower face 21 parallel to the upper face 14 of the upper jaw 12. An aperture or passage 22 passes through the lower jaw 13 and the boss 20, and is parallel to and aligned with the aperture 16 in the upper jaw 12.

A reinforcing web 23 spans the forward, closely adjacent portions of the inclined surfaces 15, 18 or the upper and lower jaws respectively.

From the upper surface 14 of the upper jaw 12 extends a neck 24 which is surmounted by a ball 25 having a part spherical surface and an undercut recess 26.

The mounting plate 11, as can be seed more clearly in Figs. 2 and 3, has two lateral fianges 27, 28 each of which has a respective aperture 29, 30 by means of which the hitch can be mounted to a towing vehicle.

In use of the hitch, the ball 25 may be used for engagement with a cup or socket of a ball hitch coupling of a trailer vehicle, whilst a ring or tongue may be introduced between the jaws 12, 13 and retained by a pin (not shown) passing through the aligned apertures 16, 22. The inclination of the jaws 12, 13 at their inner faces 15, 18 allows considerable vertical oscillation between the two components of the coupling to take place without any risk of fouling or contact and, as will be appreciated from Fig. 1, the substantial dimensions of the upper jaw 12 in the region where it merges into the neck 24 ensures that the whole body has considerable structural strength with no weak points.

One advantage of the towing hitch of the present invention resides in the inclination of the lower jaw 13 which is such that, when a pin is inserted through the aligned holes 16, 22 to retain a ring or other coupling attachment of a trailer, the weight on the ring applied by the trailer causes the ring itself to tend to slide down the inclined slope of the jaw 13 into contact with the pin reducing any tendency to slackness in the coupling.

Claims (12)

1. A towing coupling for attachment to a towing vehicle, comprising a mounting plate at the forward end of the coupling having a flat mounting surface and two spaced parallel apertures for receiving fixings perpendicular to the said mounting surface, and first and second inclined jaws diverging rearwardly away from the said mounting plate and formed with respective aligned apertures for receiving a towing pin, a ball for forming a ball and socket coupling surmounting a neck projecting from one face of the first jaw wholly forward of the aperture therein, the said one face being substantially perpendicular to the said mounting surface.

2. A towing coupling as claimed in Claim 1, in which the said first jaw is substantially triangular in axial section.

3. A towing coupling as claimed in Claim 1 or Claim 2, in which the said one face is an upper face in the orientation of use.

4. A towing coupling as claimed in any preceding Claim in which, the orientation of use, the upper surface of the top jaw is parallel to the lower surface of the bottom jaw.

5. A towing coupling as claimed in any preceding Claim, in which between the said first and second jaws there is a reinforcing central web the general plane of which lies parallel to the length of the jaws and the common axis of the aligned apertures in the jaws.

6. A towing coupling as claimed in any preceding Claim, in which the second inclined jaw has a reinforcing boss on the outer face thereof, that is the face directed away from the said first jaw.

7. A towing coupling as claimed in any preceding Claim, in which the faces of the two inclined jaws directed towards one another are inclined at an angle in the region of 40".

8. A towing coupling as claimed in any preceding Claim, in which the mounting plate, the jaws, the neck and the ball are all integrally formed as a single unitary element.

9. A towing coupling as claimed in any of Claims 6, 7, 8, in which the said reinforcing boss on the lower jaw has a transverse aperture therein for receiving an attachment device for securing a safety chain.

10. A towing coupling as claimed in any preceding Claim, in combination with a towing pin having an enlarged head at one end of produced axial length and an aperture extending transversely through the pin at or adjacent the other end for receiving a securing peg or pin, such as a linch pin.

11. A towing coupling as claimed in any of Claims 1 to 9, in which the aperture in the said first jaw has a counter bore in the face directed away from the other jaw whereby to receive at least part of an enlarged head of a pin passing through the two aligned apertures in the two jaws.

12. A towing coupling substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.