GB2612251A

GB2612251A - Automated heavy vehicle to trailer connection with integral electrical and pneumatic connection

Info

Publication number: GB2612251A
Application number: GB2301814.6A
Authority: GB
Inventors: Webster Gary; Keron Neil
Original assignee: Glic Ltd
Current assignee: Glic Ltd
Priority date: 2023-02-09
Filing date: 2023-02-09
Publication date: 2023-04-26
Anticipated expiration: 2043-02-09
Also published as: GB2612251B; GB202301814D0

Abstract

A hitch suitable for autonomous HGV trailer connection comprises a bracket mounted eye 3 with an opening (9 fig 6) for use on a trailer, and secondly a clevis assembly including pin 7, towing vehicle bracket, yoke 5 and recessed clevis 1 for accommodating eye 3. A vertical axis is for pin movement between a withdrawn position and a position extended into the recess and opening (9) to lock eye 3 in the clevis 1. The eye 3 can rotate about the axis. Relative rotation about a longitudinal axis can occur between yoke 5 and its bracket, and pivoting of clevis 1 is permitted relative to the yoke 5 about a transverse axis. Alternatively, equivalent eye rotation and/or pivoting may be provided. A cylindrical outer surface of the pin 7 is a close tolerance fit with the opening (9) so that relative movement between the pin 7 and eye 3 is possible about only one axis. Fluid communication ports and grooves, induction coils (34 fig 8) and/or electrical brush contact are preferably provided. The invention permits yaw, pitch and roll and pneumatic and electrical connection.

Description

AUTOMATED HEAVY VEHICLE TO TRAILER CONNECTION WITH

INTEGRAL ELECTRICAL AND PNEUMATIC CONNECTION

Field of the Invention

The invention relates to automatic hitching and unhitching of a heavy goods vehicle (HGV) to a trailer in a fully automatic way without the towing vehicle driver needing to leave the towing vehicle thus allowing fully autonomous connection of a heavy goods vehicle to a towed vehicle (trailer).

Background of the Invention

Heavy goods vehicles (towing vehicles) are sometimes used to tow unpowered vehicles (towed vehicles) such as trailers, gun carriages etc. The connection between towing vehicle and towed vehicle must accommodate (allow for) three types of relative motion between the towing vehicle and trailer, namely: 1 relative yaw motion which occurs when the towing vehicle is cornering. (motion around Y axis of figures 1 & 2) 2 relative pitch motion which occurs when the towing vehicle is cresting a hump or bottoming a trough. (motion around X axis of figures 1 & 2) 3 relative roll motion which occurs when one side of the towing vehicle climbs a bank which the trailer has not yet reached. (motion around Z axis of figures 1 & 2) Existing commercial heavy vehicle towing hitches typical employ a clevis I and towing pin 2 arrangement on the towing vehicle in conjunction with an eye 3 on the trailer. According to the prior art, relative pitch movement between the towing vehicle and trailer is accommodated by virtue of the towing pin 2 having a spherically curved surface 4. In conjunction with a significant clearance between the eye 3 and the spherically curved surface 4 of the towing pin (several millimetres) due to the the internal diameter of the eye being several millimetres larger than the outer diameter of the spherically curved surface 4 of the pin 2, this arrangement allows the eye to rotate with respect to the pin about both the X axis and the Y axis. The looseness of the interaction between eye and pin, necessary to allow movement about two axes, precludes transmission of any electrical or pneumatic services within the hitch.

According to the prior art, electrical power and pneumatic supply to the trailer are typically provided via separate cables and hoses which must be plugged manually in to sockets on the rear of the towing vehicle. These necessarily have slack in them to accommodate the change in length as the towing vehicle turns corners. If not managed properly the slack can drag on the ground and damage the hoses and cables. Furthermore, the plugs and sockets are difficult to keep clean when not connected.

Summary of the Invention

According to the present invention there is provided an automated system for hitching and unhitching a towing vehicle to a trailer including transmission of the electric power and pneumatic supply to the trailer.

More particularly, according to a first aspect of the present invention there is provided a tow hitch assembly comprising a first towing member which, in use, is fastened to one of a towing vehicle and a trailer, and a second towing member which, in use, is fastened to the other of the towing vehicle and the trailer;said second towing member including a towing eye having a through opening formed therein and a bracket for securing the second towing member to the other of said towing vehicle and the trailer; said first towing member comprising a bracket for securing the first towing member to said one of the vehicle and the trailer, a yoke connected to the bracket, a clevis which is connected to an end of the yoke remote from the bracket, the clevis including a recess in which, in use, is engageable the towing eye of the second towing member and a towing pin which is moveable along a vertical axis between a first position in which it is withdrawn from the recess so as, in use, to allow the towing eye to be inserted into or withdrawn from the recess, and a second positon in which it extends into said recess so as, in use, to engage the through opening in the towing eye and lock it in the clevis, said vertical axes define a pivot axis about which said towing eye can rotate about the pin which said pin is engaged in said through opening in said towing eye; one of said yoke and said towing eye being rotatably connected to its associated bracket so as to be rotatable about a longitudinal axis which extends through said one of the yoke and the towing eye and the associated bracket and, in use is parallel to the longitudinal axis of the towing vehicle or the trailer; and one of said clevis and said towing eye being pivotable relative to its associated bracket about a transverse axis which is perpendicular to said longitudinal axis and which in use, extends transversely to said longitudinal axis; wherein at least a part of said pin which, in use, locates within the through opening of said towing eye when in the second position, has a cylindrical outer surface which has a constant diameter and which is a close tolerance fit with the through opening in said towing eye such that the towing eye is substantially constrained to rotate only about said vertical axis.

A tow hitch assembly according to the first aspect of the invention has the advantage that the close tolerance bit between the towing eye and the pin keeps adjacent surfaces in a fixed position relative to each other, enabling transmission of services such as electrical and hydraulic or pneumatic supplies between the two parts Preferably said pin includes one of a port and a circumferentially extending groove formed in the outer surface of said part of said pin which, in use, locates within the through opening of said towing eye when in the pin is in the second position, and said towing eye includes one of a port and a circumferentially extending groove formed in the inner surface of said towing eye which, in use, aligns with said one of the port and circumferentially extending groove of the pin when said pin is in the second position so as to allow fluid communication therebetween, The or each circumferentially extending groove preferably extends around the entire periphery of the pin or towing eye in which it is formed The pin preferably has a circumferentially extending groove and said towing eye has a port. Sealing means, such as 0 rings may be provided on at least one of said pin and said towing eye for providing a fluid tight seal between said pin and said towing eye around the or each port and the or each circumferentially extending groove, preferably on either side of the or each circumferentially extending groove.

Each of said pin and said towing eye preferably includes a fluid supply passage, one end of which is in fluid communication with said one of said port or said circumferentially extending groove formed in each of said pin and said towing eye, the other end of each of which terminates in a connector for connecting fluid services thereto Said fluid supply passage in said pin is preferabnly formed by a first section which extends along the central axis of the pin from said connector to said part of said pin which, in use, locates within the through opening of said towing eye when in the pin is in the second position, and a second section which extends radially outwardly from said first section to said one of said port or said circumferentially extending groove formed in said pin.

Each of the pin and the towing eye may include multiple of said one of a port and a circumferentially extending groove, each said port or grove in the pin aligning with a corresponding port or groove in the towing eye so as to be in fluid communication therewith, each port or groove in each of the pin and the towing eye having an associated fluid supply passage connected to it which extends through the respective pin or towing eye.

Said pin preferably includes an electrical contact associated with the outer surface of said part of said pin which, in use, locates within the through opening of said towing eye when in the pin is in the second position, and said towing eye includes an electrical contact associated with the inner surface of said towing eye, said electrical contacts connecting, in use, when said pin is in the second position so as to allow fluid communication therebetween so as to enable electrical conduction therebetween.

At least one of said electrical contacts of said pin and said towing eye may extend circumferentially such that electrical contact is maintained as so towing eye rotates about said pin. The or each circumferentially contact preferably extends completely around the surface of said pin or towing eye with which it is associated.

One of said electrical contacts may comprises a brush which contacts said circumferentially extending contact as said towing eye rotates about said pin.

Each of said pin and said towing eye preferably includes an internal passage which extends at one end to said electrical contacts, electrical wires extending through said passages to connect to said contacts.

Each electrical contact is preferably mounted in a groove, which is in particular lined with insulating material, in its associated surface, said groove.

D

IN the preferred embodiment, said yoke of said first towing member is rotatably connected to the bracket so as to be rotatable about said longitudinal axis. Said clevis of said first towing member is furthermore preferably pivotally connected to said yoke so as to pivotable relative to the yoke about said transverse axis Said vertical axis is, in particular, longitudinally offset from said transverse axis. The end of the pin which passes through said through opening of said towing eye advantageously tapers inwardly to facilitate engagement of the pin with said through opening as said pin moves from said first position to said second position. This is particularly useful to ensure engagement if the towing eye is not fully located in the recess the tapered end ensuring that the pin engages the recess and pulls the towing eye fully into the recess.

Said towing eye is preferably a clearance fit in said recess in said first towing member such that that it is substantially prevented from vertical movement therein relative to said first towing member.

The present invention further provides a first towing member for a tow hitch assembly according to the invention, comprising a bracket for securing the first towing member, in use, to one of a vehicle and a trailer, a yoke connected to the bracket, a clevis which is connected to an end of the yoke remote from the bracket, the clevis including a recess in which, in use, is engageable a towing eye of a second towing member, and a towing pin which is moveable along a vertical axis between a first position in which it is withdrawn from the recess so as, in use, to allow the towing eye to be inserted into or withdrawn from the recess, and a second positon in which it extends into said recess so as, in use, to engage the through opening in the towing eye and lock it in the clevis, said vertical axes define a pivot axis about which, in use, said towing eye can rotate about the pin which said pin is engaged in said through opening in said towing eye, wherein at least a part of said pin which, in use, locates within the through opening of said towing eye when in the second position, has a cylindrical outer surface which has a constant diameter and which is a close tolerance fit with the through opening in said towing eye in which, in use, it engages, such that the towing eye is substantially constrained to rotate only about said vertical axis.

Said yoke is preferanly rotatably connected to said bracket so as to be rotatable about a longitudinal axis which extends through said yoke and said bracket and, in use is parallel to the longitudinal axis of the towing vehicle or the trailer to which the bracket is connected.

Said clevis is preferably pivotally connected to the yoke such that it is pivotable relative to the yoke about a transverse axis which is perpendicular to said longitudinal axis and which in use, extends transversely to said longitudinal axis.

The present invention still further provides a second towing member for a tow hitch assembly according to the invention, said second towing member including a towing eye having a through opening formed therein and a bracket for securing the second towing member, in use, to one of a towing vehicle and a trailer; said towing eye being size so as to be engageable, in use, in a recess formed in a clevis of a first towing member with said through opening aligned with a locking pin moveably mounted in said first towing member, and said through opening being sized so as to be a close tolerance fit around said locking pin when, in use, it is fully engaged in said through opening such that the towing eye is substantially constrained to rotate only about a central axis of said locking pin.

Brief Description of the Drawings

In order that the invention may be well understood, there will now be described some embodiments thereof, given by way of example, reference being made to the accompanying drawings, in which: Figure 1 is a section through a typical HGV tow hitch and trailer eye, according to the prior art; Figure 2 is a perspective view of towing vehicle clevis and trailer towing eye according to the present invention; Figure 3 is a section of towing vehicle clevis, towing pin and trailer towing eye according to the present invention; Figure 4 is a close-up section of towing vehicle clevis, towing pin and trailer towing eye according to the present invention; Figure 5 is a close-up section of the electrical contact and sealing 0-rings at the heart of the present invention; Figure 6 is a view and a section of trailer eye according to the present invention; Figure 7 is a transverse section through the towing vehicle clevis showing air passageways; Figure 8 is a section through a clevis, pin and eye of an alternative, inductive power transfer system according to another embodiment of the invention; and 205 Figure 9 is a vertical section through the present invention centred on the X axis,showing support pins 38 and bearings 39 which allow the clevis I to pitch relative to the yoke 5.

Table 1 provides a list of all reference numbers and their descriptive terms.

210 Table 1 Drawing item descriptions

Patent drwg no Description Shown in Figures

I Clevi s 2, 3.4, 5, 8,9

2 Towing pin according to the prior art 2

3 Trailer towing eye 2, 3, 4, 5, 8

4 Towing pin surface according to the prior art 1

-, Yoke 2,9 6 Horizontal pitch axis perpendicular to direction of vehicle travel 2 7 Towing pin according to the present invention 2, 3, 4, 5, 8 8 Air hole closing plug 4 9 Internal surface of trailer towing eye 6 Longitudinal axis of yoke 3 I I Yoke support bush 3 12 Towing vehicle rear beam 3 13 Vertical air hole through centre of towing pin 4,5 14 Air connection to towing vehicle air supply 2 Radial air hole through towing pin 4,5,7 16 Circumferential groove around towing pin 4,5,7 17 Air hole through trailer eye 3, 4, 5, 6 18 0-ring 5 19 0-ring 5 Trailer side air take-off point 6 21 Spring loaded electrical contact,.) 22 Insulated electrical cable carrying positive supply for towing vehicle 3, 4, 5 23 Cable hole through clevis 4, 5 24 Metallic electrical contact ring in trailer eye 6 Insulating sleeve for trailer eye contact ring 6 26 Trailer electrical off-take lead 6 27 0-ring 5 28 Towing pin pressure flange 7 29 0-ring 7 0 -ring 7 31 0-ring 7 31 Permanent magnet 5 32 Hall effect sensor it cable i, 33 Proximity sensor and cable 5 34 Primary induction coils 8 Primary cables 8 36 Secondary coils 8 37 Structural frame of towing vehicle 2 38 Support pins of pitch axis X 9 39 Bearings of pitch axis X 9

Detailed Description

With reference to Figures 2 to 9 of the drawings, there is shown a system for autonomous 215 hitching/unhitching of the clevis hitch of a towing vehicle to a trailer towing eye and the transfer of electrical and pneumatic power from towing vehicle to trailer.

Referring first to Figure 2, there is provided a yoke 5 which supports a clevis 1 such that the clevis t is free to rotate about a horizontal axis X which is perpendicular to the direction of travel, ie pitching between the vehicle and the trailer is accommodated by the clevis being 220 able to pitch with respect a fixed structural frame 37 of the towing vehicle. This is different from the prior art t shown in figure 1, wherein the clevis itself cannot pitch relative to the towing vehicle structure.

Mounted within the clevis is a towing pin 7. Unlike a towing pin according to the prior art, the towing pin of the present invention is straight sided (i,e of constant diameter) along its 225 entire length. The trailer towing eye 3 is similarly formed with a parallel sided towing hole 9 of an constant internal diameter which is only slightly larger (fractions of a millimetre) than the outside diameter of the towing pin 7 so as to be a clearance fit on the towing pin 7. As a result, the towing eye 3 of the trailer can rotate only about the vertical axis Y defined by the longitudinal axis of the pin 3, allowing relative yaw between vehicle and trailer.

230 IN order, then, to allow relative pitching movement between vehicle and trailer, the clevis 1 is pivotally mounted to the yoke 1 by means of transversely aligned rotation pins 38 which lie on a common axis X. As a result, the clevis 1 can rotate about the rotation pins 38 and hence the axis X, which thereby allows for pitching movement between trailer and vehicle despite the fact that towing pin 7 and eye 3 are a tolerance fit with each other and hence 235 allow only uni-axis rotational movement therebetween as compared with the prior art which allow dual axis rotation between towing pin and towing eye.

The third degree of movement required -relative roll between towing vehicle and trailer, is enabled in the same manner as the prior art by the yoke 10 being mounted in a support bush 11 fixed to the rear cross beam 12 of the towing vehicle so that the yoke 10 can rotate about 240 its longitudinal axis Z relative to the bush 11 and hence the vehicle, thereby allowing for roll between the vehicle and the trailer.

Note that in the preferred embodiment as illustrated in the Figures, the rotation pins 38 are set back from the towing pin 7 so that the X axis is offset from the Y axis. This allows a larger range of rotational movement of the towing eye 3 around the towing pin 7 (+/-80' 245 yaw motion) because opening in the clevis 1 through which the towing eye 3 extends to engage towing pin 7 can be made wider. However, a lesser range of yaw motion is acceptable, the rotation pins 38 could be provided at the ends of the opening in the clevis 1 so as to be aligned with the longitudinal axis Y of the towing pin 7, thereby having the X and Y axes intersecting This will enable the whole towing system to be more compact. It 230 will therefore be understood that the offset axes are not essential to the core operation of the present invention. It is the engagement of the towing eye with the towing pin in a close tolerance fit so as to allow only uni-axis rotation therebetween in combination with the clevis 1 being pivotally mounted to the yoke 5 to allow for pitching movement which is fundamental to the invention.

255 As a result of the towing pin being a close tolerance fit in the towing eye, it is possible to allow the rotational movement between the two parts whilst maintaining alignment between the two parts in all other planes This in turn allows transmission of services, such as pneumatic and electrical connections between the eye and the pin in a manner which has not been possible with the prior art.

260 As shown in Figure 3, towing pin 7 is provided with a central drilled hole 13 connected via a port 14 to the towing vehicle air supply. The top of the drilled hole includes a plug 8 to prevent escape of air. At an elevation corresponding to the centre of the trailer eye, the vertical air hole terminates where it intersects a hole 15 which extends radially from the centre of the towing pin to the circumference, which it intersects with a groove 16 which 265 extends circumferentially around the outside of thetowing pin 7. The circumferential groove 16 is located longitudinally on the pin 7 such that, when the towing pin 7 is in the closed position where it is engaged in the towing eye 3 of a trailer, the circumferential groove 16 aligns with a hole 17 which extends from the inner circumferential surface of the towing eye 3 longitudinally through a shaft which extends from the towing eye 3 towards the trailer.

270 Elastomeric sealing 0-rings 18 and 19 are set in to grooves in the towing pin above and below the circumferential groove 16 so as to ensure a fluid tight seal between the pin and the eye and thereby to prevent air leakage along the interface between towing pin and towing eye.

The arrangement of central hole, radial hole, circumferential groove, 0-rings and trailer 275 longitudinal hole thereby creates a fluid tight path for transmission of fluid such as pressurised air from the towing vehicle air supply to a take-off point 20 on the trailer. The circumferential extension of the groove 16 in the towing pin 7 ensures that the hole 17 in the towing eye 3 remains in fluid connection with the groove 16 as it rotates around the pin. Depending on the range of yaw movement, it may not be necessary for the groove 16 to 280 extend completely around the pin as long as any rotational movement of the pin 7 within the clevis 1 is restricted. It will also be recognised that the circumferential groove may instead be formed in the inner surface of the towing eye 3 rather than in the outer surface of the towing pin 7.

Electrical power is transferred from towing vehicle to trailer via a spring loaded electrical 285 contact 21 which projects from the outer circumferential surface of the towing pin. The electrical contact is connected to the towing vehicle positive electrical supply via an insulated cable 22 which extends through a vertical hole 23 formed in the clevis.

The trailer eye 3 then includes a metallic contact ring 24 set in a nylon or similar insulating ring 25 set within the inside surface of the eye. An insulated electrical off-take cable 26 is 290 in electrical contact with the ring and extends through to the surface of the towing eye 3 via a drilled hole. An 0-ring 27 is provided in a groove in the towing pin to provide a water tight seal above the electrical contact. Again, it will be recognised that the electrical spring contact may instead be provided on the inner circumferential surface of the towing eye 3 and the metal contact ring 24 mounted on the outer surface of the pin 7.

295 Return electrical path is provided by grounding both the trailer eye and the towing pin. A person skilled in the art will recognise that multiple air connections and/or multiple electrical paths could be incorporated in the pin/eye combination.

The parallel and close alignment of towing pin and trailer eye provide an opportunity for a second method of electrical power transfer. In this alternate embodiment, a set of electrically 300 conductive (typically copper) insulated coils 34 is mounted in a recess in the towing pin. For robustness, the coils may be embedded in a non-magnetic matrix such as epoxy resin. The coils are connected to an alternating current (AC) electrical source in the towing vehicle. A second set of coils 36 is set in a recess in the towing eye and connected to a control module on the trailer. Application of the alternating current in the primary coils will induce a voltage 305 in the secondary coils which is then converted to direct current by the trailer control module.

To improve magnetic coupling between primary and secondary coils, the coils may be magnetically insulated from the surrounding steel by a high magnetic permeability layer such as amorphous foil.

An advantage of inductive power transfer is that it is completely waterproof 310 In the present embodiment of the present invention, the upper section of the towing pin is utilised to lower and raise the towing pin during coupling and uncoupling. The towing pin is provided with a radial flange 28. The flange is provided with an 0-ring 29 to form an air tight seal with the inner wall of the clevis. 0-rings 30 and 31 are provided in the wall of the clevis to form an air tight seal between towing pin and clevis, and thereby formed a pressure 315 chamber therebetween. Towing vehicle air supply can be fed via ports the pressure chamber either above or below the flange 28 so as to either urge the flange and thereby the pin either downwards or upowards so as to move the pin between release and locked positions. Air supply is controlled by solenoid valves and a vehicle control module (not shown) It will be recognised by persons skilled in the art that there are other mechanisms which 320 could be deployed to raise and lower the towing pin. The present embodiment using towing vehicle air should in no way limit the invention.

Permanent magnets 31 are embedded in the towing pin to activate Hall Effect sensors 32 to inform the vehicle control module of the open and close positions of the towing pin.

A proximity sensor 33 is set in to the clevis to confirm the position of the trailer eye in the 325 clevis before closing of the towing pin by the vehicle control module It will be understood that, whilst the invention has been described with all the pivoting axes being provided on the clevis side of the couple, it is also possible that one or more of the pivot axes may instead be provided in the towing eye. For example, the towing eye may include a transverse pivot connection to its mounting bracket to accommodate pitch 330 movement within the coupling

Claims

Claims 1. A tow hitch assembly comprising a first towing member which, in use, is fastened to 335 one of a towing vehicle and a trailer, and a second towing member which, in use, is fastened to the other of the towing vehicle and the trailer, said second towing member including a towing eye having a through opening formed therein and a bracket for securing the second towing member to the other of said towing vehicle and the trailer; 340 said first towing member comprising a bracket for securing the first towing member to said one of the vehicle and the trailer, a yoke connected to the bracket, a clevis which is connected to an end of the yoke remote from the bracket, the clevis including a recess in which, in use, is engageable the towing eye of the second towing member and a towing pin which is moveable along a vertical axis between a first position in which it is withdrawn 345 from the recess so as, in use, to allow the towing eye to be inserted into or withdrawn from the recess, and a second positon in which it extends into said recess so as, in use, to engage the through opening in the towing eye and lock it in the clevis, said vertical axes define a pivot axis about which said towing eye can rotate about the pin which said pin is engaged in said through opening in said towing eye; 350 one of said yoke and said towing eye being rotatably connected to its associated bracket so as to be rotatable about a longitudinal axis which extends through said one of the yoke and the towing eye and the associated bracket and, in use is parallel to the longitudinal axis of the towing vehicle or the trailer; and one of said clevis and said towing eye being pivotable relative to its associated 355 bracket about a transverse axis which is perpendicular to said longitudinal axis and which in use, extends transversely to said longitudinal axis; wherein at least a part of said pin which, in use, locates within the through opening of said towing eye when in the second position, has a cylindrical outer surface which has a constant diameter and which is a close tolerance fit with the through opening in said towing eye such 360 that the towing eye is substantially constrained to rotate only about said vertical axis.
2. A tow hitch assembly according to claim I, wherein said pin includes one of a port and a circumferentially extending groove formed in the outer surface of said part of said pin which, in use, locates within the through opening of said towing eye when in the pin is in 365 the second position, and said towing eye includes one of a port and a circumferentially extending groove formed in the inner surface of said towing eye which, in use, aligns with said one of the port and circumferentially extending groove of the pin when said pin is in the second position so as to allow fluid communication therebetIveen, 370
3. A tow hitch assembly according to claim 2, wherein the or each circumferentially extending groove extends around the entire periphery of the pin or towing eye in which it is formed.
4. A tow hitch assembly according to claim 2 or claim 3, wherein said pin has a 375 circumferentially extending groove and said towing eye has a port.
5. A tow hitch assembly according to any of claims 2 to 4, further including sealing means provided on at least one of said pin and said towing eye for providing a fluid tight seal between said pin and said towing eye around the or each port and the or each 380 circumferentially extending groove
6. A tow hitch assembly according to according to claim 5, wherein said seal means comprises o-ring seals carried in the surface of at least one of the pin and the towing eye on either side of the or each circumferentially extending groove.
7. A tow hitch assembly according to any of claims 2 to 6, wherein each of said pin and said towing eye includes a fluid supply passage, one end of which is in fluid communication with said one of said port or said circumferentially extending groove fonned in each of said pin and said towing eye, the other end of each of which terminates in a connector for 390 connecting fluid services thereto.
8. A tow hitch assembly according to claim 7, wherein said fluid supply passage in said pin is formed by a first section which extends along the central axis of the pin from said connector to said part of said pin which, in use, locates within the through opening of said 395 towing eye when in the pin is in the second position, and a second section which extends radially outwardly from said first section to said one of said port or said circumferentially extending groove formed in said pin
9. A tow hitch assembly according to any of claims 2 to 8, wherein each of the pin and 400 the towing eye includes multiple of said one of a port and a circumferentially extending groove, each said port or grove in the pin aligning with a corresponding port or groove in the towing eye so as to be in fluid communication therewith, each port or groove in each of the pin and the towing eye having an associated fluid supply passage connected to it which extends through the respective pin or towing eye.
10. A tow hitch assembly according to any of the previous claims, wherein said pin includes an electrical contact associated with the outer surface of said part of said pin which, in use, locates within the through opening of said towing eye when in the pin is in the second position, and said towing eye includes an electrical contact associated with the inner surface 410 of said towing eye, said electrical contacts connecting, in use, when said pin is in the second position so as to allow fluid communication therebetween so as to enable electrical con ducti on therebetween.
11 A tow hitch assembly according to claim 10, wherein at least one of said electrical 415 contacts of said pin and said towing eye extend circumferentially such that electrical contact is maintained as so towing eye rotates about said pin.
12. A tow hitch assembly according to claim 11, wherein the or each circumferentially contact extends completely around the surface of said pin or towing eye with which it is 420 associated.
13. A tow hitch assembly according to claim 11 or claim 12, wherein one of said electrical contacts comprises a brush which contacts said circumferentially extending contact as said towing eye rotates about said pin.
14. A tow hitch assembly according to any of claims 10 to 13, wherein each of said pin and said towing eye includes an internal passage which extends at one end to said electrical contacts, electrical wires extending through said passages to connect to said contacts.430
15. A tow hitch assembly according to any of claims 10 to 14, wherein each electrical contact is mounted in a groove in its associated surface, said groove preferably being lined with insulating material to electrically isolated each said contact from the material of the surface with which it is associated 435
16 A tow hitch assembly according to any of the preceding claims, wherein said yoke of said first towing member is rotatably connected to the bracket so as to be rotatable about said longitudinal axis.
17. A tow hitch assembly according to any of the preceding claims, wherein said clevis 440 of said first towing member is pivotally connected to said yoke so as to pivotable relative to the yoke about said transverse axis.
18 A tow hitch assembly according to any of the preceding claims, wherein said vertical axis is longitudinally offset from said transverse axis.
19. A tow hitch according to any of the preceding claims, wherein the end of the pin which passes through said through opening of said towing eye tapers inwardly to facilitate engagement of the pin with said through opening as said pin moves from said first position to said second position.
20. A tow hitch assembly according to any of the preceding claims, wherein said towing eye is a clearance fit in said recess in said first towing member such that that it is substantially prevented from vertical movement therein relative to said first towing member.455
21. A first towing member for a tow hitch assembly according to any of the preceding claims, comprising a bracket for securing the first towing member, in use, to one of a vehicle and a trailer, a yoke connected to the bracket, a clevis which is connected to an end of the yoke remote from the bracket, the clevis including a recess in which, in use, is engageable a towing eye of a second towing member, and a towing pin which is moveable along a vertical 460 axis between a first position in which it is withdrawn from the recess so as, in use, to allow the towing eye to be inserted into or withdrawn from the recess, and a second positon in which it extends into said recess so as, in use, to engage the through opening in the towing eye and lock it in the clevis, said vertical axes define a pivot axis about which, in use, said towing eye can rotate about the pin which said pin is engaged in said through opening in said 465 towing eye; wherein at least a part of said pin which, in use, locates within the through opening of said towing eye when in the second position, has a cylindrical outer surface which has a constant diameter and which is a close tolerance fit with the through opening in said towing eye in which, in use, it engages, such that the towing eye is substantially constrained to rotate only 470 about said vertical axis.
22. A first towing member according to claim 21, wherein said yoke is rotatably connected to said bracket so as to be rotatable about a longitudinal axis which extends through said yoke and said bracket and, in use is parallel to the longitudinal axis of the towing 475 vehicle or the trailer to which the bracket is connected.
23. A first towing member according to claim 20 or claim 21, wherein said clevis is pivotally connected to the yoke such that it is pi votable relative to the yoke about a transverse axis which is perpendicular to said longitudinal axis and which in use, extends transversely 480 to said longitudinal axis.
24. A second towing member for a tow hitch assembly according to any of claims 1 to 20, said second towing member including a towing eye having a through opening formed therein and a bracket for securing the second towing member, in use, to one of a towing 485 vehicle and a trailer; said towing eye being size so as to be engageable, in use, in a recess formed in a clevis of a first towing member with said through opening aligned with a locking pin moveably mounted in said first towing member, and said through opening being sized so as to be a close tolerance fit around said locking pin when, in use, it is fully engaged in said through opening such that the towing eye is substantially constrained to rotate only 490 about a central axis of said locking pin.