Although this application refers almost exclusively to a coupling system for a cab unit and a trailer unit of an articulated lorry, it will be appreciated by persons skilled in the art that the coupling system could be used between any two or more units where mechanical, electrical and/or pneumatic coupling and uncoupling is required. For example, the coupling system could be used between a car and caravan, tractor and trailer or the like.

It is known in the art that a desirable feature of a coupling system is to provide service supply line connectors of a cab and trailer in such a manner that the connectors are readily connectable after the mechanical coupling between the fifth wheel and kingpin of a cab and trailer respectively has been established. In order to do this the service line connectors typically have to be in the vicinity of the kingpin and fifth wheel coupling. As such, the service line connectors need to be able to effect some rotary movement relative to each other to retain engagement therebetween during normal articulation movements of the vehicle during travel. The problems associated with this include the unreliability of the connection between the service line connectors and wear of the connector elements.

A solution to this problem is proposed in US3941408 wherein the service line connectors on the cab and trailer are provided on supports located a pre- determined distance apart from the fifth wheel coupling and the kingpin respectively. Mechanical engagement between the fifth wheel coupling and the kingpin actuates a further mechanism to allow engagement between the service supply line connectors. One or both of the cab or trailer supports are movable in a circular path about the axis of the kingpin and fifth wheel coupling when engaged, thereby allowing movement of the service line connectors during articulation of the vehicle. However, problems associated with this type of coupling system are the expense and large number of

components required in order to provide two separate engagement mechanisms ; one for'the mechanical engagement of the kingpin and fifth wheel and one for the engagement of the service line connectors. In addition, rotation between the service line connectors in this manner does not reduce wear therebetween or between the kingpin and fifth wheel coupling.

The above problem has been addressed in EP816211 which discloses a kingpin and fifth wheel coupling system wherein the service supply line connectors are provided in the kingpin and housing of the fifth wheel coupling. The kingpin is rotatably mounted on the trailer to allow correct alignment of the kingpin with the fifth wheel coupling during the coupling process. This coupling system however still suffers from the problem of requiring a large number of fragile components which are susceptible to wear and damage, particularly during rotation of the couplings. In addition, rotation of the kingpin relative to the housing results in large bending forces on the kingpin due to the leverage effect as the kingpin rotates.

The applicants co-pending International Patent application GB01/04626 discloses a coupling system overcoming the above problems. This coupling system comprises coupling means on a fifth wheel of a cab complementary to coupling means on a trailer in the form of a kingpin. The cab coupling means and kingpin have service supply lines provided therein to allow simultaneous or substantially simultaneous coupling of the service supply lines on mechanical coupling of the cab and trailer. The service supply lines once coupled allow the supply of services from the cab unit to the trailer unit and vice versa.

One of the cab coupling means or kingpin is provided with a number of annular protrusions on a coupling surface which engage with a corresponding number of complementary annular channels provided on the other of the cab coupling means or kingpin. The engagement of these annular protrusions/channels provide both mechanical engagement between the cab and trailer and allow the supply of services via the engaged annular channels/protrusions between the cab and trailer. The kingpin and cab coupling means are rigidly secured to the trailer and cab units respectively.

Rotation does take place between the cab and trailer due to rotation of the

annular protrusions in the annular channels during normal articulation of the cab and trailer. This rotation still results in some wear to the seals provided between the annular channels and protrusions ; which may result in damage and/or leakage to the sealed passageways formed therebetween.

It is therefore an aim of the present invention to provide improvements to coupling systems and particularly, but not exclusively to improvements to the coupling system described in GB01/04626.

According to a first aspect of the present invention there is provided a coupling system for a vehicle for coupling at least a cab unit to a trailer unit, said cab unit having coupling means provided on a fifth wheel of the cab which engage with complementary coupling means in the form of a kingpin on the trailer unit and characterised in that the cab coupling means is rotatably mounted with respect to the fifth wheel of the cab unit.

Thus by allowing the cab coupling means to rotate relative to the fifth wheel, the mechanical strain normally experienced between the annular grooves/protrusions, between the coupling surfaces of the kingpin and cab coupling means and/or any seals formed therebetween is reduced, if not completely eliminated. This in turn reduces the wear to the components of the coupling system.

Preferably the cab coupling means rotates relative to the fifth wheel during normal articulation of the vehicle. The kingpin is typically rigidly attached to the trailer unit, such that when the vehicle articulates the kingpin drives rotation of the rotatable cab coupling means.

Preferably the cab coupling means rotates about its central axis.

In one embodiment the cab coupling means is rotatably mounted to the fifth wheel via a bearing connection.

Preferably the bearing connection comprises a housing having a suitably shaped aperture in a base thereof. A base portion of the cab coupling means, which is of smaller dimensions than an upper portion of the cab coupling means, is located through the aperture. A shoulder portion formed between the base and upper portions of the cab coupling means sits in the base of the housing of the bearing connection and is freely rotatable therein.

Preferably anti-friction means are provided in or on the bearing housing such that friction between the bearing housing and the cab coupling means is significantly less than between any annular grooves and/or protrusions provided in the cab coupling means and kingpin. As such, the cab coupling means rotates in preference to any rotation at the coupling surfaces between the kingpin and cab coupling means. This reduces the wear on the coupling surfaces and components thereof.

Preferably the anti-friction means includes'needle'roller bearings and/or other conventional means.

Preferably the housing is securely attached to linear reciprocating means provided on the fifth wheel.

The linear reciprocating means allow the cab coupling means to be substantially vertically aligned with the kingpin prior to mechanical engagement/supply line connection and to raise and lower the cab coupling means for engagement with the kingpin.

Preferably the linear reciprocating means include a pneumatically driven arm or arms. The pneumatically operated arms raise and lower the cab coupling means towards and away form the kingpin. Thus engagement is effected between the two coupling units in a horizontal plane.

In one embodiment the cab coupling means or kingpin is provided with one or more annular protrusions on a coupling surface and the other of said cab coupling means or kingpin is provided with complementary annular channels on a coupling surface. The annular protrusions are received in the annular channels upon mechanical engagement of the cab coupling means and kingpin as described in co-pending application GB01/04626.

Preferably the service supply lines are provided between the cab and trailer units via the annular channels when engaged.

Preferably the cab coupling means and kingpin have one or more service supply lines provided therein. The service supply lines engage upon mechanical engagement of the cab coupling means and kingpin, thereby allowing the supply of services from said tractor unit to said trailer unit and/or vice versa. Thus the mechanical connection and the service line connections rotate together during articulation of the vehicle.

Further preferably one or more pneumatic supply lines are provided via the annular channels when engaged.

The annular protrusions can undergo a small degree of rotation in the annular channels if required. However, as rotation on the coupling surface typically results in wear, the provision of rotation of the cab coupling means relative to the fifth wheel significantly reduces the likelihood of rotation at the coupling surfaces. Thus the kingpin and cab coupling means rotate relative to the fifth wheel when securely engaged together.

Preferably sealing means are provided in or adjacent the annular protrusions and/or channels to allow sealed passages to be formed between the service supply lines of the cab and trailer units.

In one embodiment the sealing means form the annular channels and protrusions. In this embodiment the service supply line passages and/or channels in the kingpin and cab coupling means align on coupling of the respective couplings without engagement of annular protrusions/grooves.

The seals located adjacent the supply line passages prevent leakage of the service supplies therefrom.

The sealing means can be provided on the kingpin coupling surface, the cab coupling surface and/or both the kingpin and the cab coupling surfaces.

Preferably the annular passages provide pneumatic supplies between the cab and trailer.

Preferably sealing means are provided on one of the kingpin or cab coupling means only.

In one embodiment the sealing means are O-rings. In a further preferred embodiment the sealing means are stainless steel and/or silver plated seals of the type typically used in aero engines.

The coupling system of the present invention is capable of being operated by a driver within the tractor and/or trailer unit.

A plurality of facilities are typically provided on engagement of the cab and trailer coupling means. For example, the facilities can include operation of support legs on the cab and trailer units, operation of a brake system, and/or the like.

In addition, preferably signalling means are provided with the coupling system to indicate to a user/driver of the unit (s) that each or all of the coupling steps have been completed successfully. The signalling means can include any audio or visual signal such as one or more alarms or one or more lights. These signalling means can be displayed on a display panel in the cab or via speakers in the cab in response to a user request for the status of a function. The user request is typically actuated by depressing one or more switches on a control panel.

Preferably the signalling means also includes a quick release switch or security system.

The data required for operation of the plurality of facilities and/or signalling means typically has to be transmitted between the cab and trailer via the cab coupling means and kingpin.

Preferably the data can be transmitted between the cab and trailer units by any or any combination of a plurality of pins and corresponding recesses, electrical pulsed signals of a multiples system, fibre optic means, optical means, infra red means or radio waves means. For example, if a security system is employed via the coupling mechanism, when a user inputs a pin number or similar identification code into a control panel in the cab, this data is transmitted to a microprocessor and compared to a code, pin number or address provided by or detected via the kingpin. If an incorrect match is made between the identification code and the detected trailer code, coupling between the cab and trailer or operation of service supply lines therebetween will not be actuated. If a correct match is made between the cab and trailer unit, coupling and service supply between the cab and trailer is allowed to proceed.

In one embodiment the electrical connection between the trailer and tractor units is achieved by engagement of a plug in one of said cab coupling means or kingpin and a complementary socket in the other of said coupling means.

The electrical connection between the plug and socket can be via a plurality of electrical pins and corresponding recesses, electrical pulse signals of a multiplex system or via fibre optic or optic means. The data transmission

means. are preferably transmitted along the same passages provided for the electrical connections but they can be provided separately if required.

Preferably the electrical supply and data transfer links are arranged concentrically in the passageways of the kingpin and cab coupling means.

Preferably the electrical connection and/or data transmission connection is provided by a substantially centrally located conical, frustoconical or tapered protrusion on one of the cab coupling means or kingpin which engages with a complementary shaped recess on the other of the cab coupling means or kingpin. The protrusion and recesses both communicate with passageways in the respective couplings.

In a second aspect of the invention there is provided a coupling system for a vehicle for coupling at least cab unit to a trailer unit, said cab unit having coupling means provided in a housing on a fifth wheel thereof which engage with complementary coupling means in the form of a kingpin provided on said trailer unit, the cab coupling means and kingpin being provided with one or more annular channels on coupling surfaces thereof, the annular channels on the cab coupling means and kingpin being aligned on mechanical engagement of the cab coupling means and kingpin to form continuous sealed passageway (s) to allow the supply of one or more services between the cab and trailer units.

Preferably the cab coupling means is rotatably mounted relative to the fifth wheel. As the cab coupling means and kingpin rotate relative to the fifth wheel when engaged, alignment between the service supply lines is maintained during said rotation.

According to a further aspect of the present invention there is provided a fifth wheel for a cab unit, said fifth wheel having coupling means which engage with complementary coupling means on a trailer unit in the form of a kingpin, and characterised in that the cab coupling means is rotatably mounted on the fifth wheel of the cab unit.

According to a yet further aspect of the present invention there is provided a vehicle having a coupling system for coupling a cab unit to a trailer unit, said cab unit having coupling means provided on a fifth wheel of the cab which engage with complementary coupling means in the form of a kingpin

on the trailer unit and characterised in that the cab coupling means is rotatably mounted on the fifth wheel of the cab unit.

It will appreciated by persons skilled in the art that the present invention is equally applicable to a drawbar trailer coupling. The drawbar securing mechanism provided on a first trailer being equivalent to the fifth wheel mechanism on the cab unit and a coupling provided on a second trailer being equivalent to the kingpin of the first trailer.

The advantage of the present invention is that the ability of the cab coupling means to rotate relative to the cab reduces the wear on the seals between the cab coupling means and the kingpin and/or other components of the coupling system.

According to a yet further aspect of the present invention there is provided a locking mechanism for locking two coupling units of two respective vehicles together, said locking mechanism including a housing mounted on one of the vehicles, a port provided in the housing for the location of the two coupling units when coupled together, a locking member rotatably mounted on the housing, and drive means for driving the rotation of the locking member between a first locked position, wherein the locking member encloses an open portion of the port for securing the coupling units together, and a second unlocked position, wherein the locking member is removed from the open portion of the port for allowing release of the coupling units.

Preferably the locking member is a substantially semi-circular or"C"shaped member.

Preferably the locking member rotates through 180 degrees about the central axis of the coupling units when coupled together, between the unlocked and locked positions.

Preferably the drive means includes a worm drive which engages with a corresponding worm formation on the locking member. The worm drive is driven in a linear manner in a forwards and reverse direction. The formations on the worm drive/gear prevent movement other than the driven movement, thereby increasing the security of the lock and preventing the lock from becoming unlocked due to vibrations of the vehicles in transit.

The worm drive can be driven by any or any combination of manually, electrically, mechanically or pneumatically. In a preferred embodiment the worm drive is driven by an electric motor located in or adjacent the housing.

Preferably the pneumatic and electrical supplies are provided via the cab.

In one embodiment the two coupling units are a cab coupling means on a fifth wheel of the cab and a kingpin of a trailer. In this embodiment the housing of the locking member forms part of or is located on the fifth wheel of the cab.

In an alternative embodiment the two coupling units are drawbar couplings between first and second trailers. One of the coupling units is typically in the form of a kingpin and the other coupling unit is typically in the form of a cab coupling means.

Preferably a toggle switch mechanism is provided to allow reversal of the rotation of the locking member, thereby ensuring the locking member to move between locked and unlocked positions only.

An advantage of the third aspect of the present invention is the greater degree of security provided by the locking mechanism compared to that of conventional locks. In conventional locks the locking member and the housing does not completely encompass the coupling units in a locked position as it does in the present invention. In addition, with the present invention there is no requirement for any other locks or safety locking mechanisms, thereby increasing the ease of manufacture of the coupling units and reducing the cost of the same.

The present invention also extends to a vehicle with a locking mechanism and a fifth wheel with a locking mechanism.

Embodiments of the present invention will now be described with reference to the following Figures wherein:- Figure la is a plan view of the rotatable housing according to the present invention; Figure lb is a cross sectional view of the cab coupling means and trailer coupling means according to the present invention ; Figure lc is a detailed view of a section through the rotatable housing taken along line b-b in figure la ;

Figure I d is an enlarged view of the seals in figure lb ; Figures 2a-2b are simplified drawings of a coupling mechanism for a drawbar trailer according to a further embodiment of the present invention; Figure 3a is a plan view of a locking mechanism located on a fifth wheel according to a yet further embodiment of the present invention; Figure 3b is a simplified view of the locking mechanism in figure 3a; Figure 3c is a cross sectional view of the locking mechanism in figure 3a; and Figures 4a-c illustrate the arrangement of Figures 3a-c in a coupled position.

Referring to the figure lb, there is illustrated is a cross sectional view of cab coupling means 2 on the fifth wheel of a cab unit, and kingpin 4 of a trailer unit, when aligned prior to coupling.

The kingpin 4 is securely attached to trailer unit 5 by securing means in the form of bolts which pass between corresponding apertures 1 and 3 on the kingpin 4 and trailer unit 5 respectively.

In accordance with the present invention, cab coupling means 2 is rotatably mounted on a pneumatically controlled arm or arms 6 via a housing 8. The housing 8 is securely attached via screws 10 or other conventional securing means to arm 6 or is integrally formed therewith. The housing 8 is typically cylindrical in shape and a portion of the same sits in a complementary shaped port 12 of the free ends 14 of the arms 6.

Pneumatically operated arms 6 are actuated in use to raise and/or lower the cab coupling means 2 for coupling and uncoupling with the kingpin 4 in a substantially linear manner.

The housing 8 is in the form of an annular ring with side walls 9 and central aperture 9a. Friction reducing means in the form of needle roller bearings 16 are provided on the inner surface of the side walls.

The cab coupling means 2 comprises an upper portion 13 of larger dimensions than and a base portion 11, thereby forming a shoulder portion 15 therebetween. In assembled form, base portion 11 is located through aperture 9a and shoulder portion 15 engages with top surface 20 of the side walls 9 of the housing.

The coupling means 2 is freely rotatable in the housing 8 via the roller bearings 16, thereby allowing rotation of the cab coupling means 2 relative to the housing 8 and arms 6. As the kingpin 4 is securely attached to the trailer unit 5, when the cab and trailer are engaged and articulate during normal travel, the kingpin drives rotation of the cab coupling means 2, thereby reducing, if not eliminating, wear of the components on or adjacent the coupling surfaces 17, 19. The cab coupling means 2 and therefore the kingpin 4 rotate about axis'z', which is substantially central of the cab coupling means and kingpin.

The friction between the coupling surfaces 17 and 19 is significantly greater than the friction between the cab coupling means 2 and the housing 8, thereby allowing rotation of the cab coupling means relative to the fifth wheel of the cab in preference to rotation of the cab coupling means relative to the kingpin at the coupling surfaces 17,19.

Once the cab coupling means is located in the housing 8, a securing plate 22 is fitted to prevent removal of the cab coupling means from the housing during use. The securing plate 22 is detachably attached to the base 24 of the cab coupling means 2 via a threaded neck portion which cooperates with a corresponding threaded neck on base 24. The securing plate 22 can be unscrewed to allow the cab coupling means to be removed from the housing 8 for replacement and/or repair.

The securing plate 12 has a centrally located aperture 26 which passageway 28 is located substantially centrally thereof when the cab coupling means is assembled with the housing and securing plate. Hoses, which are conventionally rigidly connected to the coupling means 2, are rotatably mounted on the base 24 of the coupling means via pivotable castings 32 and can pass through the aperture 26 for central passageway 28. Hoses 30 are also provided to pass through aperture 26 and are connected to passageways 34 for providing a pneumatic supply (or other service supply) between the cab and the trailer. This allows the hoses to rotate when the cab coupling means 2 rotates relative to housing 8, thereby maintaining seals for the pneumatic hosing 30 and other service supply line connections during coupling and during rotation of coupling means 2.

The electrical supply between the cab and trailer units is provided through passageway 28 on the cab unit and passageway 106 on the trailer unit. End 36 of passageway 28 is shaped as a truncated cone having tapering side walls 38 which engages in a corresponding recess 114 at end 116 of passageway 106. The electrical supply is via pins on a plug and socket connection or other means as previously described above.

During coupling, end 36 of cab coupling means 2 is located in recess 114 of the kingpin and forms a sealed continuous passageway between 28 and 106 for the electrical supply between the cab and the trailer. The truncated cone shape of end 36 aids alignment in recess 114 during coupling.

In addition, passageway 28 and 106 can be used to transmit data between the cab and trailer relating to the coupling status and/or functional status of one or more operation systems. Thus for example, in order to operate any sequence of lights, anti-locking braking systems, a security system, support legs, kingpin and fifth wheel locking mechanisms, ancillary equipment and/or the like, a digital command signals are transferred between the cab unit and the trailer unit. Examples of the types of system that can be operated by a data transmission system are detailed in co-pending application GB/01/04626. The data transmission means and the electrical supply means are typically concentrically arranged in the passageways 106 and 28.

The data transmitted or transferred between the cab and trailer can be via a plurality of pins and corresponding recesses, electrical pulsed signals of a multiplex system, fibre optic means, optic means or radio waves. In this context, optical refers to light both in the visible and invisible spectra.

These data transmission means can be provided in separate passageways to the electrical supply but in order to reduce machining costs for machining two sets of passages, the data transmission means are typically provided in the same passageway as the electrical supply. Coding-decoding means, typically in the form of an analogue to digital converter, micro-processing means and/or the like are provided in the cab and/or trailer unit. A command signal is therefore transmitted or transferred between the cab unit to the trailer unit to operate various functions on the trailer unit via the

microprocessor (s). A confirmation of action signal is transmitted back from the units and is indicated, for example, by an illuminated light or audible signal in the cab of the vehicle.

For example, using radio wave methodology, one or more transmitters/receivers are provided in each of the cab and trailer units. Data is transmitted and received via radio waves and this information can be decoded in the cab by micro-processing means to inform a user in the cab of the operational status of a particular function requested by the user. A control unit, such as a display screen, can be provided in the cab on which to display the information relating to the transferred/transmitted data.

Coupling surface 19 of kingpin 4 is provided with a plurality of seals 118 and an enlarged view of the seals 118 is shown in figure ld. The seals 118 and 118'are provided either side of annular channels 108. A bleed hole 119 is provided between the two seals 118,188'which vents to atmosphere, such that if the seals degrade, there is no cross-contamination of service supplies between adjacent annular channels 108. This embodiment is particularly useful if different services are supplied via different annular channels.

Pneumatic supply passageways 34 in the cab coupling means open into annular channels 38 on the coupling surface 17 and pneumatic passageways 112 in the kingpin 104 open into the annular channels 108 on the coupling surface 19.

On engagement of the cab coupling means and kingpin, the annular channels 38 and 108, on the cab coupling means and kingpin respectively, are aligned and form continuous passageways therebetween. The seals 118, typically in the form of'O'rings or similar, are provided for the formation of continuous sealed passageways, thereby allowing pneumatic services to be provided from the cab unit via the annular channels to the trailer unit.

The'0'rings can be replaced by stainless steel and/or silver plated seals of the type typically used in aero engines. These types of seals are significantly more hard wearing than conventional seals used in vehicle coupling systems.

Referring to figures 2a and 2b, a coupling system in accordance with a further embodiment of the present invention is provided for a drawbar coupling. A cab unit 202 is coupled to a trailer unit 204 in the manner

described above using a fifth wheel and kingpin coupling mechanism between the cab and trailer units respectively at location or in a fixed position as shown. A second trailer 208 is coupled to the rear of the first trailer 204 via a drawbar coupling mechanism.

The drawbar 210 on the front of the second trailer 208 is provided with a kingpin coupling mechanism 212 as described in figures la-ld. The kingpin coupling 212 is attached to the drawbar 210 via a drawbar knuckle 214, the latter acting as a pivot to allow vertical movement during transit. Drawbar kingpin 212 is rigidly attached to flanges 211 and 213 of the drawbar.

A drawbar securing mechanism 216 in the form of a fifth wheel and cab coupling means 218 is provided adjacent the rear 220 of the first trailer unit 204. The cab coupling means is rotatably mounted relative to pneumatically operated arms 222 and drawbar securing mechanism 216. Engagement between coupling means 218 and drawbar kingpin 212 takes place in the manner as described above.

Thus it can be seen from the above description that the present invention provides improvements to a coupling system for reducing the wear and damage caused to components of the coupling system by rotatably mounting the cab coupling means to the fifth wheel.

In accordance with a yet further embodiment of the present invention there is provided a locking mechanism for a coupling system between two coupling units as illustrated in figures 3a-3c in an uncoupled condition and Figures 4a-c in a coupled position. For example, between a cab coupling unit and a trailer coupling unit as described above or in a conventional fifth wheel and kingpin coupling, or for a drawbar coupling mechanism.

Although this embodiment is described with reference to a drawbar coupling mechanism it will be appreciated by persons skilled in the art that the locking mechanism can apply to any of the abovementioned couplings.

The drawbar securing device 216 shown in figure 2b is illustrated in plan view in figures 3a and 4a. The device includes a catch housing 302 which is securely attached to the first trailer 204, a kingpin port 304 for location of a kingpin 312 as illustrated in Figures 4a-c for coupling to the first trailer, a worm driven'C'catch 306., an electric motor 308 and a worm drive 310.

The catch 306 is rotatably mounted on the catch housing to allow rotation relative thereto. The catch is rotated through 180 degrees between locked and unlocked positions to capture and uncapture the kingpin 312 respectively, as shown by arrow 314. This rotation is actuated by worm drive 310, which is driven by electric motor 308. Figures 4a and b illustrate the apparatus connected with the Figure 4a illustrating the apparatus in a straight configuration and Figure 4b illustrating the drawbar articulated 90 degrees with respect to the catch housing. Figure 4c illustrates the components of Figure 3c in a connected arrangement.

A cam profile 316, which is machined into the'C'catch, allows a toggle switch 318 to function at both ends of the 180 degrees range of rotation illustrated by reference numeral 320. In operation, the toggle switch isolates the motor 308 and changes the polarity of the same, thereby allowing the motor to drive the'C'catch in a reverse direction.

The'C'catch is secured to the catch housing 302 by virtue of the reduced diameter at the top of the catch and the securing plate below.

The ratio between the worm drive and the'C'catch is 40: 1 or greater. This prevents the'C'catch from driving the worm, thereby preventing the catch being released due to vibrations during transit of the vehicles/use of the coupling. As such, there is no requirement for additional locking mechanisms as there is with conventional couplings.