GB2495940A

GB2495940A - Kickout reduction mechanism for trailer rear steering

Info

Publication number: GB2495940A
Application number: GB201118440A
Authority: GB
Inventors: Gerald Muldoon
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-10-25
Filing date: 2011-10-25
Publication date: 2013-05-01
Anticipated expiration: 2031-10-25
Also published as: GB2495940B; GB201118440D0

Abstract

A kickout reduction mechanism is provided for least one pair of passively steerable wheels of an articulated vehicle, wherein a trailer 2 is towed by a tractor unit via a fifth wheel 5 and kingpin 6. The mechanism comprises selectively operable retaining means for retaining the passively steerable wheels in a straight ahead. position under predetermined circumstances. In particular, the mechanism comprises a pneumatic actuator 10 having a projecting pin 12 defining a retaining member terminating in an engageable roller (14 see fig 2a). The invention is particularly useful at roundabouts and for long vehicles where the rear wheels are prevented from prematurely being steered by an undesired amount.

Description

Kickout reduction mechanism for a rear wheel steerin2 system of a trailer This invention relates to a kickout reduction mechanism for a rear wheel steering system of a trailer and to a passive rear whccl steering system incorporating such ldckout reduction mechanism.

Articulated tractor-semi-trailer combinations are extensively used in the haulage industry to transport goods on the road network. Semi-trailers having a trailer length of over 12 metres arc quite common. Tn addition, proposals have been made to permit the use of trailers even exceeding this length. When such long tractor-trailer combinations are used on motorways, no particularly significant problems arc encountered, since the lanes are wide, and the curves arc large radius curves. When the tractor-trailer combination, particularly for such long trailers, is operated on city streets and roundabouts. However, the relatively narrow width and tight radius of many streets and roundabouts makes it very difficult or impossible to manoeuvre the tractor-trailer through turns. The rear wheels of the trailer unit do not track the wheels of the tractor unit, but tend to be considerably offset, particularly in sharp turns, as the tractor manoeuvres through a turn.

One way of alleviating this problem is to provide a steerable rear axle on the trailer. Such steerable rear axle may be an active system, as disclosed in WO 98/21082, wherein the rear wheels of the trailer arc steering via a linkage arrangement coupled to the fifth wheel of the tractor unit, or by a passive system, wherein the rear wheels of the trailer are free to steer and arc returned to a central position via a castor effect, wherein the steering axis of the each rear wheel lies ahead of the contact point of the wheel on the ground, the wheels naturally following the curvature of the bend followed by the vehicle.

However, even trailers having such steerable rear axles, in particular having such passive rear wheel steering systems, can encounter problems where trailer length exceeds 12 metres.

When approaching a roundabout, a trailer over 15.5 metres long must be able to turn on either lock so that no part of it projects outside the area contained between two concentric circles of 5.3m and l2.5m radii. This is particularly difficult to achieve when the trailer begins its turn in conjunction with the driving cab. The back end of the trailer easily protrudes beyond said area as soon as the lorry begins its turn, a process known as kickout".

An object of the present invention is to provide an improved passive rear wheel steering system having a kickout reduction mechanism intended to alleviate such problem.

According to a first aspect of the invention there is provided a kickout reduction mechanism for least one pair of passively steerable wheels of a vehicle, more preferably an articulated vehicle, comprising trailer towed by a tractor unit via a fifth wheel assembly on the tractor unit, said mechanism comprising selectively operable retaining means for retaining the at least one pair of passively steerable wheels in a straight ahead position under predetermined circumstances, such as during initial tuming of the vehicle from a straight ahead position.

In one embodiment said retaining means is adapted to retain the at least one pair of passively steerable wheels in a straight ahead position during Limited rotary movement of the fifth wheel of the tractor unit with respect to the trailer during initial steering of the tractor unit away from a straight ahead position. Preferably said retaining means is adapted to release said least one pair of steerable rear wheels when said rotary movement of the trailer with respect to the fifth wheel of the tractor exceeds a predetermined angle. Additionally, or alternatively said retaining means may be adapted to retain the at least one pair of steerable rear wheels in a straight ahead position during reversing of the articulated vehicle.

Additionally, or alternatively said retaining means may be adapted to retain the at least one pair of steerable rear wheels in a straight ahead position when the speed of said articulated vehicle exceeds a predetermined maximum speed above which operation of the passive steering system is undesirable.

In one embodiment said retaining means includes a retaining member moveable between an operative position, wherein said retaining member retains the at least one pair of steerable rear wheels in said straight ahead position, and an inoperative position, wherein said at least one pair of steerable wheels are free to be steered.

Said retaining member may comprise a projection adapted to engage a recess provided on a moveable part of the rear wheel steering system to lock said rear wheel steering system in a straight ahead position when said retaining member is in its operative position, such that the projection is received within said recess. Said projection may include a roller to facilitate movement of said projection into and out of said recess. Said recess may comprise a base and sloping side walls extending outwardly from the base, for example extending at an angle of around 45° to the base, to facilitate movement of the roller into and out of the recess.

In one embodiment said retaining member is urged towards its operative position by biasing means, such as a spring, actuating means being provided for selectively urging said retaining member to its operative position to enable steering of the at least one pair of steerable rear wheels Tn an alternative embodiment said retaining member is urged to, and maintained in, its operative position by actuating means, said actuating means being operable to maintain said retaining member in said engaged position, said retaining member being free to return to its disengaged position when said actuating means is deactivated, for example in response to movement of the fifth wheel of the tractor unit relative to the trailer exceeding said predetermined angle. Biasing means, such as a spring, may be provided for urging said retaining member towards its inoperative position following deactivation of said actuating means. Alternatively, or additionally, said retaining member may be urged towards its inactive position by said sloping walls of the recess.

Said actuating means may comprise a hydraulic or pneumatic ram or alternatively a solenoid.

Preferably said actuating means is operated under the control of a control means comprising a switch or suitable sensing means for determining said predetermined circumstances.

Where said actuating means comprises a hydraulic or pneumatic actuator, said control means may comprise a valve for controlling communication between a source of pressurised fluid and said actuating means.

Said switch may be operatively associated with thc fifth wheel of the tractor unit for determining when said movement of the fifth wheel of the tractor unit relative to the trailer exceeds a predetermined angle.

Tn one embodiment said switch may be arranged on the trailer to be operatively located with a V shaped recess in the rear of the fifth wheel of the tractor unit, said switch being actuated by contact with the sides of said V shaped recess when said movement of the fifth wheel of the tractor unit relative to the trailer exceeds said predetermined angle, for example approximately 6° from a straight ahead position.

In one embodiment said actuating means may comprise a hydraulic or pneumatic ram, said control means comprising a hydraulic or pneumatic valve for controlling the supply of pressurised fluid to said hydraulic or pneumatic ram, said valve being mechanically operated in response to operation of said switch.

Tn an alternative embodiment said control means may comprise an electrical switch adapted to control operation of said actuating means.

Said retaining means may also be arranged to maintain said retaining member is its operative position to prevent a steering movement of the at least one pair of steerable rear wheels during reversing of the trailer and/or when the speed of the vehicle exceeds a predetermined speed. In one embodiment said control means of the actuating means may be operatively connected to the reversing light circuit or gear selector of the tractor unit to retain the retaining member in its operative position to lock the at least one pair of steerable rear wheels in said straight ahead position during reversing of the vehicle.

According to a second aspect of the invention there is provided a vehicle having at least one pair of passively steerable rear wheels and incorporating a kickout reduction mechanism according to a first aspect of the invention.

Preferably, the vehicle comprises a drive vehicle and trailer unit assembly, the trailer unit having the at least one pair of the steerable rear wheels.

The term "trailer unit" is intended to embrace semi-trailers.

A kiclcout reduction system in accordance with an embodiment of the present invention will now be described, by way of example only, with reference to Figures 1 and 2 of the accompanying drawings, in which:-Figure 1 is a schematic view of a tractor/trailer having a passively steerable rear wheels incorporating a kickout reduction mechanism according to an embodiment of the present invention; Figure 2a is a plan view of the steerable rear wheels of the trailer of Figure 1 with the kickout reduction mechanism in an operative configuration; Figure 2b is a plan view of the steerable rear wheels of the trailer of Figure 1 with the kiekout reduction mechanism in an inoperative configuration; Figure 3 is a plan view of the fifth wheel ofthe tractor unit; and Figure 4 is a side view of the apparatus of Figure 1.

A typical tractor/trailer combination incorporating passively steerable rear wheels including a kickout reduction mechanism in accordance with an embodiment of the present invention is shown in Figure 1. The trailer unit 2 is pivotally connected to the tractor unit 1 at the junction of the fifth wheel 5 and the trailer kingpin 6, as generally known. The axle 4 of the rearmost pair of wheels of the trailer unit 2 is passively steerable to enable the turning radius of the trailer 2 to closely mimic the turning radius of the tractor unit 1, as is known in the art.

In the absence of the kickout reduction mechanism of the present invention, such arrangement tends to cause the rearmost end of the trailer unit 2 to "kick out during initial steering of the tractor unit into a turn, away from a straight ahead direction due to the steering action of the rear axle 4.

To alleviate this problem, the trailer 2 incorporated a kickout reduction mechanism comprising a pneumatic actuator 10 having a projecting pin 12 defining a retaining member terminating in a roller 14, the pin 12 being moveable between a retracted position (shown in Figure 2b) and an extended position (shown in Figure 2a), said actuator 10 being operable to urge the pin 12 to its extended position, wherein the roller 14 is pushed into engagement with a recess 16 in the steering linkage 18 of the rear axle 4 to lock the steering linkage 18 in a straight ahead position, as shown in Figure 2a, when the actuator 0 is cncrgised.

In the embodiment shown in Figure 1, the supply of pressurised air to the pneumatic actuator 10 is controlled by a valve 20 associated with a switch provided adjacent the fifth wheel 5 of the tractor unit 1, said switch being adapted to activate the valve 20 to divert a supply ofprcssurised fluid from the actuator 10 to release the pin 12 when the switch detects that the steering angle between the trailer and tractor unit excecds a predetermined value, for example around 5° (although the system may be adapted such that the switch activates at any other desired angle).

Tn use, the valve 20 supplies pressurised fluid to the actuator, extending the pin 12 such that the roller 14 engages the recess 16 in the steering linkage 18 to lock the steerable rear axle in the straight ahead position during initial steering of the tractor unit. Once the angle of the trailer with respect to the tractor unit exceeds a predetermined minimum value, such as 6°, the switch is activated to operate the valve 20 to shut off or divert the supply of pressurised fluid from the actuator 10 to release the pin 12 and roller 14, such that the pin can retract to withdraw the roller 14 from the recess 16 in the steering linkage 18, allowing the steerable rear axle 18 to move, permitting the rear wheels to passively steer to follow the curve around which the tractor unit is turning.

In an alternative embodiment, shown in Figures 3 and 4, the valve 20 may be provided on the trailer above the fifth wheel plate 5, the valve having a downwardly projecting actuating member 22 arranged to project into a central region of the V shaped opening 24 in the rear side of the fifth wheel plate 5. During initial steering movement of the tractor unit 1 the trailer 2 is able to rotate about the axis of the trailer king pin 6 to either side of a straight ahead position through an angle of up to around 5° or 6° with the actuator 10 powered and the steering linkage 18 of the steerable rear axle 4 of the trailer 2 locked, before the actuating member 22 of the valve 20 engages the sides of the V shaped opening 24, causing the valve 20 to open and release pneumatic pressure from the pneumatic actuator 10, allowing the pin 12 to retract and the roller 14 move out of the recess 16 in the steering linkage 18, permitting the steering linkage to 18 move, thus allowing the rear wheels to steer as the tractor/trailer unit continues to turn around a corner.

The effect of the kickout reduction mechanism is that it will allow the tractor unit to begin tuming before the rear wheel steering system takes effect, therefore reducing initial kickout.

The invention is not limited to the embodiment(s) described herein but can be amended or modified without departing from the scope of the present invention.

Claims

<claim-text>BClaims 1. A kickout reduction mechanism for least one pair of passively steerable wheels of an articulated vehicle comprising trailer towed by a tractor unit via a fifth wheel assembly on the tractor unit, said mechanism comprising selectively operable retaining means for retaining the at least one pair of passively steerable wheels in a straight ahead position under predetermined circumstances.</claim-text> <claim-text>2. A kickout reduction mechanism as claimed in claim 1, wherein said predetermined circumstances comprise during initial turning of the vehicle from a straight ahead position.</claim-text> <claim-text>3. A mechanism as claimed in claim 2, wherein said retaining means is adapted to retain the at least one pair of passively steerable wheels in a straight ahead position during limited rotary movement of the fifth wheel of the tractor unit with respect to the trailer during initial steering of the tractor unit away from a straight ahead position. r</claim-text> <claim-text>4. A mechanism as claimed in any preceding claim, wherein said retaining means is adapted C to release said least one pair of steerable rear wheels when said rotary movement of the (0 trailer with respect to the fifth wheel of the tractor exceeds a predetermined angle and/or said retaining means is adapted to retain the at least one pair of steerable rear wheels in a straight ahead position during reversing of the articulated vehicle and/or said retaining means is adapted to retain the at least one pair of steerable rear wheels in a straight ahead position when the speed of said articulated vehicle exceeds a predetermined maximum speed above which operation of the passive steering system is undesiraNe.</claim-text> <claim-text>5. A mechanism as claimed in any preceding claim, wherein said retaining means includes a retaining member moveable between an operative position, wherein said retaining member retains the at least one pair of steerable rear wheels in said straight ahead position, and an inoperative position, wherein said at least one pair of steerable wheels are free to be steered.</claim-text> <claim-text>6. A mechanism as claimed in claim 5, wherein said retaining member comprises a projection adapted to engage a recess provided on a moveable part of the rear wheel steering system to lock said rear wheel steering system in a straight ahead position when said retaining member is in its operative position, such that the projection is received within said recess.</claim-text> <claim-text>7. A mechanism as claimed in claim 6, wherein said projection includes a roller to facilitate movement of said projection into and out of said recess.</claim-text> <claim-text>8. A mechanism as claimed in claim 7, wherein said recess comprises a base and sloping side walls extending outwardly from the base to facilitate movement of the roller into and out of the recess.</claim-text> <claim-text>9. A mechanism as claimed in any preceding claim, wherein said retaining member is urged towards its operative position by biasing means, actuating means being provided for selectively urging said retaining member to its operative position to enable steering of the at least one pair of steerable rear wheels.r 10. A mechanism as claimed in any of claims I to 8, wherein said retaining member is urged to, and maintained in, its operative position by actuating means, said actuating means O being operable to maintain said retaining member in said engaged position, said retaining (0 member being free to return to its disengaged position when said actuating means is deactivated.11. A mechanism as claimed in claim 10, wherein biasing means are provided for urging said retaining member towards its inoperative position following deactivation of said actuating means.12. A mechanism as claimed in any of claims 9 to 11, wherein said actuating means comprises a hydraulic or pneumatic ram or alternatively a solenoid.13. A mechanism as claimed in any of claims 9 to 12, wherein said actuating means is operated under the control of a control means comprising a switch or sensing means for determining said predetermined circumstances.14. A mechanism as claimed in claim 13, wherein said control means comprises a hydraulic or pneumatic valve for controlling the supply of pressurised fluid to said actuating means, said valve being mechanically operated in response to operation of said switch or sensing means.15. A mechanism as claimed in claim 13, wherein said control means comprises an electrical switch adapted to control operation of said actuating means.16. A mechanism as claimed in any of claims 13 to 15, wherein said switch or sensing means is operatively associated with the fifth wheel of the tractor unit for determining when said movement of the fifth wheel of the tractor unit relative to the trailer exceeds a predeteimined angle.17. A mechanism as claimed in claim 16, wherein said switch is arranged on the trailer to be operatively located with a V shaped recess in the rear of the fifth wheel of the tractor unit, said switch being actuatcd by contact with the sides of said V shaped recess when said movement of the fifth wheel of the tractor unit relative to the trailer exceeds said 1 predetermined angle. a,0 18. A mechanism as claimed in any ofcaims 13 to 17, wherein said control means of the (0 actuating means is operatively connected to the reversing light circuit or gear selector of the tractor unit to retain the retaining member in its operative position to lock the at least one pair of steerable rear wheels in said straight ahead position during reversing of the vehicle.19. A vehicle having at least one pair of passively steerable rear wheels and incorporating a kickout reduction mechanism as claimed in any of claims ito 18.20. A vehicle as claimed in claim 19 comprising a drive vehicle and trailer unit assembly, the trailer unit having the at least one pair of the steerable rear wheels.21. A kickout reduction mechanism substantially as herein described with reference to the accompanying drawings.</claim-text>