AU2019250280A1 - Improvements in Trailers and Combination Vehicles - Google Patents

Abstract

Abstract A trailer for use in a combination vehicle for road transport of heavy goods. The trailer comprises a semi-trailer body adapted to carry the goods and which includes a 5 trailing axle set at its rear. The trailer also includes a dog trailer mounted beneath the front of said semi-trailer body. The dog trailer comprises: - a first frame portion connected to the semi-trailer body by a first pivoting connection and carrying a rear axle set, - a second frame portion connected to the first frame portion by a second 10 pivoting connection and carrying a front axle set, and - a drawbar assembly attached to the second frame portion by a third pivoting connection.

Description

Improvements in Trailers and Combination Vehicles

Field of the Invention

This invention concerns goods-carrying road vehicles. It is particularly concerned with such vehicles having a rigid truck or a prime mover towing a trailer or a set of trailers.

Background to the Invention

Articulated road vehicles come in many different forms and sizes. In general, the longer the vehicle is, and the more wheels it has, the greater the load it can carry. However road authorities regulate the load upon, and spacing of, axles to control the loads placed on roads, and particularly bridges, so heavier and larger and longer 15 vehicles are restricted in their access to certain roadways. However with increased length comes the disadvantage of reduced low-speed manoeuvrability which is required for travelling on existing roads, through intersections and turning in restricted spaces. To increase low-speed manoeuvrability for a given length of vehicle, the number of articulation points can be: increased. But this generally 20 reduces the high-speed stability/manoeuvrability of the vehicle as does shortening the length of the vehicle. There has historically thus been a trade-off between low-speed manoeuvrability (swept path) and high-speed stability/manoeuvrability.

The present invention provides an improvement in that trade-off for the types of 25 vehicles concerned.

In this specification, the following explanations apply to certain terms. The terms are believed to be understood by one of ordinary skill in the art, but the explanations are provided for reference if clarification is required.

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a) A “heavy goods combination vehicle” (sometimes abbreviated to “combination vehicle”) is a heavy goods or road transport vehicle with at least one articulation point.

b) A “semi-trailer” is a towed vehicle unit of a heavy goods combination vehicle whose means of attachment to the preceding vehicle unit (a prime mover, another semi-trailer, or a converter dolly) results in some of its vertical load being imposed on said preceding unit flirough a tow coupling and whose rear is supported by a single axle or multiple axle set (tandem, tri or quad axle 10 set) located towards the rear.

c) An “axle set” or “axle group” is either:

- a group of axles, including their road wheels, beneath a vehicle unit in sufficiently close proximity to each other that their interactions with the pavement beneath are considered to overlap, or

- a single axle including its road wheels mounted beneath a vehicle unit, or

- as defined in the prevailing transport regulations and/or design rules.

A tandem axle set has two axles in close proximity, a tri-axle set has three 20 axles in close proximity, and a quad axle set has four axles in close proximity.

The axle sets described in this specification can have two or four wheels on each axle so, for example, a tandem axle group can have either four or eight wheels.

d) A “converter dolly” (also called a “dolly” or “forecarriage” or “pig trailer”) is a towed vehicle unit of a heavy goods combination vehicle whose tow coupling to the preceding vehicle unit (a rigid truck, a prime mover or a semitrailer) results in little or none of its vertical load being imposed on said preceding vehicle unit through the tow coupling (see below) and whose rear is 30 supported by a single axle or a tandem or tri-axle set located at or near to the centre of the main load carrying area. The main load bearing or carrying area of a converter dolly usually incorporates a tow coupling device (a quick release fifth wheel coupling, ballrace turntable, or non-separable turntable) so that the dolly may be mounted beneath the front of a semi-trailer body, thereby converting the semi-trailer into a “trailer”. In some countries a converter dolly is also known as a pivoting bogie, a dolly truck or a special truck.

e) A “trailer” in a heavy goods combination vehicle is a towed vehicle unit that can be either a pig trailer, a semi-trailer, or a combination of a converter dolly plus semi-trailer.

f) A “set of trailers” is two or more trailers connected to be towed one behind the other.

g) In a heavy goods combination vehicle, a “truck” or “rigid truck” is a rigid motor vehicle constructed primarily for the carriage of goods and having at least two axles, four wheels and a gross laden mass of at least 12 tonnes.

h) A “dog trailer” is a trailer with two axle groups of which the front axle group is steered by connection to the preceding vehicle unit by way of a drawbar assembly.

i) A “pig trailer” is a trailer having one axle group near the middle of the length of the goods or load carrying surface.

j) A “prime mover” is a motor vehicle unit of a heavy goods combination vehicle built to tow a semi-trailer, a converter dolly or a trailer.

k) A “vehicle unit” is either a trailer, a semi-trailer, a converter dolly, or a motor vehicle. Thus a combination vehicle has a plurality of such vehicle units connected by an articulated coupling between each adjacent vehicle unit.

1) A “coupling” or “coupling assembly” is a mechanical assembly which provides connection between one vehicle unit (the leading vehicle unit) and

2019250280 18 Oct 2019 another vehicle unit (the trailing vehicle unit) immediately behind. Typically a first portion of the coupling is affixed to the leading vehicle unit, a second portion of the coupling is affixed to the trailing vehicle unit and the first and second portions are releasably or permanently connected.

m) A “fifth wheel coupling” or “fifth wheel assembly” provides a connection and means of articulation between a semi-trailer and the vehicle unit immediately ahead (the towing unit). Typically, the coupling comprises a kingpin and skid plate on the underside of the front of the semi-trailer, and a horseshoe-shaped component called a fifth wheel or coupler plate on the rear of the towing unit. These two components when coupled are locked together using a quick release mechanism. When coupled, the kingpin is free to rotate in the fifth wheel about an axis that is largely vertical and normal to the plane of the goods carrying surface so providing articulation between the linked 15 vehicle units. The fifth wheel can tilt fore and aft on a horizontal pin (about a transverse axis) thus providing for vertical angulation between linked vehicle units. The fifth wheel is not free to tilt sideways thereby roll coupling the linked vehicle units. In practice there is some freeplay (or lash) in the connection allowing some sideways tilt under heavy sideways loads and 20 usually evident only when the vehicle is close to rollover.

n) A “ballrace turntable” is a type of coupling used to provide articulation between a semi-trailer and the vehicle unit immediately ahead. In contrast to a fifth wheel coupling it essentially provides no vertical or sideways tilt between the vehicle units thereby attached. Ballrace turntables are sometimes fitted with a mechanical locking device to selectively prevent articulation. The device, when fitted, is typically engaged to assist the driver when reversing the vehicle.

o) A “drawbar assembly” is the portion of a dolly that connects the dolly’s frame or chassis to the vehicle unit in front for towing purposes.

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p) A “ringfeder” is a generic name (previously a trademark) commonly used worldwide to identify a type of automatic bolt coupling device (pin-type hitch/coupling) utilizing a swivelable cast bell portion with a horizontal opening and a machined pin which connects to a towing eye located on the 5 front of a drawbar assembly. The connection between the towing eye and the pin is a “rotationally free joint” equivalent to a ball joint. The hitch point of a ringfeder coupling is at the longitudinal axis of the pin which engages with the towing eye located at the front of the drawbar.

q) The “Gross Combination Mass” (or GCM) of a combination vehicle is a value specified by the manufacturer as being the maximum of the sum of the maximum laden mass of the prime mover plus the sum of the Axle Loads of all other vehicle units in the combination vehicle.

r) A “B-double” is a multi-articulated goods carrying vehicle comprising a rear semi-trailer attached directly to a front semi-trailer, usually through a fifth wheel coupling, and which is, in turn, attached directly to a prime mover, also usually through a fifth wheel coupling.

s) An “A-double” is a multi-articulated goods carrying vehicle comprising a rear dog-trailer attached directly to a front semi-trailer, usually through a ringfeder coupling, which is, in turn, attached directly to a prime mover usually through a fifth wheel or turntable coupling.

t) A “tow coupling overhang” refers to the distance that a hitch point is located rearwards of the relevant axle centre or axle group centre. If the hitch point is located forwards of the relevant axle centre or axle group centre, then it can be considered as a negative tow coupling overhang.

Summary of the Invention

In one aspect, the invention provides a combination vehicle for road transport of heavy goods, said vehicle comprising:

A trailer for use in a combination vehicle for road transport of heavy goods, said trailer comprising:

- a semi-trailer body adapted to carry said goods and including a trailing axle set at its rear, and

- a dog trailer mounted beneath the front of said semi-trailer body, said dog trailer comprising

- a first frame portion connected to said semi-trailer body by a first pivoting connection and carrying a rear axle set,

- a second frame portion connected to said first frame portion by a second pivoting connection and carrying a front axle set, and

- a drawbar assembly attached to said second frame portion by a third pivoting connection.

Preferably said dog trailer has a first axle set and a second axle set spaced sufficiently apart for them to be treated under transport regulations as separate axle sets.

The dog trailer may have two axle groups of which the front axle group is steered by connection to the preceding vehicle unit by way of said drawbar assembly.

Said first pivoting connection may be a fifth wheel coupling or a turntable which may be a non-separable turntable or a quick release turntable.

Preferably said second pivoting connection is a ballrace turntable.

Preferably said drawbar assembly pivots up and down from said second frame portion.

Preferably said drawbar assembly has a ringfeder coupling portion at its front end.

Preferably said rear axle set has at least one self-steer axle lockable in the straightahead position. In some preferred embodiments said rear axle set is a single axle.

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In some preferred embodiments said second pivoting connection is a lockable turntable.

In another aspect, the invention provides a combination vehicle for road transport of 5 heavy goods, said vehicle comprising:

- a motor vehicle at the front, and

- a trailer attached to said motor vehicle so els to be towed behind the motor vehicle, said trailer comprising:

- a semi-trailer body adapted to carry at least some of said goods,

- a trailing axle set supporting the rear of the semi-trailer body, and

- a dog trailer mounted beneath the front of said semi-trailer body, said dog trailer comprising:

- a first frame portion connected to said semi-trailer body by a first pivoting connection and carrying a rear axle set,

- a second frame portion connected to said first frame portion by a second pivoting connection and carrying a front axle set, and

- a drawbar assembly whose rear end is attached to said second frame portion by a third pivoting connection and which is coupled at its front end to the rear of said motor vehicle.

In some preferred embodiments said motor vehicle is a rigid truck.

Said rear axle set may be a self-steering single axle.

Said combination vehicle may comprise means for locking said second pivoting connection in the straight-ahead position at low road speeds and means for locking said self-steering axle on the dog trailer in the straight-ahead position at high road speeds.

In those embodiments the distance from the front axle of the motor vehicle to the rear axle of said trailer is preferably not less than 17 metres.

Said trailing axle set may be a tandem axle set the rearmost axle of which is a selfsteer axle.

The rearmost axle in said trailing axle set may be a self-steer axle and the vehicle includes means to lock said rearmost self-steer axle in the straight ahead position at high speeds.

In those embodiments the distance from the front axle of the motor vehicle to the rear axle of said trailer is preferably not less than 18.333 metres.

In a further aspect, the invention provides a method of operating a combination vehicle for road transport of heavy goods, said vehicle comprising:

- a motor vehicle at the front, and

- a trailer attached to said motor vehicle so as to be towed behind the motor vehicle, said trailer comprising:

- a semi-trailer body adapted to carry at least some of said goods,

- a trailing axle set supporting the rear of the semi-trailer body, and

- a dog trailer mounted beneath the front of said semi-trailer body, said dog trailer comprising:

- a first frame portion connected to said semi-trailer body by a first pivoting connection and carrying a rear axle set,

- a second frame portion connected to said first frame portion by a second pivoting connection and carrying a front axle set, and

- a drawbar assembly whose rear end is attached to said second frame portion by a third pivoting connection and whose front end is coupled the rear of said motor vehicle;

said method comprising selectively locking and unlocking the pivotal action of said first and second pivoting connections in response to preset ranges of road speeds during forward motion of the vehicle.

In said method:

- said second pivoting connection may be a lockable turntable, and

- said rear axle set may be a self-steer rear axle:, and said method preferably comprises:

at selected high road speeds, unlocking said lockable turntable forming the second pivoting connection so it is free to rotate as induced by the motion of the vehicle, and locking said self-steer rear axle into the straight-ahead position, and at selected low road speeds, locking said turntable forming the second pivoting connection into its straight-ahead position and unlocking said selfsteer rear axle so it is free to steer as induced by the motion of the vehicle.

Preferably:

- said trailing axle set is a tandem axle set the rearmost axle of which is a selfsteer axle, and said method comprises:

- at said high road speeds, locking said rearmost axle into the straight-ahead position, and

- at said low road speeds, unlocking said rearmost axle so it is free to steer as induced by the motion of the vehicle.

Said motor vehicle may comprise a leading semi-trailer the rearmost axle of which is a self-steer axle, and said method may comprise:

- at said high speeds, locking said leading semi-trailer’s rearmost self-steer axle into the straight-ahead position; and at said low speeds unlocking said leading semi-trailer’s rearmost self-steer axle so it is free to steer as induced by the motion of the vehicle.

Alternatively in said method:

- said first pivoting connection is a first lockable turntable,

- said second pivoting connection is a second lockable turntable, and said rear axle set is a self-steer axle, and said method includes:

- at a selected range of high road speed conditions unlocking said first and second lockable turntables so they are free to rotate as induced by the motion of the vehicle, and

- locking said self-steer rear axle into the straight-ahead position.

Alternatively in said method:

- said first pivoting connection is a first lockable turntable,

- said second pivoting connection is a second lockable turntable, and said rear axle set is a self-steer axle, and said method includes:

- at a selected range of high road speed conditions, locking said first lockable turntable into the straight-ahead position,

- and unlocking the self-steer axle so it is free to steer as induced by the motion of the vehicle.

Alternatively in said method:

- said first pivoting connection is a first lockable turntable,

- said second pivoting connection is a second lockable turntable, and said rear axle set is a lockable self-steer axle, and said method includes at a selected range of high road speed conditions:

- , unlocking said first lockable turntable so it is free to rotate as induced by the motion of the vehicle, and

- locking said self-steer rear axle into the straight-ahead position.

Brief Description of the Drawings

In order that the invention may be more fully understood there will now be described, by way of example only, preferred embodiments and other elements of the invention with reference to the accompanying drawings where:

Figure 1 is a view of a preferred trailer according to a first embodiment of the present invention;

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Figure 2 is part exploded view of the trailer shown in Figure 1 separated into dog trailer and semi-trailer portions;

Figure 3 is a further exploded view of the dog trailer portion shown in Figure 2;

Figures 4A to 4G show additional trailers which are alternative embodiments of 5 the invention;

Figures 5A to 5C show successively exploded views of the trailer shown in Figure 4B;

Figures 6A to 6C show successively exploded views of the trailer shown in Figure 4C;

Figures 7A to 7E show truck-plus-trailer combination vehicles according to further embodiments of the invention which incorporate various trailers shown in Figures 4A to 4G, and with the illustrations annotated to indicate the allowable loads at each axle set;

Figure 8 is an enlarged view of the vehicle shown in Figure 7A which is one 15 preferred embodiment of the invention;

Figure 9 is an enlarged view of the vehicle shown in Figure 7B which is another preferred embodiment of the invention;

Figure 10 is a visual key to the relationship between vehicles shown in Figures lOAto 10M;

Figures 10A to 10G show a comparison of the load carrying capacities of a selection of existing A-double combinations (Figures 10A, 10B and 10C), when compared to alternative vehicles (Figures 10D, 10E, 10F and 10G) according to additional embodiments of the present invention, and showing below each axle set the load carrying capacity of that axle set;

Figures 10H to 10M show some additional configurations according to further embodiments of the invention, together with the load carrying capacities at each axle set;

Figure 11 shows a particularly preferred combination vehicle according to a further embodiment of the invention, when compared with a version of the 30 invention substantially the same as that shown in Figure 8, showing the preferred state of the lockable turntable and lockable self-steer axle at high and low road speeds;

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Figure 12 shows a further particularly preferred combination vehicle according to a further embodiment of the invention when compared with a version of the invention substantially the same as that shown in Figure 9, showing the preferred state of its lockable turntable and lockable self-steer axles at high and 5 low road speeds;

Figure 13 shows another particularly preferred combination vehicle according to a further embodiment of the invention being compared with a version of the invention substantially the same as that shown in Figure 10D, showing the preferred state of its lockable turntable and lockable self-steer axles at high and 10 low road speeds;

Figures 14, 15 and 16 show three different operating modes of another trailer according to a further embodiment of the invention;

Figure 17 is another view of the trailer in Figures 14 to 16 and is shown for ease of comparison with the trailers in Figures 18 and 19; and

Figures 18 and 19 show two other trailers according to further embodiments of the invention.

The drawings are schematics only and are not necessarily all to the same scale. Where an axle is shown with a X across a wheel, it indicates that is a self-steering 20 axle.

With respect to the different embodiments of the invention, features which have equivalent function in each embodiment are identified by numerals which are one hundred different from the numerals identifying equivalent features in the other 25 embodiments.

Discussion of Embodiments of the Invention

In regard to the trailer embodiment shown in Figures 1 to 3, and the use of that trailer 30 in the combination vehicle embodiment shown in Figure 8, the trailer 100 is constructed for use in a combination vehicle 130 for road transport of heavy goods. The trailer 100 is shown carrying goods 104. The trailer 100 comprises a semi-trailer body 102, including a goods carrying area 101, and having a single axle 103 complete

2019250280 18 Oct 2019 with road wheels 126, at the rear of the trailer forming a trailing axle set 105. A dog trailer 106, that does not have a goods carrying area, is mounted beneath the front 108 of the body 102.

The dog trailer 106 comprises a first frame portion 110 and a second frame portion 114. The first frame portion is connected to the semi-trailer body 102 by a coupling 112, which is shown as a quick release fifth-wheel coupling in Figures 1-3 and 8. A non-separable turntable coupling may be used as an alternative. The coupling 112 functions as a pivoting connection between the semi-trailer body and the first frame 10 portion 110 and roll-couples the semi-trailer body 102 and the dog trailer 106. That means the semi-trailer body 102 and the first frame portion 110 will rollover together through turntable coupling 112. The roll-coupled connection between semi-trailer body 102 and trailer 106 is commonly referred to as a “B-type” connection.

The coupling 112 allows steering rotation of the dog trailer 106 about a vertical axis through the coupling. The coupling also allows the dog trailer to pivot through a limited range (about plus or minus 20°) about a transverse axis relative to the semitrailer body 102 thereby ensuring sharing of loads between the trailer’s front axle 124 and rear axle 122.

The second frame portion 114 is connected to the first frame portion 110 by a ballrace turntable 116 which forms a second pivoting connection, this time between the first frame portion 110 and the second frame portion 114. A single rear axle 122, complete with road wheels 126, extends across the rear of the first frame portion 110 25 to form a rear axle set 123 for trailer 106. A front axle 124, complete with road wheels 126, extends across the second frame portion 114 to form a front axle set 125 for the trailer 106. This creates a single axle dolly at the front of the trailer 106.

The rear end 120 of a drawbar 118 is pivotally attached to the front 119 of the second 30 frame portion 114 so as to form a third pivotal connection 121 on the trailer 100. The trailer 106 can therefore be considered as having a dog trailer configuration.

As shown in Figure 3, the first frame portion 110 of trailer 106 is a semi-trailer chassis, which does not have a goods carrying area but instead has a turntable in the form of a fifth wheel connector to support a load, while the second frame portion 114 in conjunction with the drawbar 118 forms a single-axle dolly (or pig trailer/truck/forecarriage) 127 coupled to the first frame portion 110 through the ballrace turntable 116.

As shown in Figure 8, the front end of the drawbar 118 comprises a coupling portion 129 which mates with a corresponding coupling portion 131 on a towing vehicle 128. In use the drawbar 118 attaches to a motor vehicle, which is a rigid truck 128 in Figure 8, and which provides propulsion for the combination vehicle 130. The attachment is via a ringfeder pin or ball-type coupling, pintle hitch, or equivalent at the front of the drawbar 118. There is no roll-coupling through coupling portion 129 between the trailer 100 and truck 128, and therefore the trailer 100 and truck 128 can each rollover independently of the other. Where there is no roll-coupling through a coupling assembly, the connection is commonly referred to as an “A-type” connection.

The trailer 100 described above, comprising a two axle dog trailer 106 coupled through an A-type connection to the towing vehicle 128 and coupled through a B-type connection 116 to a towed goods carrying semi-trailer 102 is described, generically hereinafter, as an “AB trailer”. This is because the trailer 106 has an Atype coupling to the towing vehicle and has a B-type coupling to the goods carrying semi-trailer.

The combination vehicle 230 shown in Figure 9 comprises a truck 228 the same as that in Figure 8 plus a trailer 200 having a two axle lead (dog) trailer 206 the same as that in Figure 8. However the trailing axle set 205 of the trailer 200 is a tandem axle set in order to provide a greater GCM.

As can be seen from Figures 4B, 5A, 5B and 5C, the trailer 300 shown in Figure 4B shares many characteristics in common with the trailer 200 shown in Figures 4A and 9. The trailer 300 comprises a semi-trailer body 302, having a tandem axle set 305 forming a trailing axle set, plus a trailer 306 mounted beneath the front 308 of the body 302. The trailer 306 comprises a first frame portion 310 and a second frame portion 314. The first frame portion is connected to the semi-trailer body 302 by a quick release fifth wheel turntable or a non-separable turntable coupling 312 which forms a B-type coupling between the semi-trailer body 302 and the first frame portion 310 of the trailer, and which functions as a pivoting connection between the semitrailer body 302 and the first frame portion 310.

The second frame portion 314 is connected to the first frame portion 310 by a ballrace turntable 316 which forms a second pivoting connection, this time between the first frame portion 310 and the second frame portion 314.

A drawbar 318 is pivotally attached at its rear end 320 so as to form a third pivotal connection on the trailer 300. As in other embodiments described above, the trailer 306 can therefore be considered as a dog trailer configuration.

A tandem axle set 322 extends across the rear of the: first frame portion 110. A front axle set 324 extends across the second frame portion.

The trailer 300 therefore has the form of a 5-axle AB-trailer.

As can be seen from Figures 4C, 6A, 6B, and 6C, the trailer 400 shown therein shares many features with the previously described trailer 300. The most significant difference is that in the tandem axle set 403 on the semi-trailer body, and in the tandem axle set 422 on the dog trailer 406, the respective back axles 432 and 434 are self-steering axles. The trailer 400 is therefore a 5-axle AB-trailer with two self-steer axles.

In all the embodiments shown in Figures 7A to 7E, the truck 128 is the same. Under current Australian legislation it has a maximum allowable load of up to 6.5 tonnes on the front axle and a maximum allowable load of up to 17 tonnes on the rear tandem axle set.

In each of Figures 7A to 7E the allowable load for each axle set in the vehicles is shown below the respective axle set. The minimum lengths (front axle to trailing axle) for each configuration in some jurisdictions in Australia are:

Fig 7A truck and 3-axle AB-trailer min length 1700 mm

Fig 7B truck and 4-axle AB-trailer min length 18333 mm

Fig 7C truck and 5-axle AB-trailer min length 23333 mm

Fig 7D truck and 6-axle AB-trailer min length 25667 mm

Fig 7E truck and 5-axle AB-trailer with self-steer axles min length 23333 mm

Although the actual allowable loads and the minimum lengths may vary from jurisdiction to jurisdiction, the loads and dimensions stated are generally indicative.

The embodiment in Figure 7C has the first frame portion 310 extended when compared to the corresponding component 110 in Figures 7A and 7B. The front axle on the trailer 306 comprises a single axle set. The rear axle set 323 on the trailer 306 is a tandem axle set at the rear of the frame portion 310. The tandem axle set and the single axle set are spaced sufficiently apart that they are treated as individual axle groups for the purposes of calculating allowable loads.

The trailer 400 shown in Figure 7E is similar overall to the configuration of the trailer 300 in Figure 7C. Both are 5-axle AB-trailers. But, the rearmost axle 434 on the dog trailer 406 is a self-steer axle, which aids reduction of the swept path width during low speed turns. The trailer 400 also has a self-steering axle 432 at the rear of the semi-trailer, which similarly helps to reduce off-tracking in low-speed turns. Where self-steer axles are used in the manner described it is often preferable to lock them on-centre (zero steer angle) when travelling at high speed to improve high-speed stability and manoeuvrability.

The trailer 500 in Figure 7D has a triaxle set at its rear, to increase its allowable load, but is otherwise the same as the trailer 300. It is a 6-axle AB-trailer.

Figures 4C to 4G illustrate larger capacity versions of trailers according to the invention and, in the case of 4E, how the function of the trailer may be divided between two trailers, forming a B-double semi-trailer pair, in order to carry an even greater load.

The combination vehicles shown in Figures 10A to 10G are of even larger capacity. The vehicles in Figures 10A, 10B and 10C are all of an A-double configuration, already known to industry and those skilled in the art. The vehicles in Figures 10D, 10E, 10F, and 10G are all in accordance with different embodiments of the present invention and the AB-trailer concept. As can be seen from the visual key Figure 10, the vehicles in Figures 10A, 10B and 10C correspond to Figures 10D, 10E, and 10G respectively which have an AB-trailer. The load carrying capacities shown in the Figures are based on current maximum axle group load limits as indicated when approved to operate on some roadways in Victoria, Australia.

The lead dog-trailer in each AB-trailer always has two axle sets and a main chassis that supports a turntable free to pivot about a transverse axis. The front axle set on the dog trailer typically has a single axle but it may also be a tandem axle set. The rear axle set on the dog trailer may be a single axle, a tandem axle set or a tri-axle axle set.

All of the trailers 100, 200, 300, 400, 500, 600, 700, and 800, can be considered to be AB-trailers. As noted before, this is because the drawbar has an A-type coupling to the towing vehicle and has a B-type coupling to the goods carrying semi-trailer or trailers.

The combination vehicle 530 shown in the lower portion of Figure 11 has for its motor vehicle the same rigid truck 128 as in combination vehicle 130. The trailer 500 in vehicle 530 has substantially the same configuration as the trailer 100 in Figure 1 except for two significant features. The ballrace turntable 516 is lockable in the straight-ahead position whereas turntable 116 has no such locking feature. Also the rear axle 522 on the dog trailer 506 is a lockable self-steer axle whereas the corresponding axle 122 is not a self-steer configuration. When operating the combination vehicle 530 incorporating the trailer 500, at low road speed:

- the ballrace turntable 516 is locked in the straight-ahead position, and

- the self-steer axle 522 is unlocked, while at high road speed:

- the turntable 516 is unlocked, and

- the self-steer axle 522 is locked.

The term “low speed” when used above refers to that speed below which vehicle stability and dynamic effects are no longer a safety issue under typical in-service operation. That speed is usually somewhere in the range 30 to 60 km/hr. The term “high speed” means above about 30 to 60 km/hr.

By incorporating the lockable turntable 516 and self-steer axle 522 into the trailer 500, the low speed swept path of the trailer and offtracking is advantageously reduced and its high speed performance is improved, so making the combination vehicle more stable and its tracking improved.

The combination vehicle 630 shown in the lower portion of Figure 12 has the same rigid truck 228 as in combination vehicle 230. The trailer 600 in vehicle 630 is mostly the same as the trailer 200 shown in Figure 9 except that its dog trailer component 606 has the same modifications as described above for trailer 500. In particular the ballrace turntable 616 is lockable in the straight-ahead position, and the rear axle 622 is a lockable self-steer axle. In addition, the back axle 632 in the trailing axle set 603 is also lockable. When operating the combination vehicle 630 incorporating the trailer 600, the turntable 616 and self-steer axles 622 and 632 are locked and unlocked according to speed as indicated, by the annotations at the bottom of Figure 12.

The combination vehicle 730 shown in the lower portion of Figure 13 has for its motor vehicle 728 a combination vehicle comprising a prime mover 738 and semi-trailer 740. The trailer 700 in vehicle 730 has the same configuration as the trailer 600 shown in Figure 12. The rear axle 732 on the trailing tandem axle set 705 is a lockable self-steer axle which in use is controlled in the same manner as the self-steer axle 722 on the dog trailer 706. The leading semi-trailer 740 forming part of the motor vehicle 730 also has a tandem axle set 742 the rear axle of which is a self-steer axle 744.

When operating the combination vehicle 730 incorporating the trailer 700, at low road speed (such as below about 30 km/hr):

the ballrace turntable 716 is locked in the straight-ahead position, and

- the self-steer axles 722, 732 and 744 are unlocked, while at high speed (above about 30 km/hr):

- the turntable 716 is unlocked, and the self-steer axles 722, 732 and 744 are locked in the straight-ahead position.

This provides even greater improvements in low-speed performance when compared with the trailer 300.

Switching between the low speed and high speed locking conditions can be controlled automatically from the motor vehicle or from a microcontroller mounted on the trailer.

The trailer 800 shown in Figures 14, 15 and 16 is the same as the trailer 100 in Figure 1 except that the turntables 812 and 816 are both lockable in the straight-ahead position, and the rear axle 822 on the dog trailer 806 is a self-steering axle which is lockable in the straight-ahead position. In use, actuation controls operating from the motor vehicle (or on-board micro-controller) automatically activate and deactivate the locks on the self-steering axle 822, and the turntables 812 and 816 such that:

- as indicated in Figure 14, at high-speed in one operating mode the first and second lockable turntables are unlocked, and thus free to rotate (articulate), and the self-steer rear axle 822 is locked into its straight-ahead position;

as indicated in Figure 15, at high-speed in another operating mode, the first turntable 812 is locked while the second turntable 816 is unlocked and the axle 822 is unlocked;

- as indicated in Figure 16, at high-speed in a further operating mode, the first turntable 812 is unlocked, the second turntable 816 is locked, and the rear self-steering axle 822 is locked.

Locking and unlocking the turntable 812, and the self-steer axles 822 as described for Figures 14, 15, and 16 allows the effective wheelbases of the component vehicle units to be beneficially varied as desired while on the move. Each of the three high-speed operating modes has particular characteristics and the one that is selected will depend on the stability characteristics of the combination vehicle.

The effective wheelbases for the embodiments shown in Figures 14 to 16 are indicated by the distances marked WB1, WB2, and WB3. In Figure 14, the distance WB1 is the wheelbase for the dog trailer’s dolly 827 (effectively the drawbar length), the distance WB2 is the dog trailer’s wheelbase portion, and WB3 is the wheelbase of the goods carrying semi-trailer 802.

In Figure 15, where the first turntable 812 is locked, the length of wheelbase WB3 is increased. The longer wheelbases provide additional stability for the trailer at high road speeds.

In regard to the trailer configuration shown in Figure 16, when at high road speed, both the second turntable 816 and the self-steer axle 822 are locked while the first turntable 812 is unlocked. The dog trailer 806 then becomes a dolly (or pig trailer) with a long drawbar 818 and a wide spread of axles in the tandem. There is an increase in the effective wheelbase WB1.

Included in Figures 17 to 19 are annotations showing the locked/unlocked status of the respective self-steer axles and lockable turntables for both low-speed and highspeed optional operating modes of the respective trailers.

The trailer 800 shown in Figure 17 has the same construction as trailer 800 shown in Figures 14, 15 and 16. But the tabulated annotations included in Figure 17 give details for six different locking statuses for the combination of the second turntable (column 2), first turntable (column 3), and rear axle (column 4). The table in Figure 17 includes the locking statuses for Figure 14 at line 1, for Figure 15 at line 2, and for Figure 16 at line 3, these all being for different configurations when operating at high road speeds. The table in Figure 17 also shows, at lines 4, 5 and 6, the locking statuses for three different configurations when operating at low road speeds and which affect offtracking in a turn, low-speed turn and swept path width.

For most requirements it is likely that only a single configuration of locking statuses would be used at high speed, and a single configuration of locking statuses used at low speed for a given trailer in a given combination vehicle.

But the same trailer in a different combination vehicle, or perhaps undergoing a different duty in the same combination vehicle, may be operated with an alternative configuration of locking statuses.

Alternatively, for more sophisticated requirements, the trailer may be operated with two or more of the high speed locking configurations being invoked sequentially as travelling conditions change. Similarly, two or more of the low speed locking configurations may be invoked sequentially as low speed travelling conditions change.

The trailer 900 in Figure 18 is substantially the same as trailer 200 in Figure 9 except that for the trailer in Figure 18 the rear axle 922 on the dog trailer is a lockable self-steering axle, and the first and second turntables are each lockable in the straight-ahead position.

The tabulation included as portion of Figure 18 shows, in a similar manner to Figure 17, details of 6 different statuses for the combination of the second turntable 916, first turntable 912 and rear axle 922 for the trailer 900.

The trailer 1000 in Figure 19 is the same as the trailer 900 in Figure 18 except that the last axle 1032 in trailer 1000’s trailing axle set 1005 is a self-steer axle which is lockable by control from the motor vehicle or on-board microcontroller. When operating at low road speed the rearmost self-steer axle is preferably always unlocked to reduce offtracking and swept path width in a turn.

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The tabulation included as portion of Figure 19 shows in a similar manner to Figure 17, details of 6 different locking statuses for the combination of the second turntable 1016, first turntable 1012 and rear axle 1022 and trailing axle 1003 for the trailer 1000.

While the above description includes the preferred embodiments of the invention, it is to be understood that many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention.

It will be also understood that where the word “comprise”, and variations such as “comprises” and “comprising”, are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge of persons skilled in the art.

Claims (26)

1. Claims

   1. A trailer for use in a combination vehicle for road transport of heavy goods, said trailer comprising:

   - a semi-trailer body adapted to carry said goods and including a trailing axle set at its rear, and

   - a dog trailer mounted beneath the front of said semi-trailer body, said dog trailer comprising:

   - a first frame portion connected to said semi-trailer body by a first pivoting connection and carrying a rear axle set,

   - a second frame portion connected to said first frame portion by a second pivoting connection and carrying a front axle set, and

   - a drawbar assembly attached to said second frame portion by a third pivoting connection.
2. 2. A trailer according to claim 1 wherein said dog trailer has two axle groups of which the front axle group is steered by connection to the preceding vehicle unit by way of said drawbar assembly.
3. 3. A trailer according to claim 1 or 2 wherein said first pivoting connection is a quick release turntable.
4. 4. A trailer according to claim 1 or 2 wherein said first pivoting connection is a non-separable turntable.
5. 5. A trailer according to claim 1 or 2 wherein said first pivoting connection is a fifth wheel coupling.
6. 6. A trailer according to any one of the previous claims wherein said second pivoting connecting is a ballrace turntable.
7. 7. A trailer according to any one of the previous claims wherein said drawbar assembly pivots up and down from said second frame portion.
8. 8. A trailer according to any one of the previous claims wherein said drawbar assembly has a ringfeder coupling portion at its front end.
9. 9. A trailer according to any one of the previous claims wherein said rear axle set has at least one self-steer axle lockable in the straight-ahead position.
10. 10. A trailer according to any one of the previous claims wherein said rear axle set is a single axle.
11. 11. A trailer according to any one of the previous claims wherein said second pivoting connection is a lockable turntable.
12. 12. A combination vehicle for road transport of heavy goods, said vehicle comprising:

    - a motor vehicle at the front, and

    - a trailer attached to said motor vehicle so as to be towed behind the motor vehicle, said trailer comprising:

    - a semi-trailer body adapted to carry at least some of said goods,

    - a trailing axle set supporting the rear of the semi-trailer body, and

    - a dog trailer mounted beneath the front of said semi-trailer body, said dog trailer comprising:

    - a first frame portion connected to said semi-trailer body by a first pivoting connection and carrying a rear axle set,

    - a second frame portion connected to said first frame portion by a second pivoting connection and carrying a front axle set, and

    - a drawbar assembly whose rear end is attached to said second frame portion by a third pivoting connection and which is coupled at its front end to the rear of said motor vehicle.
13. 13. A combination vehicle according to claim 12 wherein said motor vehicle is a rigid truck.
14. 14. A combination vehicle according to claim 12 or 13 wherein said rear axle set is a self-steering single axle.
15. 15. A combination vehicle according to claim 12 comprising means for locking said second pivoting connection in the straight-ahead position at low road speeds and means for locking said self-steering axle on the dog trailer in the straight-ahead position at high road speeds.
16. 16. A combination vehicle according to claim 15 in which the distance from the front axle of the motor vehicle to the rear axle of said trailer is not less than 17 metres.
17. 17. A combination vehicle according to any one of claims 12 to 16 wherein said trailing axle set is a tandem axle set the rearmost axle of which is a self-steer axle.
18. 18. A combination vehicle according to claim 17 wherein the rearmost axle in said trailing axle set is a self-steer axle and said vehicle includes means to lock said rearmost self-steer axle in the straight ahead position, at high speeds.
19. 19. A combination vehicle according to claim 17 or 18 in which the distance from the front axle of the motor vehicle to the rear axle of said trailer is not less than 18.333 metres.
20. 20. A method of operating a combination vehicle for road transport of heavy goods, said vehicle comprising:

    - a motor vehicle at the front, and

    - a trailer attached to said motor vehicle so as to be towed behind the motor vehicle, said trailer comprising:

    - a semi-trailer body adapted to carry at least some of said goods,

    - a trailing axle set supporting the rear of the semi-trailer body, and

    - a dog trailer mounted beneath the front of said semi-trailer body, said dog trailer comprising:

    - a first frame portion connected to said semi-trailer body by a first pivoting connection and carrying a rear axle set,

    - a second frame portion connected to said first frame portion by a second pivoting connection and carrying a front axle set, and

    - a drawbar assembly whose rear end is attached to said second frame portion by a third pivoting connection and whose front end is coupled to the rear of said motor vehicle;

    said method comprising selectively locking and unlocking the pivotal action of said first and second pivoting connections in response to preset ranges of road speeds during forward motion of the vehicle.
21. 21. The method according to claim 20 wherein:

    said second pivoting connection is a lockable turntable, and said rear axle set is a self-steer rear axle, and said method comprises:

    - at selected high road speeds, unlocking said lockable turntable forming the second pivoting connection so it is free to rebate as induced by the motion of the vehicle, and locking said self-steer rear axle into the straight-ahead position, and

    - at selected low road speeds, locking said turntable forming the second pivoting connection into its straight-ahead position and unlocking said selfsteer rear axle so it is free to steer as induced by the motion of the vehicle.
22. 22. The method according to claim 21 wherein:

    - said trailing axle set is a tandem axle set the rearmost axle of which is a selfsteer axle, and said method comprises:

    - at said high road speeds, locking said rearmost axle into the straight-ahead position, and

    - at said low road speeds, unlocking said rearmost axle so it is free to steer as induced by the motion of the vehicle.
23. 23. The method according to claim 21 or 22 wherein said motor vehicle comprises a leading semi-trailer the rearmost axle of which is a self-steer axle, and said method comprises:

    - at said high road speeds, locking said leading semi-trailer’s rearmost self-steer axle into the straight-ahead position; and at said low road speeds unlocking said leading semi-trailer’s rearmost selfsteer axle so it is free to steer as induced by the motion of the vehicle.
24. 24. The method according to claim 20 wherein:

    - said first pivoting connection is a first lockable turntable, said second pivoting connection is a second lockable turntable, and

    - said rear axle set is a self-steer axle, and said method comprises:

    - at a selected range of high road speed conditions, unlocking said first and second lockable turntables so they are free to rotate as induced by the motion of the vehicle, and locking said self-steer rear axle into the straight-ahead position.
25. 25. The method according to claim 20 wherein:

    - said first pivoting connection is a first lockable turntable,

    - said second pivoting connection is a second lockable turntable, and said rear axle set is a self-steer axle, and said method comprises:

    - at a selected range of high road speed conditions, locking said first lockable turntable into the straight-ahead position, and

    - unlocking the self-steer axle so it is free to steer as induced by the motion of the vehicle.

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26. 26. The method according to claim 20 wherein:

    said first pivoting connection is a first lockable turntable, said second pivoting connection is a second lockable turntable, and

    5 - said rear axle set is a lockable self-steer axle, and said method comprises, at a selected range of high road speed conditions:

    - unlocking said first lockable turntable so it is free to rotate as induced by the motion of the vehicle, and

    - locking said self-steer rear axle into the straight-ahead position.