CA2259862C - Trailer vehicle - Google Patents

Abstract

A trailer vehicle comprises a mechanical steering system which is responsive to a turning movement of a motive vehicle. The steering system includes a longitudinally rotatable shaft which is connected to a forward articulated extension by means of a linkage and pivot assembly. Lateral link rods extend between cranks mounted to the rotatable shaft and steering arms connected to wheel assemblies for steering the same in accordance with a turning movement of the motive vehicle. The trailer vehicle further includes a suspension system which is adapted to attenuate the noise generated by the collision of frame elements which are pivotally connected to each other.

Description

TRAILER VEHICLE

BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to wheeled vehicles and, more particularly, pertains to a wheeled vehicle adapted to be towed by a motive vehicle, such as a tractor.

2. Description of the Prior Art United States Patent No. 5,595,397, issued January 21, 1997 to Applicant discloses a steerable trailer vehicle having a main frame portion to which a rear frame portion carrying at least one pair of steerable wheels is pivotally mounted. A front frame portion is pivotally connected to the rear frame portion and is supported on the ground by two sets of wheels. The rear steerable wheels are controlled by a hydraulic system which is designed to be responsive to a turning movement of the motive vehicle to cause the rear wheels to trace an arc similar to an arc traced by the motive vehicle.
Although the steering system of the trailer vehicle described in the above mentioned patent is efficient, it has been found that there is a need for a new mechanical steering system which does not necessitate the utilisation of hydraulic circuits.
Furthermore, it would be highly beneficial to provide a suspension system which is adapted to attenuate the noise generated by the collision of the frame elements which are pivotally connected to each other.
Finally, it has been found that although the arrangement of the pivots and axles of the trailer vehicle described in the above mentioned patent is generally satisfactory, there is a need for a new pivot and axle arrangement which is adapted to enhance the distribution of the weight and the load supported by the trailer vehicle.

SUMMARY OF THE INVENTION
It is therefore an aim of the present invention to provide a trailer vehicle having a new mechanical steering system.
It is also an airn of the present invention to provide a trailer vehic _e having a new suspension mechanism.
It is still an aim of the present invention to provide a trailer vehicle having pivot shafts and axles which are arranged to efficiently distribute the weight of the vehicle and the load carried thereon.
Therefore, in accordance with the present invention, there is provided a trailer vehicle comprising a frame structure having a longitudinal axis and a forward end portion, at least one set of steerable wheels pivoted to said frame structure, a forward articulated extension provided at the forward end portion of the frame structure and adapted to be coupled to a motive vehicle such as to be responsive to a turning movement of the motive vehicle, link means connected to the forward articulated extension for communicating a rotary movement to crank means mounted to the frame structure in response to an angular movement of the forward articulated extension, and steering linkage means laterally displaceable by the crank means to cause the set of steerable wheels to trace the arc traced by the motive vehicle.
In a further construction in accordance with the present invention, the trailer vehicle comprises a frame structux-e having a longitudinal axis, at least one set of steerable wheels carried by the frame structure, a hitch pole extending forwardly of the frame structure, the hitch pole having a forward articulated extension adapted to be mounted to a hitch of a motive vehicle such as to be responsive to a turning movement of the motive vehicle, link means coiinected to the forward articulated extension for communicating a rotary movement to a pivot assembly mounted to the hitch pole about a pivot axis at right angles to the longitudinal axis of the frame structure in response to an angular movement of' the forward articulated extension, rotatable shaft means mounted to the frame structure and extending axially thereof between the set of steerable wheels, the rotatable shaft means being drivingly connected to the pivot assembly, crank means mounted to the rotatable shaft means for rotation therewith, and steering linkage means connecting the crank means and the set of steerable wheels together, whereby angular movement of the forward articulated extension will cause rotary movement of the pivot assembly and conjoint rotation of the rotatable shaft means and the crank means thereby imparting lateral displacement to the steering linkage means, causing the set of wheels to trace the arc traced by the motive vehicle.
In accordance with a general aspect of the present invention, there is provided a trailer vehicle including a frame structure having a forward end adapted to be coupled to a motive vehicle. The frame structure includes an axle extending laterally thereof. Each end of the axle pivotally mounts respective first beams. The frame structure further includes a transversal wheel mounting beam adapted to support at least one wheel at each end thereof, the transversal wheel mounting beam being connected to the first beams by bracket rneans pivoted to pin means received in slot means defined at one end of the first beams, and biasing means for normally preventing the transversal wheel mounting beam from pivoting away from the first beams.
In accordance with another general aspect of the present invention, there is provided a trailer vehicle including a frame structure having a forward end adapted to be coupled to a motive vehicle, the frame structure including an axle extending laterally thereof for pivotally supporting a first frame portion carrying at least one set of wheels, a second frame portion connected to a front end portion of the first frame portion by a pivot, and a set of intermediate wheels and a set of front wheels journaled to the second frame portion on opposed sides of the pivot, wherein the pivot is disposed relative to the axle such as to support about 60% to about 70% of the mass carried by the trailer vehicle, the remaining of the mass being supported by the wheels journaled to the first frame portion.
BRIEF DESCRIPTION OF THE DRAWINGS
Having thus generally described the nature of the present invention, reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof, and in which:
Fig. 1 is a schematic top plan view of a trailer vehicle in accordance with the present invention;
Fig. 2 is a schematic side elevational view of the trailer vehicle shown in Fig. 1;
Fig. 3 is an enlarged fragmentary rear view of a detail of the present invention;
Fig. 4 is a vertical cross-section taken along line 4-4 of Fig. 1;
Fig. 5 is a vert_Lcal cross-section similar to Fig. 4 showing different. operating positions of a suspension mechanism of the trailer vehicle;

Fig. 5a is a vertical cross-section similar to Fig. 4, but showing a variant of the present invention;
Fig. 6 is a fragmentary enlarged top plan view of a hitch pole of the trailer vehicle;
Fig. 7 is a vertical cross-section taken along line 7-7 of Fig. 6;
Fig. 8 is a fragmentary enlarged top plan view of a rear wheel steering mechanism of the trailer vehicle;
Fig. 9 is a fragmentary enlarged top plan view of the trailer vehicle showing a detail thereof;
Fig. 10 is a fragmentary front plan view of a further detail of the trailer vehicle;
Fig. 11 is a schematic top plan view of a trailer vehicle in accordance with another embodiment of the present invention; and Fig. 12 is a top plan view of a front portion of a trailer vehicle illustrating a possible location of a pivot assembly.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now referring to the drawings, and in particular to Fig. 1, a trailer vehicle in accordance with the present invention and generally designated by numeral 10 will be described.
The trailer vehicle 10 generally includes a main frame 12 comprising two elongated lateral right angle rails 14a and 14b corinected to each other by a number of transversal members 15, 16 and 18. The rails 14a and 14b are configured to support a tank (not shown) or the like. The tank may be removably mounted to the rails 14a and 14b by means of brackets (not shown).
A hitch pole 20 having a V-shaped configuration is pivotally mounted to a pair of brackets 22a and 22b depending from respective under surfaces of the rails 14a and 14b, as seen in Fig. 2.

Adjustment bolts 23 are provided at each end of the transversal member 15 to secure the hitch pole 20 into different angular, vertical positions relative to the main frame 12. The adjustment bolts 23 are threadably engaged to the threaded ends of two U-shaped members (not shown) extending under and on the inner and outer sides of the left and right branches of the hitch pole 20 and. through the transversal frame member 15. Thus, the hitch pole 20 is thereby attached to the opposed ends of the transversal member 15. Spacers (not shown) may be inserted between the main frame 12 and the hitch pole 20 to position the latter into a pre-selected angular position relative to the ma:in frame 12.
As seen in Fig. 2, an axle 24 is mounted to the main frame 12 interrially of the transversal member 18 by means of a pa:ir of lateral brackets 25a and 25b extending downwardly from the rails 14a and 14b, respectively. Longitudinally extending beams 26a and 26b are pivotally mount:ed at opposed ends of the axle 24. As seen in Figs. 1 and 9, the transversal member 18 defines a central cut-out portion 29 in which a pair of spaced-apart sleeves 27a and 27b mounted to the axle 24 are disposed. First and second diagonal struts 28a and 30a extend respectively from rear and front end portions of the longitudinally extending beam 26a to connect the same to the sleeve 27a. Similarly, first and Second diagonal struts 28b and 30b extend respectively from rear and front end portions of the longitudinally extending beam 26b to connect the same to the sleeve 27b. By so pivotally mounting the longitudinal beams 26a and 26b to the axle 24, the lateral forces transmitted to the frame structure of the trailer vehicle 10 by the wheels thereof are counterbalanced, as will be explained hereinafter.

As seen in Figs. 1 and 3 a transversal beam 32 mounts rear wheels 33a and 33b at opposed ends thereof. The transversal beam 32 is pivotally mounted to the rear ends of the beams 26a and 26b, as will be explained hereinafter.
As seen in Figs. 1 and 2, pivot shafts 42a and 42b are provided at the front ends of beams 26a and 26b and mount wheel mounting beams 44a and 44b, respectively. A pair of wheels 46a and 46b are journaled to axles 47a and 47b extending laterally from the rear ends of the wheel mounting beams 44a and 44b while a transversal mounting beam 48, provided at opposed end thereof with wheels 50a and 50b, is pivotally mounted to the front ends of the wheel mounting beams 44a and 44b.
As seen in Figs. 4 and 5, the beam 48 is connected to the front ends of the beams 44a and 44b by means of hinged brackets 34a and 34b respectively pivoted at pivot pins 36a and 36b in respective lost-motion slots 38a and 38b defined in the longitudinally extending beams 44a and 44b, respectively.
Alternatively, the lost-motion slots 38a and 38b may be defined in the hinged brackets 34a and 34b and the pivot pins 36a and 36b may extend transversally through circular holes defined at the front ends of the longitudinal extending beams 44a and 44b, as seen in Fig. 5a.
Guide members 40a and 40b, as shown in Fig.
3, enable the ends of the beams 44a and 44b to sit properly in the prescribed location on the transversal mounting beam 48. The hinged brackets 34a and 34b allow some independent movement of the front wheels 50a and 50b relative to each other.
It is noted that the transversal beam 32 is pivotally mounted to the rear ends of the beams 26a and 26b in a manner similar to that just described with respect to the transversal mounting beam 48.
Accordingly, the wheels 33a, 33b, 46a, 46b, 50a and 50b will operate independer.itly on either side of the trailer vehicle 10.
As seen from Fiqs. 1 and 9, the lateral distance between a first vertical plane passing through the wheels 33b, 46b and 50b disposed on the left side of the frame and a second parallel vertical plane passing through the pivot 42b is substantially equal to the lateral distance separating the second vertical plane from a third parallel vertical plane extending through the left sleeve 27b, thereby counterbalancing the lateral forces which are exerted on the frame of the trailer vehicle 10. As the trailer vehicle 10 is symmetrical relative to the longitudinal axis thereof, the lateral forces exerted on the right side of the frame are also counterbalanced.
Fig. 2 shows how the mass M carried by the trailer vehicle 10 is distributed to enhance the suspension characteristics thereof. In accordance with the illustrated embodiment, the pivot shafts 42a and 42b and the rear wheels 33a and 33b are disposed such as to respectively support about 62% and 38% of the mass applied at the axle 24. About 60% of the mass supported by the pivots 42a and 42b is distributed to the wheels 46a and 46b, the remaining portion of the mass supported by the pivots being distributed to the front wheels 50a and 50b. However, satisfactory results have been obtained by distributing about 60 to 70% of the mass supported by the axle 24 to the pivot shafts 42a and 42b, the rear wheels supporting the remaining portion of the mass carried by the trailer veh_Lcle 10. In this case, the wheels 46a and 46b may support about 50 to 70% of the mass distributed to the pivot shafts 42a and 42b.

The maj or portion of the mass M is distributed to the rear wheels 33a and 33b to minimise the percentage of' the mass M supported by the front wheels 50a and 50b, thereby preventing the latter from sinking in the soil when the trailer vehicle 10 is displaced on a soft surface. Thus the trailer vehicle 10 can move easily over soft ground.
As seen in Fig. 1, a spring mechanism is provided at each rear end of the beams 26a and 26b and at each front end of t:he wheel mounting beam 44a and 44b for eliminating or at least attenuating the noise resulting from the collision of the beams 26a,26b and 44a,44b against the transversal wheel mounting beams 32 and 48, respectively. As all the above mentioned spring mechanisms or noise attenuating devices 52 are similar, only one of such devices will be described.
Figs. 4 and 5 illustrates a noise attenuating device 52 provided at the front end of the wheel mounting beam 4=4b. The noise attenuating device 52 includes a spring 54 mounted on a pin 56. A
L-shaped front plate 59 is provided on the front end of the beam 44b and includes a flange 58. The pin 56 passes through a hole defined in the flange 58. The wheel mounting beam 48 includes a bracket 60. The pin 56 also passes through a hole defined in bracket 60.
A retaining ring 62 and a first nut 64 are provided at an upper end of the pin 56 to hold the spring 54 in compression against the upper surface of the flange 58. A nut 66 is threadably engaged with a lower end of the pin 56 and urges against an under surface of the bracket 60 to normally prevent the transversal wheel mounting beam 48 from pivoting away from the beams 44a and 44b. However, as the retention force of the spring is less than the cumulative weight of the transversal beam 48 and of the wheel 50b, the transversal beam 48 will be subject to limited pivot movement relative to the beams 44a and 44b to maintain the wheels 50a and 50b in contact with the soil, as seen in Fig. 5.
Referring now more specifically to Figs. 1, 6 and 7, there is shown a steering mechanism which is responsive to the direction of movement of a motive vehicle, such as a tracizor, pulling the trailer vehicle 10.
The articulated axle assembly of the rear wheels 33a and 33b and thE: front wheels 50a and 50b is provided as being at the ends of transversal wheel mounting beams 32 and 48, respectively.
More particularly, as seen in Fig. 3, the transversal wheel mounting beam 32 is provided at opposed ends thereof with bearing brackets 70a and 70b which support respective hinge pins to which bearings 72a and 72b are journaled. The wheel axles 74a and 74b are fixed to bearings 72a and 72b.
Similarly, the transversal wheel mounting beam 48 is provided at opposed ends thereof with bearing brackets 76a and 76b which support respective hinge pins to which bearings (not shown) are journaled. Similar to the rear wheel axles 74a and 74b, the front wheel axles 78a and 78b are fixed to the bearings.
There will now be described the mechanical system which is used to steer the wheels 33a, 33b, 50a and 50b.
As seen in Figs. 1, 6 and 7 the hitch pole 20 is provided with a forward articulated extension 80 adapted to be coupled to a towbar B of a motive vehicle. More particularly, the forward articulated extension 80 includes an articulated member 81 which is pivotally mounted to a U-shaped front portion 82 of the hitch pole 20 for rotation about a vertical axis. As seen in Fig. 7, the U-shaped front portion 82 is fixedly mounted on a shaft 83 which is in turn - 1C) -pivotally mounted in the longitudinal axis of a tube 85 secured to the V-shaped portion of the hitch pole 20. The U-shaped front portion 82 and the articulated member 81 define a vertical passage through which a lock pin 84 may be inserted to attach the towbar B
which is disposed between the legs of the U-shaped portion 82 of the trailer vehicle 10, as seen in Fig.
7.
The articulated nlember 81 is provided at a front end thereof with a pair of downwardly extending pins 86a and 86b which are disposed to receive therebetween the towbar B of the motive vehicle.
Thus, when the motive vehicle will turn to the left, the articulated member 8:1 will be rotated in a counterclockwise direction about the pivot axis of the lock pin 84. If, the motive vehicle turns to the right, the articulated mernber 81 will rotate in a clockwise movement. The articulated member 81 is provided with a hinge 88 having a longitudinal axis to facilitate connection of the articulated member 81 to the drawbar B of the motive vehicle.
The articulated extension 80 further comprises a parallelogram linkage 92 for conveying the motion transmitted to the articulated member 81 by the motive vehicle to a pivot assembly 90 mounted to the hitch pole 20. More specifically, the linkage includes a pair of link rods 94a and 94b. Ball joints 93a and 93b are provided for connecting the front ends of the link rods 94a and 94b to a pair of arms 96a and 96b extending laterally from the articulated extension 80. A plate 98 secured to a pivot shaft 100 is connected at opposed ends thereof to the rear ends of the link rods 94a and 94b by means of ball joints 95a and 95b. The ball joints 93a, 93b, 95a and 95b allow a rotation of about 20 degrees of the U-shaped portion 82 with the shaft 83 about the longitudinal axis thereof.

As seen in Fig.. 6, the front ends of the link rods 94a and 94b are equidistant from the pivot axis of the articulated extension 80, while the rear ends thereof are equidistant from the rotating axis of the pivot shaft 100. Therefore, when the articulated member 81 rotates in a counterclockwise direction, the pivot shaft 100 will rotate in the counterclockwise direction. Similarly, if the articulated member 81 rotates in a clockwise direction, the pivot shaft 100 will rotate in the clockwise direction.
The pivot shaft 100 is connected to an axially extending steering shaft assembly 102 by means of a gear box 104 adapted to couple intersecting shafts. As shown in Fig. 1, the gear box 104 is configured to transfer the direction of rotation of the pivot shaft 100 to the shaft assembly 102.
The steering shaft assembly 102 includes a number of shaft sections mounted in an end to end relationship by means of ur.Liversal joints in order to accommodate relative changes in altitude between the frame portions forming the frame structure of the trailer vehicle 10.
More particularly, a universal joint 105 connects the first shaft section 106 to a second shaft section 108 supported under the main frame 12.
A second universal joint 110 connects the second shaft section 108 to a third shaft section 112 connected at the opposed end thereof to a fourth shaft section 114 by means of joint 116 and the fourth shaft 114 is jour=naled to the transversal wheel mounting beam 48. A universal joint 118 is provided for connecting the fourth shaft section 114 to a fifth shaft section 120 connected at the opposed end thereof to a sixth shaft section 122 by means of the universal joint 124. The sixth shaft section 122 is supported under the transversal member 18 and is connected at opposed end thereof to a seventh shaft section 126 by means of the universal joint 128.
Finally, a universal joint 130 connects the seventh shaft section 126 to a eighth shaft section 132 supported by the transversal wheel mounting beam 32.
As seen in Fig. 10, a plate 134 acting as a crank is mounted on the fola.rth shaft section 114 for rotation therewith. A first link rod 136a is connected at a first end thereof to the plates 134 and at a second end thereof to a steering arm 138a extending forwardly from !:he bearing to which the front wheel axle 78a is secured. Similarly, a second link rod 136b is connected at a first end thereof to the plate 134 and at a second end thereof to a steering arm 138b extending forwardly from the bearing to which the front wheel axle 78b is secured.
The first ends of the link rods 136a and 136b are equidistant from the rotating axis of the fourth shaft section 114. The lirik rods 136a and 136b are connected to the plate 134 and the steering arms 138a and 138b by ball joints.
As seen in Fig. 1, when the steering shaft assembly 102 is rotated in the counterclockwise direction in response to a left turn of the motive vehicle, the link rods 136a and 136b are laterally displaced, thereby causing the front wheels 50a and 50b to pivot in the direction the motive vehicle steers to trace an arc sirnilar to an arc traced by the motive vehicle.
It is understood that in the event that the gear box 104, provided for connecting the pivot shaft 100 to the steering shaft assembly 102, transmit a rotation to the shaft assembly 102 in a direction inverse to the direction of rotation of the pivot shaft 100, the steering arrns 138a and 38b, the plate 134 and the link rods 136a and 136b would be disposed - 1:3 -behind the front wheels 50a and 50b, rather than in front, to steer the front wheels in the same direction as the motive vehicle turn.
It is also noted that since the first ends of the link rods 136a and 136b are equidistant from the rotating axis of the fourth shaft sections 114, the lateral displacement of the link rod acting on the wheel which is located at the exterior of the arc traced by motive vehicle, will be slightly greater than that of the other link rod, thereby improving the lateral stability of the trailer vehicle 10 when turning.
The steering cont.rol of the rear steerable wheels 33a and 33b, as shown in Figs. 1 and 3, is accomplished by means of a pair of link rods 142a and 142b extending laterally from a plate 140 mounted on the steering shaft assembly 102 for rotation therewith. The link rods 142a and 142b are connected at opposed ends thereof to steering arms 144a and 144b extending rearwardly from bearings 72a and 72b.
Thus, as seen in Fig. 1, when the steering shaft assembly 102 is rotated in the counterclockwise direction in response to a left turn of the motive vehicle, the link rods 142a and 142b are laterally displaced, thereby causing the rear wheels 33a and 33b to pivot in the opposite direction the motive vehicle steers to trace an arc similar to an arc traced by the latter.
It is understood that in the event that the gear box 104, provided for connecting the pivot shaft 100 to the steering shaft assembly 102, transmit a rotation to the shaft assembly 102 in a direction inverse to the direction of rotation of the pivot shaft 100, the steering arms 144a and 144b, the plate 140 and the link rods 142a and 142b would be disposed in front of the rear wheels 33a and 33b, rather than behind, to steer the front wheels in the opposite direction of the motive vehicle turn.
However, in any case, the front steering arms 138a, 138b and the rear steering arms 144a, 144b must always extend in opposite directions to ensure that the front wheels 50a, 50b and the rear wheels 33a, 33b pivot in opposite directions. Indeed, if the front steering arms 138a arid 138b extend in front of the front wheels 50a and 50b, the rear steering arms 144a and 144b will extenci rearwardly of the rear wheels 33a and 33b, and vice versa.
As seen in Figs. 1 and 3, springs 146a and 146b are provided between vertical plates 148a and 148b extending from the top surfaces of the rear steering arms 144a and 144b and bracket 149a and 149b extending rearwardly from the bearing brackets 70a and 70b. The springs 146a and 146b act as stabilisers and also provide assistance in returning the wheels 33a and 33b to their original position parallel to the longitudinal axis of the trailer vehicle 10, wherein the same is displaced in a linear direction.
As seen in Fig.. 1, the front steering wheels 50a and 50b are also provided with spring stabilising units. More specifically, springs 150a and 150b are mounted between first brackets 152a and 152b extending rearwardly f:rom the bearings to which the front wheel axles 78a and 78b are mounted and second brackets 154a and 154b mounted to a rear side of the bearing brackets 76a and 76b.
Fig. 8 illustrates an alternative linkage system which may be used to steer the rear wheel 33a and 33b of the trailer vehicle 10. The linkage system comprises a first link rod 156 connected at a first end thereof to the plate 140 and at opposed end thereof to the rear steeririg arm 144b. A second link rod 158 extends between the steering arms 144a and 144b to form a parallelogram linkage, thereby - l~i -ensuring parallel movement of the rear wheels 33a and 33b.
Referring to Fig. 11, there will now be described a second embodiment of the steering mechanism of the present invention.
Instead of using a rotatable steering shaft assembly as described hereinbefore, a system of links and cranks may be used to connect the articulated member 81 to the front and rear steerable wheels 33a, 33b, 50a and 50b.
More specifically, as schematically illustrated in Fig. 11, a parallelogram linkage 202 is provided for conveying the motion transmitted to the articulated member 81 by the motive vehicle to a crank assembly 204 mounted the transversal wheel mounting beam 48. The crank assembly 204 includes a substantially horizontal plate 206 mounted for rotation about an upwardly extending pivot 208 connected to the wheel mounting beam 48.
The linkage 202 rnay include a pair of rods 210a and 210b having front ends connected to arms 96a and 96b extending latera:Lly from the articulated member 81, and rear ends connected to the plate 206.
Therefore, when the articulated member 81 rotates in a counterclockwise direction, as illustrated in Fig.
11, the plate 206 will rotate in the counterclockwise direction.
A first link rod 212a is connected at a first end thereof to a front portion of the plate 206, i.e. in front of the :pivot 208, and at a second end thereof to the steering arm 138a. Similarly, a second link rod 212b is connected at a first end thereof to the front portion of the plate 206 and at a second end thereof to the steering arm 138b.
The link rods 212a and 212b may be connected to the plate 206 and the steering arms 138a and 138b by ball joints or the like.

As seen in Fig. 11, when the plate 206 is rotated in the counterclockwise direction in response to a left turn of the motive vehicle, the link rods 212a and 212b are late.rally displaced, thereby causing the front wheels 50a and 50b to pivot in the direction the motive vehicle steers to trace an arc similar to an arc traced by the motive vehicle.
A second pair of links 214a and 214b connect the plate 206 to a second crank assembly 216 mounted to a bracket 217 extending rearwardly from the transversal wheel mounting beam 32. The second crank assembly 216 includes a substantially horizontal plate 218 mounted for rotation about a pivot 220 extending upwardly from the bracket 217.
Thus, the links 214a and 214b will convey the motion transmitted to the plate 206 by the articulated member 81 to the plate 218 of the second crank assembly 216. Indeed, as seen in Fig. 11, when the plate 206 is rotated in the counterclockwise direction, the plate 218 is also rotated in the counterclockwise direction.
A first link rod 222 is connected at a first end thereof to a front: portion of the plate 218 and at a second end thereof to the steering arm 144b extending rearwardly from the wheel pivot assembly of the wheel 33b. A second link rod 224 extends between the steering arms 144a and 144b to form a parallelogram linkage, thereby ensuring parallel movement of the rear wheels 33a and 33b.
By connecting the link rod 222 to a front portion of the plate 218 and to the steering arm 144b, which extend rearwardly from the pivot of the rear wheel 33b, the rear wheels 33a and 33b will rotate in a direction opposite to that of the front wheels 50a and 50b, thereby enabling the trailer vehicle 10 to trace an arc similar to an arc traced by the motive vehicle. For instance, the counterclockwise rotation of the articulated member 80 will cause the counterclockwise rotation of the plates 206 and 218, thereby causing the link rod 222 to push on the steering arm 144b to steer the rear wheels 144a and 144b in a direction opposite to the motive vehicle turn.
It is understood that the links 210a, 210b, 214a and 214b may include a number of link sections connected in an end to end relationship by attachment suitable to accommodate relative motions between the various frame portions forming the frame structure of the trailer vehicle 10. Furthermore, the links 210a, 210b, 214a and 214b may also be provided in the form of cables.
Furthermore, it is, also understood that the forward articulated extension 80 may include a system of cables or chains extending between the motive vehicle and the pivot assernbly 90 or the plate 206 instead of the above described articulated member 81.
For instance, a parallelogram linkage could be used to transmit a change of direction of the motive vehicle to the pivot assembly 90 or the plate 206.
Figure 12 illustrates another construction of the present invention wherein the pivot assembly 90 is mounted to the transversal member 15 by means of a bracket 226 instead of being mounted to the hitch pole 20 as described hereinbefore.
Finally, although the present invention has been described in the context of a trailer vehicle having three sets of wheels, it is understood that the present invention may be used in connection with a trailer vehicle having morle or less than three sets of wheel s .

Claims (26)

1. A trailer vehicle comprising a frame structure having a longitudinal axis and a forward end portion, at least one set of steerable wheels pivoted to said frame structure, a forward articulated extension provided at said forward end portion of said frame structure and adapted to be coupled to a motive vehicle such as to be responsive to a turning movement of the motive vehicle, link means connected to said forward articulated extension for communicating a rotary movement to crank means mounted to said frame structure in response to an angular movement of said forward articulated extension, and steering linkage means laterally displaceable by said crank means to cause said set of steerable wheels to trace the arc traced by the motive vehicle, wherein said set of steerable wheels is mounted to axle means, said axle means also supporting said crank means.

2. The trailer vehicle defined in claim 1, wherein the forward articulated extension comprises a coupling mounted to said forward end portion for pivotal movement relative to said frame structure about said longitudinal axis, and an articulated member pivotally mounted to said coupling for pivotal movement about an axis perpendicular to said longitudinal axis, said articulated member being adapted to be releasably engaged with a drawbar of a motive vehicle so as to be rotated about said axis by said drawbar in response to a turning movement of the motive vehicle, the articulated member being drivingly connected to an input shaft of a gear box by link means, the gear box having an output shaft connected to a steering shaft assembly driving said crank means, the steering shaft assembly including a plurality of shaft sections interconnected in an end-to-end relationship by universal joints.

3. A trailer vehicle as defined in claim 1, wherein said set of steerable wheels is mounted to axle means, said crank means being disposed between said steerable wheels in the vicinity of said axle means thereof.

4. A trailer vehicle as defined in claim 1, wherein said set of steerable wheels at least include one left wheel and one right wheel disposed on an axis extending transversally of said frame structure, said left and right wheels being respectively pivotally connected to said frame structure by means of left and right wheel pivot assemblies, said left and right wheel pivot assemblies each including a steering arm, and wherein said steering linkage means extend laterally from said crank means to said steering arms of said left and right wheel pivot assemblies, whereby movement of said forward articulated extension will cause rotary movement of said crank means thereby imparting lateral displacement to said steering linkage means, causing said set of steerable wheels to trace the arc traced by the motive vehicle.

5. A trailer vehicle as defined in claim 4, wherein said left and right wheel pivot assemblies are disposed at opposed ends of a wheel axle.

6. A trailer vehicle as defined in claim 5, wherein said crank means is supported by said wheel axle.

7. A trailer vehicle as defined in claim 1, wherein said at least one set of steerable wheels include first and second sets of steerable wheels, said first set of steerable wheels being disposed in front of a transversal median axis of said frame structure, while said second set of steerable wheels being disposed behind said median axis, said first and second sets of steerable wheels each including left and right wheels, said left and right wheels of said first set of steerable wheels being mounted to respective first wheel axle assemblies, said left and right wheels of said second set of steerable wheels being mounted to respective second wheel axle assemblies, said first and second wheel axle assemblies being pivotally mounted to said frame structure, each said first wheel axle assembly being provided with a first steering arm, each said second wheel axle assembly being provided with a second steering arm, wherein said crank means include first and second crank means, and wherein said steering linkage means include first and second linkage means, said first linkage means being connected to said first steering arms of said first wheel axle assemblies and to said first crank means such as to cause said first set of steerable wheels to pivot in the direction of the motive vehicle turn tracing the arc of the motive vehicle, said second linkage means being connected to said second steering arms of said second wheel axle assemblies and to said second crank means such as to cause said second set of steerable wheels to pivot in a direction opposite to that of said first set of steerable wheels while tracing the arc of the motive vehicle.

8. A trailer vehicle as defined in claim 7, wherein said first and second crank means rotate in a same direction, said first and second linkage means being respectively connected to said first and second crank means such as to be laterally displaced in a same direction, and wherein said first and second steering arms extend in opposite directions generally along said longitudinal axis of said frame structure.

9. A trailer vehicle as defined in claim 8, wherein said first and second crank means are mounted for rotation on rotatable shaft means extending axially of said frame structure between said set of steerable wheels, said rotatable shaft means being drivingly connected to said forward articulated extension.

10. A trailer vehicle as defined in claim 9, wherein said first steering arms extend forwardly from said first wheel axle assemblies, whereas said second steering arms extend rearwardly from said second wheel axle assemblies, and wherein said first linkage means is located in front of said first wheel axle assemblies, while said second linkage means is located behind said second wheel axle means.

11. A trailer vehicle as defined in claim 9, wherein said forward articulated extension is linked to a pivot assembly which is in turn drivingly connected to said rotatable shaft means.

12. A trailer vehicle as defined in claim 8, wherein said first and second crank means rotate about respective rotational axes which are substantially perpendicular to pivot axes of said steerable wheels.

13. A trailer vehicle as defined in claim 12, wherein said first steering arms extend forwardly from said first wheel axle assemblies, whereas said second steering arms extend rearwardly from said second wheel axle assemblies, and wherein said first linkage means connect a front portion of said first crank means to said first steering arms, while said second linkage means connect a front portion of said second crank means to said second steering arms.

14. A trailer vehicle as defined in claim 13, wherein a plane of rotation of said second crank means is disposed behind said second wheel axle assemblies, and wherein said first linkage means are connected to said first crank means in front of said rotational axis thereof, said second linkage means being connected to said second crank means in front of said rotational axis thereof.

15. A trailer vehicle as defined in claim 14, wherein a plane of rotation of said first crank means is disposed substantially in front of said first wheel axle means.

16. A trailer vehicle comprising a frame structure having a longitudinal axis and a forward end portion, at least one set of steerable wheels carried by said frame structure, a forward articulated extension provided at said forward end portion of said frame structure, said forward articulated extension including a coupling mounted to said forward end portion for pivotal movement relative to said frame structure about said longitudinal axis, and an articulated member pivotally mounted to said coupling for pivotal movement about an axis perpendicular to said longitudinal axis, said articulated member being adapted to be releasably engaged with a drawbar of a motive vehicle so as to be rotated about said axis by said drawbar in response to a turning movement of the motive vehicle, link means connected to said articulated member for communicating a rotary movement to said pivot assembly in response to an angular movement of said forward articulated extension, rotatable shaft means mounted to said frame structure and extending axially thereof between said set of steerable wheels, said rotatable shaft means being drivingly connected to said pivot assembly, crank means mounted to said rotatable shaft means for rotation therewith, and steering linkage means connecting said crank means and said set of steerable wheels together, whereby angular movement of said articulated member will cause rotary movement of said pivot assembly and conjoint rotation of said rotatable shaft means and said crank means thereby imparting lateral displacement to said steering linkage means, causing said set of wheels to trace the arc traced by the motive vehicle.

17. A trailer vehicle as defined in claim 16, wherein said link means include a pair of rods having first and second ends respectively connected to said forward articulated extension and said pivot assembly, said first ends of said rods being equidistant from said pivot axis of said forward articulated extension and said second ends thereof being equidistant from said pivot axis of said pivot assembly.

18. A trailer vehicle as defined in claim 17, wherein said forward articulated extension includes a pair of spaced-apart pin means for receiving therebetween a drawbar of the motive vehicle.

19. A trailer vehicle as defined in claim 18, wherein said forward articulated extension is provided with a hinge to facilitate connection of said forward articulated extension to the drawbar of the motive vehicle.

20. A trailer vehicle as defined in claim 16, wherein said at least one set of steerable wheels include first and second sets of steerable wheels, said first set of steerable wheels being disposed in front of a transversal median axis of said frame structure, while said second set of steerable wheels being disposed behind said median axis, each said wheels of said first and second set of steerable wheels being mounted to a wheel axle assembly pivoted to said frame structure about a substantially vertical pivot axis, and wherein said crank means include first and second crank means respectively connected to first and second linkage means, said first linkage means being connected to a first steering arm fixed to each said wheel axle assembly of each said steerable wheels of said first set of steerable wheels, said second linkage means being connected to a second steering arm fixed to each said wheel axle assembly of said steerable wheels of said second set of steerable wheels, said first and second steering arms extending in opposite directions generally along said longitudinal axis of said frame structure, whereby said first set of steerable wheels may be pivoted in the direction of the motive vehicle turn tracing the arc of the motive vehicle, while said second set of steerable wheels may be pivoted in a direction opposite to that of said first set of steerable wheels while tracing the arc of the motive vehicle.

21. A trailer vehicle as defined in claim 20, wherein said pivot assembly includes an elongated rotatable member which is connected at a lower end thereof to said rotatable shaft means by a gear transmission system adapted to couple shafts having intersecting axes, said gear transmission system being adapted to transfer the direction of rotation communicated to said elongated rotatable member, and wherein said first steering arms extend forwardly from said axle assemblies of said steerable wheels of said first set of steerable wheels, whereas said second steering arms extend rearwardly from said wheel axle assemblies of said steerable wheels of said second set steerable wheels.

22. A trailer vehicle as defined in claim 20, wherein said first linkage means include a first link having a first end connected to said first crank means and a second end connected to one of said first steering arms, and a second link having a first end connected to said first crank means and a second end connected to the other of said first steering arms, and wherein said second linkage means include a first link having a first end connected to said second crank means and a second end connected to one of said second steerable arms, and a second link extending between said second steering arms.

23. A trailer vehicle as defined in claim 22, wherein said first ends of said first and second links are equidistant from a rotating axis of said rotatable shaft means.

24. A trailer vehicle as defined in claim 16, wherein spring means are provided between said set of steerable wheels and said frame means to provide assistance in returning said set of steerable wheels to an original position thereof after having been pivoted in a given direction.

25. A trailer vehicle as defined in claim 24, wherein said set of steerable wheels are mounted onto respective wheel axle assemblies pivoted to the frame about a substantially vertical axis, each said axle assembly including bracket means extending therefrom in a direction parallel to said longitudinal axis of said frame structure when said trailer vehicle is displaced in a linear direction, and wherein said spring means include at least first and second return springs, said first return spring extending between said bracket means of one of said axle assembly and said frame structure, said second return spring extending between said frame structure and said bracket means of the other of said axle assemblies.

26. A trailer vehicle as defined in claim 16, wherein said at least one set of steerable wheels include first and second pairs of steerable wheels, said first and second pairs of steerable wheels being respectively mounted to first and second frame portions of said frame structure, said first and second frame portion being pivotally connected to each other, and wherein said rotatable shaft means include a number of shaft sections connected in an end to end relationship by attachment means adapted to accommodate relative motions between said first and second frame portions, while being capable of transmitting rotational motion between said shaft sections.