CA2987210A1

CA2987210A1 - Steerable coupling linkage for a compact pulling apparatus

Info

Publication number: CA2987210A1
Application number: CA2987210A
Authority: CA
Inventors: Yvon Martel
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-11-30
Filing date: 2017-11-30
Publication date: 2019-05-30
Also published as: WO2019104436A1

Abstract

The steerable coupling linkage (106) is for use between a compact pulling apparatus (100) and a hauled unit (102) to form an articulated vehicle (104). It includes a yaw pivot mount, a roll pivot mount and pitch pivot mount that are sequentially disposed between the front end of a casing (140) and the apparatus (100). It also includes a semi-spherical towing ball (134) projecting upwards from a top outer surface (141) at the front end of the casing (140). A
transversally-extending drawbar clamping assembly (142) is provided on the casing (140) to removable affix the drawbar (130) of the hauled unit (102) on the casing (140) when ball (134) is secured inside the trailer hitch (132). A steering actuator (160) is provided inside the casing (140) to selectively control a relative angular position of the casing (140) with reference to the apparatus (100) about the yaw axis (150), thereby allowing the articulated vehicle (104) to be steered.

Description

STEERABLE COUPLING LINKAGE FOR A
COMPACT PULLING APPARATUS
TECHNICAL FIELD
The technical field generally relates to compact pulling apparatuses capable of travelling over difficult terrains, such as terrains covered with snow, sand, mud, etc.
TECHNICAL BACKGROUND
Various apparatuses have been suggested over the years for travelling on difficult terrains. Of these, some are compact pulling apparatuses such as those disclosed in U.S. Pat. Ser.
Nos. 8,453,769 and 9,821,865. Apparatuses of this sort are very useful as light means of transportation, particularly where it is difficult or even forbidden to travel using a larger vehicle. For example, in terrains with a snow-covered surface, the snow could be too powdery and/or too deep to use a snowmobile but not for a compact pulling apparatus. Another advantage of such apparatuses is that it is much more simple and easy to transport them in another vehicle than is the case with a larger and heavier vehicle, for instance a snowmobile.
Further improvements on many different aspects of compact apparatuses are always needed and desirable so as to even further improve the technology in this technical area.
SUMMARY
The general concept provided herein resides in a steerable coupling linkage for use between a compact pulling apparatus and a hauled unit arranged in tandem. The linkage couples the hauled unit behind the compact apparatus to form an articulated vehicle that can be steered through a

2 remote control, for instance a joystick controller. The hauled unit can be very quickly affixed to or removed from the apparatus using the coupling linkage.
According to one aspect, there is provided a steerable coupling linkage for use between a compact pulling apparatus and a hauled unit to form an articulated vehicle, the hauled unit having an elongated front drawbar and a trailer hitch at a front end of the drawbar, the steerable coupling linkage including: a rigid casing extending longitudinally between a front end and a rear end, the casing defining an interior space and having a top outer surface, a yaw pivot mount, a roll pivot mount and a pitch pivot mount that are sequentially disposed between the front end of the casing and the apparatus, the yaw pivot mount being arranged to pivot about a yaw axis, the roll pivot .. mount being arranged to pivot about a roll axis and the pitch pivot mount being arranged to pivot about a pitch axis, the yaw, roll and pitch axes being substantially orthogonal to one another; a semi-spherical towing ball projecting upwards from the top outer surface at the front end of the casing, the ball having a main central axis that is substantially coincident with the yaw axis, the ball being configured and disposed to be secured inside the trailer hitch; a transversally-extending drawbar clamping assembly affixed on the top surface of the casing and being spaced-apart from the ball, the drawbar clamping assembly being configured and disposed to removable affix the drawbar of the hauled unit on the casing when ball is secured inside the trailer hitch; and a steering actuator located inside the casing to selectively control a relative angular position of the casing with reference to the apparatus about the yaw axis, thereby allowing the articulated vehicle to be steered, the steering actuator having opposite ends, one end being attached on the casing and the other end being attached on the roll pivot mount.
Details on the various aspects and features of the proposed concept will become apparent in light of the detailed description which follows and the appended figures.

3 BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is an isometric view of an example of an articulated vehicle formed by a compact pulling apparatus and a hauled unit that is affixed to the compact pulling apparatus using a steerable coupling linkage based on the proposed concept;
FIG. 2 is a side view of the articulated vehicle in FIG. 1;
FIG. 3 is a semi-schematic top view of the articulated vehicle in FIG. 1;
FIG. 4 is a front isometric view of the steerable coupling linkage, the drawbar and the side plates illustrated in FIG. 1;
FIG. 5 is a rear isometric view of the steerable coupling linkage, the drawbar and the side plates illustrated in FIG. 1;
FIG. 6 is a view similar to FIG. 4 but prior to coupling;
FIG. 7 is a front isometric exploded view of only the parts of the steerable coupling linkage in FIG. 1;
FIG. 8 corresponds to FIG. 4 when the hauled unit is pivoted relative to the apparatus about the roll axis;
FIG. 9 is a top fragmentary view of the steerable coupling linkage and of the drawbar of the hauled unit illustrated in FIG. 1 affixed thereon;
FIG. 10 corresponds to FIG. 4 when the hauled unit is pivoted relative to the apparatus about the pitch axis and this motion is restricted; and

4 FIG. 11 is a view similar to FIG. 10 but where the pitch motion is unrestricted.
DETAILED DESCRIPTION
FIG. 1 is an isometric view of an example of a compact pulling apparatus 100 and a hauled unit 102 arranged in tandem so as to form an articulated vehicle 104. The hauled unit 102 is affixed to the rear of the apparatus 100 using a steerable coupling linkage 106 provided between them.
The apparatus 100 includes an endless track 110 disposed around a watertight housing 112 having an elongated form. The housing 112 extends along a longitudinal axis 114. The rotation of the track 110 around the outside of the housing 112 enables the apparatus 100 to move over a ground surface.
The housing 112 is low-slung in order to keep its center of gravity as low as possible. The track 110 can be made of rubber or some other polymer. Other materials are possible.
The apparatus 100 can be used on almost any surfaces, including paved roads, sand, snow, ice, etc.
It should be noted at this point that the reference to a "watertight" housing means that the construction of the housing 112 is watertight but this does not exclude the presence of an air ventilation circuit for circulating air inside the housing 112. For instance, the ventilation circuit can be provided to cool the interior of the housing 112 when its temperature exceeds an upper threshold, such as above 25 C. Other values are possible. The ventilation circuit can also be used to keep the interior of the housing 112 warm during cold weather conditions.
The construction of the apparatus 100 as shown in FIG. 1 is substantially similar to the one shown in Applicant's previous patents, for instance as disclosed in U.S. Pat. Ser.
Nos. 8,453,769 and 9,821,865. The entire contents of these two prior patents are incorporated herein by reference in their entirety. Nevertheless, variants are possible as well.

5 The apparatus 100 of the illustrated articulated vehicle 104 includes at least one track-driving motor inside the housing 112 for generating rotating output power to move the track 110. The motor or motors are located within the housing 112 and can be, for instance, an electric motor using electrical power coming from batteries, a fuel-powered internal combustion engine (ICE), or both. When an electric motor and an ICE are both present, the electric motor can be an electric machine having both a power generator mode where it is capable of generating electrical power using rotating output power coming from the ICE, and an electric motor mode where it is capable of generating rotating output power using electrical power coming from the batteries.
Nevertheless, one can use an electric machine that is only an electric motor (i.e. no power generator mode) in some implementations or, in others, an electric machine that is only a power generator (i.e. no electric motor mode). An apparatus such as the one shown in FIG. 1 can further include only an electric motor and no ICE (i.e. be exclusively electric) or only an ICE (i.e. no electric machine therein).
Other configurations and arrangements are possible as well.
The articulated vehicle 104 can be used for a very wide range of applications and purposes. One of them involves search and rescue emergency missions, particularly those in response to an incident occurring on a difficult and/or unstable terrain, in a confined space or in a hazardous zone. Some operations may even occur under circumstances where all these difficulties are present. An example is a rescue mission in an underground environment such as in a mine or a cave, where a victim must be pulled out of a danger zone by rescuers and then transported towards the surface over some distance through tight passages. Another example is a rescue mission following an avalanche and where the surrounding environment is still very unstable. Minimizing noise and the time spent on the scene are then critical factors.

6 Every incident has some unique characteristics and potential dangers for the rescue team. Thus, being able to conduct the search and rescue operation with the maximum efficiency under many different circumstances is always needed in any life-threatening situation.
The articulated vehicle 104 can help reaching this goal. With the articulated vehicle 104, rescuers can access a remote site very quickly, even in a very difficult environment, bring search and rescue equipment and supplies to find and/or stabilize a victim, pull a victim out of any imminent danger, and move a victim using a stretcher to bring him or her elsewhere, for instance to another evacuation vehicle and/or to other medical response personnel. Search and rescue equipment and supplies that can be carried by the articulated vehicle 104 include medical supplies, mobile life support devices, rescue equipment such as ropes, harnesses, shovels, floatation devices, blankets and fire extinguishers, to name just a few, electronic devices such as sensors, telecommunication devices, global positioning systems (GPS), etc., and any other kinds of supplies that the situation may require, including other items such as tents, food and water, heaters, etc. Variants are possible as well.
Regardless of the situation, using the articulated vehicle 104, thus with a hauled unit 102, is always .. very useful to transport a payload, persons, or both.
In some implementations, an external rack can be provided over the housing 112 of the apparatus 100, at a short minimal distance above the track 110, to receive a payload, additional batteries, etc.
In other implementations, one or more storage spaces can be provided inside the housing 112 of the apparatus 100. The storage space or spaces can be accessed by removing side panels or through .. access doors (not shown). Still, one can provide one or more additional hauled units behind the one that is affixed to the apparatus 100 by the steerable coupling linkage 106.

7 The hauled unit 102 illustrated in the example of FIG. 1 is a nonautomotive trailer that includes a main body 120 supported by two sets of ground-engaging wheels 122. It is designed for use on very rugged off-road terrains but, nevertheless, it can be used on paved roads or the like. Other configurations and arrangements are also possible. For instance, the hauled unit 102 can be in the form of a sled for use on snow or ice, where the bottom side of the body engages the ground surface.
Many other variants are possible as well.
The hauled unit 102 is low-slung in order to keep its center of gravity as low as possible. The main body 120 of the illustrated hauled unit 102 is opened at the top. It includes a transversally-disposed seat 124 where an operator can sit. It also has a joystick controller 126 for controlling the steering direction, the travel direction (forward or reverse) and the speed of the articulated vehicle 104, among other things. The joystick controller 126 can communicate with the apparatus 100 using a wired communication link, a wireless communication link, or both. A wireless communication link is used in the illustrated example and the joystick controller 126 sends electronic signals to an electronic control device located on the apparatus 100, for instance inside the housing 112. The wireless link can be established via a radio channel, an infrared channel or any other suitable method. Other configurations and arrangements are possible. Among other things, the operator does not necessarily need to be on the hauled unit 102 to control the articulated vehicle 104. The joystick controller 126 can be made removable from the hauled unit 102 and can be carried by the operator standing next the articulated vehicle 104. In some implementations, the operator could even be located at a remote location.
The hauled unit 102 includes an elongated drawbar 130 extending substantially horizontally at the front thereof. In the illustrated example, the drawbar 130 is rigidly attached to or otherwise made

8 integral with the main body 120. It is also coincident with its medial plane.
The front end of the drawbar 130 includes a trailer hitch 132. Other configurations and arrangements are also possible.
The trailer hitch 132 in the illustrated example is a generic standard hitch system, namely such as the ones that are widely commercially available for use with trailers hauled by passenger cars and light trucks. It is configured and disposed to receive a generic semi-spherical towing ball 134 (see FIGS. 6 and 7) projecting upwards at the front end of the steerable coupling linkage 106. The ball 134 is inserted through the bottom front end of the trailer hitch 132 when the hauled unit 102 is affixed to the apparatus 100, as shown in FIG. 1.
The trailer hitch 132 can be bolted, welded or otherwise rigidly secured to the front end of the .. drawbar 130. It includes an internal ball locking mechanism having a locking element that is selectively engageable with the ball 134, more particularly its bottom half, when the trailer hitch 132 is positioned over the ball 134. The ball locking mechanism is designed to selectively activate or release the engagement of the locking element with the ball 134. When engaged, the locking element prevents the trailer hitch 132 from being removed off the ball 134 but it does not normally prevent it from pivoting around the ball 134, for instance to allow steering in a conventional towing arrangement. The exact construction of the ball locking mechanism can vary from one implementation to another. In the illustrated example, the ball locking mechanism of the trailer hitch 132 includes a lever 136 that is pivotally mounted on the top portion of the trailer hitch 132.
The position of the lever 136 controls the position of the locking element therein. The lever 136 is substantially horizontal in the illustrated example, this corresponding to the locked position. Other configurations and arrangements are also possible.

9 As can be seen, the steerable coupling linkage 106 includes a rigid and longitudinally-extending casing 140 defining an internal space opened at its front end of the casing 140. The ball 134 is attached over to the front end of the casing 140 and extends upwards from the top outer surface 141 thereof (see FIG. 4, for instance). The top and bottom surfaces of the casing 140 are substantially flat in the illustrated example. Other configurations and arrangements are also possible.
The steerable coupling linkage 106 includes a drawbar clamping assembly 142 extending along the top transversal rear edge of the casing 140. The drawbar clamping assembly 142 is configured and disposed to removably hold an intermediate part of the drawbar 130 when the hauled unit 102 is affixed to the apparatus 100. The drawbar clamping assembly 142 is in a locked position in FIG. I.
The casing 140 of the steerable coupling linkage 106 is attached to the rear of the apparatus 100 using a rigid transversal bar 144 extending outside the housing 112 above the track 110. The transversal bar 144 is substantially straight and horizontal in the illustrated example. It is supported at its opposite ends using two corresponding side plates 146 projecting towards the top of the housing 112. These side plates 146 are rigidly attached to the lateral walls of the housing 112 and are obliquely-disposed toward the rear in the example. Other configurations and arrangements are also possible.
It should be noted that the transversal bar 144 is part of the steerable coupling linkage 106 in the illustrated example. However, this may not necessarily be the case in all possible implementations.
The steerable coupling linkage 106 creates three distinct pivot axes around which the relative angular position between the apparatus 100 and the hauled unit 102 can change, namely a yaw axis, a pitch axis and a roll axis. The yaw, roll and pitch axes are substantially orthogonal to one another.

10 The yaw axis is schematically illustrated in FIG. 1 at 150. The yaw axis 150 is a substantially vertical axis around which the apparatus 100 and the hauled unit 102 pivot relative to one another, thereby allowing the articulated vehicle 104 to be steered. The pitch axis is schematically illustrated at 152. It is coaxial with the transversal bar 144 in the illustrated example.
The roll axis is parallel to the longitudinal axis 114 and is coincident with the medial plane of the articulated vehicle 104 as shown. It is schematically illustrated in FIG. 2 at 154. Other configurations and arrangements are also possible.
FIG. 2 is a side view of the articulated vehicle 104 in FIG. I.
Corresponding mounts are provided to create the link between the front end of the casing 140 and the apparatus 100. The sequence, starting from the casing 140, is a yaw pivot mount, a roll pivot mount and a pitch pivot mount.
The steerable coupling linkage 106 includes a steering actuator, for instance in the form of a hydraulic actuator, positioned inside the casing 140 to vary the relative angular position between the casing 140 and the apparatus 100 about the yaw axis 150, thus the relative angular position between the apparatus 100 and the hauled unit 102 about the yaw axis 150 when the drawbar 130 is affixed to the steerable coupling linkage 106. Controlling this relative angular position results in controlling the steering direction of the articulated vehicle 104 on a continuous basis, thereby allowing the articulated vehicle 104 to move in a straight line, or to turn right or left, depending what is needed at the instant. The relative angular position with reference to the yaw axis 150 can also generally be changed when the articulated vehicle 104 is stationary. The actuator is responsive to command signals sent by a corresponding control device, for instance the joystick controller 126. More details concerning the steering actuator are given later in the present description.

11 The relative angular position between the apparatus 100 and the hauled unit 102 about the pitch axis 152 and the relative angular position between the apparatus 100 and the hauled unit 102 about the roll axis 154 are not actuated in the illustrated example. However, one or both can be limited to a given range of angles, or be prevented. Any combination is possible, depending on what is best suited for the kind of hauled unit 102, the type of terrain, the maximum travel speed, the experience of the operator, etc.
FIG. 3 is a semi-schematic top view of the articulated vehicle 104 in FIG. I.
FIG. 3 illustrates examples of a change in the relative angular position between the apparatus 100 and the hauled unit 102 about the yaw axis 150. This is governed by the actuator inside the steerable coupling linkage 106. In use, to steer the illustrated articulated vehicle 104 to the left, the actuator is extended with reference to the position it has when the articulated vehicle 104 travels in a straight line. This causes the front end of the apparatus 100 to move to the left while the rear end of the hauled unit 102 simultaneously moves to the left with reference to the longitudinal axis 114. Likewise, to steer the articulated vehicle 104 to the right, the actuator is retracted with reference to the position it has when the articulated vehicle 104 travels in a straight line. This causes the front end of the apparatus 100 to move to the right while the rear end of the hauled unit 102 simultaneously moves to the right with reference to the longitudinal axis 114.
FIG. 4 is a front isometric view of the steerable coupling linkage 106, the drawbar 130 and the side plates 146 illustrated in FIG. 1. FIG. 5 is a rear isometric view thereof. As can be seen, the trailer hitch 132 includes a sleeve portion 170 mounted onto the front end of the drawbar 130, and a ball socket portion 172, located at the front, in which the ball 134 is received.

12 FIGS. 4 and 5 also show, among other things, the front portion of the steering actuator 160 located inside the casing 140. The actuator 160 is laterally offset with reference to the medial plane so as to create a lever arm with reference to the yaw axis 150.
As can be seen in FIG. 5, the rear end of the casing 140 is closed by a protective member 156 in the illustrated example. Other configurations and arrangements are possible.
FIG. 6 is a view similar to FIG. 4 but prior to coupling. The lever 136 for operating the locking mechanism inside the trailer hitch 132 is set to its unlocked position.
FIG. 7 is a front isometric exploded view of only the parts of the steerable coupling linkage 106 in FIG. 1. The actuator 160 includes a cylinder 162 and a rod 164 connected to a piston reciprocating inside the cylinder 162. In the illustrated example, the rear end of the cylinder 162 of the actuator 160 is pivotally attached to the casing 140 using a set of bushings 186 and a vertically-disposed bolt 188. The front end of the rod 164 is pivotally connected to a swivel member 176 using a bolt 189. Other configurations and arrangements are possible.
Also, the casing 140 in the illustrated example is made of two complementary parts 180, 182 that are attached together. The part 180 is located at the top and the part 182 is located at the bottom.
They can be identical or similar to one another, as shown, for instance to simplify manufacturing.
Nevertheless, other configurations and arrangements are possible.
In the illustrated example, the ball 134 is rigidly secured over the casing 140 using a bolt 190 inserted from the bottom and engaging a threaded bore hole provided underneath the ball 134.
A spacer 192 is positioned around the ball 134. The spacer 192 restricts the motion of the ball 134 inside the ball socket portion 172. This spacer 192 is made of a rigid material, for instance a metal,

13 or substantially rigid material. The spacer 192 ofthe illustrated example is substantially C-shaped and is attached to a mounting plate 194. The mounting plate 194 will be secured by the bolt 190 which passes through a hole at the center of the mounting plate 194. The presence of the spacer 192 changes the dynamics of the locking mechanism inside the trailer hitch 132 and the movements .. of the ball 134 inside the trailer hitch 132 will then be very restricted when the locking mechanism is in its locked position. Combined with the drawbar clamping assembly 142, it allows the drawbar 130 to be tightly secured to the casing 140. Other configurations and arrangements are possible.
The actuator 160 can be seen inside the casing 140 next to its hydraulic pump unit 184. This arrangement is very compact and can be similar to the one often provided to tilt marine outboard motors. Nevertheless, other kinds of configurations and arrangements are possible. The hydraulic pump unit 184 is a self-contained device, having for instance a built-in fluid reservoir. It is powered and controlled through a wired connexion, for instance through the wire harness 185. Other configurations and arrangements are possible. Among other things, other kinds of actuators can be used.
The drawbar clamping assembly 142 is shown in an opened position in FIG. 7. As can be seen, the illustrated example includes a main arm 200 pivotally attached to a base member 202 using a hinge 204. The main arm 200 has a hook 206 cooperating with a latching mechanism 210 attached at the opposite end of the base member 202. The base member 202 includes two opposite and spaced-apart lateral slanted surfaces 212 forming a seat that prevents the drawbar 130 from moving sideways once the main arm 200 is in a closed position and locked by the latching mechanism 210.
Other configurations and arrangements are possible.

14 The swivel member 176 can be seen in FIG. 5. In the illustrated example, the swivel member 176 is pivotally connected to the casing 140 and it is coincident with both the yaw axis 150 and the roll axis 154. The yaw axis 150 is coincident with the ball 134. The swivel member 176 includes a vertically-extending hole 220 in which a vertically-extending a hollow tube 222 can be inserted.
The tube 222 is rigidly connected to the casing 140 and can rotate once inside the hole 220. Other configurations and arrangements are possible.
The swivel member 176 is also pivotally connected to a central part 232 of the transversal bar 144 using a rigid bushing 224, for instance made of metal, retained by a bolt 230.
The bushing 224 and the bolt 230 are coaxial with the roll axis 154. The threaded shank of the bolt 230 passes through .. the bushing 224 fitted inside a hole in the square-shaped central part 232 to reach a corresponding threaded hole ending just before the hole 220. The bushing 224 is made slightly longer than the width of the central part 232 and its rear end engages the front side of the swivel member 176.
Other configurations and arrangements are possible. In all instances, the roll pivot mount must be designed to resist the shocks and jars caused by uneven road surfaces or when the articulated vehicle 104 encounters obstacles. Other configurations and arrangements are possible.
FIG. 7 shows that in the illustrated example, there is an access port 226 on the top outer surface 141 of the casing 140 near to the rear end. This access port 226 can also be seen in other figures. It is provided to activate or deactivate the hydraulic system for the steering actuator 160. For instance, it is possible to juxtaposed one or more hauled units behind the first one and these additional hauled units do not necessarily need to be steered at that moment. The trailing hauled unit will simply follow the direction of its leading hauled unit if the piston inside the steering actuator 160 is in a bypass mode and is freely movable therein.

15 The illustrated example further includes two spaced-apart stoppers to limit the range of relative angular positions about the roll axis 154 between the apparatus 100 and the hauled unit 102. Each stopper include a mounting peg 234 extending parallel to the roll axis 154 and around which a resilient cushion 236 is mounted. The cushions 236 are configured and disposed to engage the upper surface of the square-shaped central part 232 of the transversal bar 144 but only if a certain relative angle is reached. They otherwise remain spaced-apart from the surface.
While one could also provide an arrangement to prevent any motion about the roll axis 154, for instance using a bolt or pin to secure to the swivel member 176 to the transversal bar 144, it was found that a partial restriction is often very desirable in rough terrains over the situation where the motion is unrestricted or is completely prevented. Among other things, having some degree of freedom about the roll axis 154 allows the apparatus 100 at the front of the articulated vehicle 104 to conform to the contour of the terrain over which it passes, thereby maintaining the track 110 in good tractive engagement with the ground. It can also improve maneuverability on rugged terrains.
For instance, the operator can lean over from the hauled unit 102 in a tight turn and this is very effective to turn due to the relative narrow width of the track 110. On the other hand, having an unrestricted motion about the roll axis 154 could likely result in situations where either the apparatus 100 or the hauled unit 102 overturns in a rugged terrain. Hence, having an arrangement that only partially limits the roll motion, in this specific context, is an approach that has many benefits. Nevertheless, other configurations and arrangements are possible. It is also possible to omit or remove this feature in some implementations.
The pitch axis 152 is coincident with the transversal bar 144 in the illustrated example. The opposite ends of the transversal bar 144 are journaled to corresponding mounting arrangements 145 (see

16 FIG. 4) located on the side plates 146, for instance bearings, bushings, etc.
Other configurations and arrangements are possible.
The illustrated example also features a pitch limiter assembly 240 to selectively limit the range of relative angular positions about the pitch axis 152. The same kind of assembly could possibility be configured to prevent any relative movement about the pitch axis 152 in some implementations.
The assembly 240 includes a bushing member 242 having a square-shaped outer surface that can engage the square-shaped central part 232 of the transversal bar 144. The bushing member 242 is mounted inside a corresponding socket 244. The two parts can be moved along the transversal bar 144 between a first position where the bushing member 242 is out of engagement with the central part 232, and a second position where the bushing member 242 is inserted over the square-shaped central part 232 to provide a torque-transmitting engagement between the transversal bar 144 and the socket 244. The socket 244 cooperates with a pin 246 radially extending from the surface of the transversal bar 144. The pin 246 cooperates with an L-shaped slot 248 provided on a sleeve portion 250 extending at the back of the socket 244. The sleeve portion 250 connects the socket 244 to a tubular holder 252 located at the corresponding end of the transversal bar 144, next to one of the side plates 146. The tubular holder 252 includes a notched end 254 having a somewhat C-shaped form. As can be seen in FIG. 5, the notched end 254 cooperates with a stopper 256 provided across the side plate 146. The interior shape of the notched end 254 and the stopper 256 restrict the angular motion of the tubular holder 252 to a limited range. Furthermore, the sleeve portion 250 and the interior of the tubular holder 252 are configured and disposed so that a torque-transmitting engagement between the sleeve portion 250 and the tubular holder 252 only occurs when the bushing member 242 is inserted over the square-shaped central part 232. The pin 246 and the L-shaped slot 248 constrict the parts to either the first position (short segment) or the second position

17 (long segment). A set of internal compression springs 260 are provided to urge the socket 244 towards the central part 232 of the transversal bar 144. This maintains the connection between the parts in the second position, but also prevents them from undesirably engaging by themselves due to shocks and vibrations in the first position. Other configurations and arrangements are possible.
FIG. 8 corresponds to FIG. 4 when the hauled unit 102 is pivoted relative to the apparatus 100 about the roll axis 154.
FIG. 9 is a top fragmentary view of the steerable coupling linkage 106 and of the drawbar 130 of the hauled unit 102 illustrated in FIG. 1 affixed thereon. It illustrates a change in the relative angular position between the apparatus 100 and the hauled unit 102 about the yaw axis 150 to steer the articulated vehicle 104 to the right. The steerable coupling linkage 106 and the drawbar 130 are shown as if they were stationary but this is only for the sake of illustration. Furthermore, also for the sake of illustration, a portion of the casing 140 was removed from the view to reveal some of the parts therein.
FIG. 9 also shows that the steerable coupling linkage 106 includes a position sensor 178 in the illustrated example. The position sensor 178 has a telescopic construction.
Both opposite ends are pivotally attached to the same parts where the ends of the actuator 160 are attached. As shown, retracting the actuator 160 will change the relative angular position about the yaw axis 150 and the length of the position sensor 178 will be reduced by a proportional amount.
This information can be sent to a control module in the form of signals indicative of the relative angular position. The information can be used to provide feedback to the operator or for assisting the operator, or both.
Other configurations and arrangements are possible as well.

18 FIG. 10 corresponds to FIG. 4 when the hauled unit 102 is pivoted relative to the apparatus 100 about the pitch axis 152 and this motion is restricted by the pitch limited assembly 240.
FIG. 11 is a view similar to FIG. 10 but where the pitch motion is unrestricted.
The present detailed description and appended figures are only examples. A
person working in this field will be able to see that variations can be made while still staying within the framework of the proposed concept.
LIST OF REFERENCE NUMERALS
100 apparatus 102 hauled unit 104 articulated vehicle 106 steerable coupling linkage 110 track 112 housing 114 longitudinal axis 120 main body (of hauled unit) 122 wheel 124 seat 126 joystick controller 130 drawbar 132 trailer hitch 134 ball 136 lever (of trailer hitch) 140 rigid outer casing 141 top outer surface (of casing) 142 drawbar clamping assembly 144 transversal bar 145 mounting arrangement

19 146 side plate 150 yaw axis 152 pitch axis 154 roll axis 156 protective member 160 actuator 162 cylinder (of actuator) 164 rod (of actuator) 170 sleeve portion (of trailer hitch) 172 ball socket portion (of trailer hitch) 176 swivel member 178 position sensor 180 top casing part 182 bottom casing part 184 hydraulic pump unit 185 wire harness 186 bushing 188 bolt 189 bolt 190 bolt 192 spacer 194 mounting plate 200 main arm 202 base member 204 hinge 206 hook 210 latching mechanism 212 slanted surface 220 hole 222 tube 224 metal bushing 226 access port

20 230 bolt 232 central part (of transversal bar) 234 mounting peg 236 cushion 240 pitch limiter assembly 242 bushing 244 socket 246 pin 248 L-shaped slot 250 sleeve portion 252 tubular holder 254 notched end (of tubular holder) 256 stopper 260 compression spring

Claims

WHAT IS CLAIMED IS:

1 A
steerable coupling linkage (106) for use between a compact pulling apparatus (100) and a hauled unit (102) to form an articulated vehicle (104), the hauled unit (102) having an elongated front drawbar (130) and a trailer hitch (132) at a front end of the drawbar (130), the steerable coupling linkage (106) including:
a rigid casing (140) extending longitudinally between a front end and a rear end, the casing (140) defining an interior space and having a top outer surface (141), a yaw pivot mount, a roll pivot mount and a pitch pivot mount that are sequentially disposed between the front end of the casing (140) and the apparatus (100), the yaw pivot mount being arranged to pivot about a yaw axis (150), the roll pivot mount being arranged to pivot about a roll axis (154) and the pitch pivot mount being arranged to pivot about a pitch axis (152), the yaw, roll and pitch axes (150, 152, 154) being substantially orthogonal to one another;
a semi-spherical towing ball (134) projecting upwards from the top outer surface (141) at the front end of the casing (140), the ball (134) having a main central axis that is substantially coincident with the yaw axis (150), the ball (134) being configured and disposed to be secured inside the trailer hitch (132);
a transversally-extending drawbar clamping assembly (142) affixed on the top outer surface (141) of the casing (140) and being spaced-apart from the ball (134), the drawbar clamping assembly (142) being configured and disposed to removable affix the drawbar (130) of the hauled unit (102) on the casing (140) when ball (134) is secured inside the trailer hitch (132); and a steering actuator (160) located inside the casing (140) to selectively control a relative angular position of the casing (140) with reference to the apparatus (100) about the yaw axis (150), thereby allowing the articulated vehicle (104) to be steered, the steering actuator (160) having opposite ends, one end being attached on the casing (140) and the other end being attached on the roll pivot mount.

2. The steerable coupling linkage (106) as defined in claim 1, wherein the pitch pivot mount includes a transversal bar (144) extending widthwise at a rear end of the apparatus (100).

3. The steerable coupling linkage (106) as defined in claim 2, wherein the transversal bar (144) has opposite ends, each end being attached to a housing (112) of the apparatus (100) through a corresponding side plate (146).

4. The steerable coupling linkage (106) as defined in claim 2 or 3, further including a pitch limiter assembly (240) to restrict a relative angular motion about the pitch axis (152).

5. The steerable coupling linkage (106) as defined in claim 4, wherein the pitch limiter assembly (240) is movable between a first and a second positon, the pitch limiter assembly (240) being disabled in the first position but being enable in the second position to create a torque-transmitting engagement between the transversal bar (144) and a stopper 256.

6. The steerable coupling linkage (106) as defined in claim 5, wherein the pitch limiter assembly (240) includes a sleeve portion (250) that is guided along and about the transversal bar (144) by a pin (246) radially-extending from the transversal bar (144) and cooperating with a guiding slot (248) provided on the sleeve portion (250).

7. The steerable coupling linkage (106) as defined in claim 5, wherein the guiding slot (248) is substantially L-shaped.

8. The steerable coupling linkage (106) as defined in any one of claims 1 to 7, further including a roll limiter arrangement to restrict a relative angular motion about the roll axis (154).

9. The steerable coupling linkage (106) as defined in claim 8, wherein the roll limiter arrangement includes spaced-apart cushions (236) projecting from the roll pivot mount to engage a surface on the pitch pivot mount.

10. The steerable coupling linkage (106) as defined in any one of claims 1 to 9, wherein the casing (140) includes a top casing part (180) and a bottom casing part (182), both casing parts (180, 182) being substantially identical to one another, the top outer surface (141) of the casing (140) being a substantially flat surface of the top casing part (180).

11. The steerable coupling linkage (106) as defined in any one of claims 1 to 10, wherein the steering actuator (160) is powered using pressurized hydraulic fluid coming from a dedicated pump (184) provided within the casing (140).

12. The steerable coupling linkage (106) as defined in any one of claims 1 to 11, further including a position sensor (178) located inside the casing (140) to generate signals indicative of the relative angular position of the steerable coupling linkage (106) with reference to the apparatus (100).

13. The steerable coupling linkage (106) as defined in claim 12, wherein the position sensor (178) has a telescopic construction and two opposite ends, one end of the position sensor (178) being attached on the casing (140) and the other end of the position sensor (178) being attached on the roll pivot mount.

14. The steerable coupling linkage (106) as defined in any one of claims 1 to 13, wherein the roll pivot mount includes a swivel member (176) that is pivotally attached to the pitch pivot mount using a rigid bushing (224) coaxially disposed with reference to the roll axis (154).

15. The steerable coupling linkage (106) as defined in any one of claims 1 to 14, wherein the yaw pivot mount includes a tube (222) extending across the front end of the casing (140), the tube (222) being coaxially disposed with reference to the yaw axis (150) and passing through the roll pivot mount.

16. The steerable coupling linkage (106) as defined in any one of claims 1 to 15, further including a spacer (192) located around the ball (134) on the top outer surface (141) of the casing (140), the spacer (192) being configured and disposed to be engaged by a bottom side of the trailer hitch (132).

17. The steerable coupling linkage (106) as defined in claim 16, wherein the spacer (192) is made of a rigid material.

18. The steerable coupling linkage (106) as defined in any one of claims 1 to 17, the drawbar clamping assembly (142) includes a main arm (200) having opposite ends, the first end of the main arm (200) being pivotally connected to a base member (202) and the second end of the main arm (200) cooperating with a latching mechanism (210).

19. The steerable coupling linkage (106) as defined in claim 18, wherein the base member (202) includes two opposite and spaced-apart lateral slanted surfaces (212) forming a seat that prevents the drawbar (130) from moving sideways once the main arm (200) is in a closed position and locked by the latching mechanism (210) to affix the drawbar (130) to the casing (140).

20. The steerable coupling linkage (106) as defined in any one of claims 1 to 19, wherein the steering actuator (160) is remotely controlled through a joystick controller (126).