CA1143406A - Self-steering converter dolly - Google Patents
Self-steering converter dollyInfo
- Publication number
- CA1143406A CA1143406A CA000411442A CA411442A CA1143406A CA 1143406 A CA1143406 A CA 1143406A CA 000411442 A CA000411442 A CA 000411442A CA 411442 A CA411442 A CA 411442A CA 1143406 A CA1143406 A CA 1143406A
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- Canada
- Prior art keywords
- dolly
- frame
- cam
- sub
- frames
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
The invention provides a self-steering converter dolly that in operation is releasably connected to the rear of a forward vehicle, such as a tractor-trailer combination, the dolly supporting the front end of a towed rearward vehicle, such as a second or "pup" trailer, via a fifth wheel connection and so that the vehicles are in tandem. The connecting means between the dolly frame and the forward vehicle frame consist of two transversely-spaced connectors that permit free pitching movement between the two frames but without substantial rolling or yawing movements between the two frames. The wheels of the dolly are mounted for steering and are urged to the neutral or straight-ahead position by a centering device. Means for releasably connecting the dolly and the forward vehicle for the required movement may comprise two transversely-spaced upwardly opening loop members on the dolly each engagable by a respective hook member on the frame of the forward vehicle.
The invention provides a self-steering converter dolly that in operation is releasably connected to the rear of a forward vehicle, such as a tractor-trailer combination, the dolly supporting the front end of a towed rearward vehicle, such as a second or "pup" trailer, via a fifth wheel connection and so that the vehicles are in tandem. The connecting means between the dolly frame and the forward vehicle frame consist of two transversely-spaced connectors that permit free pitching movement between the two frames but without substantial rolling or yawing movements between the two frames. The wheels of the dolly are mounted for steering and are urged to the neutral or straight-ahead position by a centering device. Means for releasably connecting the dolly and the forward vehicle for the required movement may comprise two transversely-spaced upwardly opening loop members on the dolly each engagable by a respective hook member on the frame of the forward vehicle.
Description
3~6 SELF-STEERING CONVER~R DOLLY
~ield of the Invention .
This invention is concerned ~ith improvements in and relating to transport converter dollies of the kind employed for releasable tandem connection of a rearward vehicle to a forward vehicle.
Review of the Prior ~rt The tandem connection toge-ther of two vehicles, particularly a tractor/trailer combination and a second trailer, is of continuing commercial interest, owing to the cost savings that are possible, and accordingly there have been a substantial number of prior proposals disclosing different equipment for this purpose. Despi-te the number of such proposa]s that have been made relatively few such -tandem rigs are in use at this time. A ~undamental problem has been the apparent need hi-~herto to accept either a certain amount of instability in the tandem connection, or else a considerable amount of tire wear with the forward wheels of the rearward vehicle. Thus, it is found that if the dolly is rigidly connected to the frame of the forward trailer, so as to form in effect an extension thereof, the rear trailer being mounted on the dolly by a fifth wheel, then high tire wear is obtained. If the dolly is connected to the forward trailer so as to pivot about a vertical axis the tire wear is reduced, but the presence of two closely~spaced vertical pivots between the two trailers introduces an undesirable instability that has been known to result in -the vehicles overturning or jackknifing.
A self-steering dolly that addresses this problem is described and claimed in our prior Canadian Patent Serial No.
1,108,203, issued 1st September 1981 to Auto Steering Trailers Limited, comprising a dolly frame that is releasably but rigidly connected to the frame of the forward vehicle by which the dolly and the rearward vehicle are to be towed. A fifth wheel connection mounted on the dolly rame releasably receives the front end of the rearward vehicle, and the dolly runs on a pair of road wheels mounted by respective stub axles with link means connecting the stub axles for steering movement about their respective axes under the effect of sideways-directed forces applied to the road wheels by movement of the forward vehicle as it is steered away from a straight line~ Centering means are connected between the link means and the dolly frame and urge the road wheels to a centered straight ahead attitude.
Definition of the Invention .
It is therefore an object of the invention to provide a new transport converter dolly for releasable tandem connection of two vehicles.
It is a more specific object to provide such a dolly which will provide a stable connection between the two vehicIes and yet will minimize the amount of tire wear with the dolly wheels.
.
.~
, 34C~
In accordance with the present invention there is provided a transport for releasable tandem connection of a rearward vehicle to a forward vehicle comprising:
a dolly frame;
means at the forward end of the dolly frame for releasably connecting the dolly frame to the frame of the forward vehicle by which the dolly and the rearward vehicle are to be towed;
the said connecting means comprisng a pair of transversely-spaced connectors attaching the dolly frame to the forward vehicle frame for free pitching movement between the two frames but without substantial rolling or yawing movements between the two frames;
a fifth wheel connection mounted on the dolly frame to releasably receive the front end of the rearward vehicle;
a dolly sub-frame mounted beneath the dolly fra~e by a turntable bearing for steering pivoting rotation about a respecti~e vertical steering pivot axis of the turntable bearing;
a dolly axle;
a spring suspension connected to the dolly sub-frame and the dolly axle and mounting the dolly axle to the dolly sub-frame;
at least two road wheels mounted by the dolly axle and on which the dolly runs; and ~ _ 3 _ . :.
i~
' 43~6 celltering means connected between the dolly fra~lle and the dolly sub-~rame, the centering means permitting pivoting steering movement of the dolly sub-frame and the road wheels about said vertical axis under the effect of sideways-directed forces applied to the road wheels by movement of the forward vehicle as it is steered away from a straight line, and urging the road wheels to a centered straight ahead attitude.
- 3a -~ , ~ ~ ~ 3 ~ 6 The said releasable connecting means may comprise a pair of transversely-spaced, upwardly-opening loop members mounted on one of the frames to extend longitudinally therefrom, and respective transversely-spaced hook members mounted on the other frame so that each hook member hooks into a respective loop member and thereby attaches the dolly frame to the forward vehicle frame for the said free pi-tching mo~ement between the two frames but without substantial rolling or yawing movements between the two frames.
Descriptio~ of the Drawings Self-steering converter dollies which are particular preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein:-FIGURE l is a side elevation showing a tractor/trailer combination and a second trailer e~ploying -the dolly of the invention between the two trailers;
~ IGURE 2 is a plan view from above of a dolly of the invention, showing the centering device employed with -the dolly in an "off-centre" position, the fifth wheel connecting plate being omitted for clarity of illustration, FIGURE 3 is a side elevation of the dolly of Figure 2, the centering device being in the "cen-tered" position, FIGURE 4 is a perspective view to show the part of :
:: :
~34(~6 the dolly connecting means carried by the forward vehicle and its cooperation with the part thereof carried by the dolly, and FIGURE 5 is a plan view of another form of ~olly to show the application of the connecting means of the invention to this s another dolly.
Description of the Preferred Embodimen~s Figure 1 illustrates a typical application of a transport dolly 10 of the in~ention wherein the tractor 12 of a tractor/-trailer combination has the forward trailer 14 coupled thereto via a fifth wheel 16, while a second rear trailer 18 is coupled to ~he forward trailer via the dolly. Referring now more specifically to Figures 2 and 3 the dolly consists of a short rigid rectangular frame 20 having a fifth wheel connecting plate 22 mounted on its upper surface about horizontal pivots Z4. The longitudinal position of the fi~th wheel plate is moved as required for ad~uct-ment of the draw bar weight that is transferred to the forward vehicle. Another short rigid rectangular dolly sub-frame 26 is mounted ~eneath t^~-e frame 20 and is connected thereto by a turn-table bearing 28 for relative rotation about a vertical steering axis 30. A transverse trailing axle 32 carrying running wheels 34 is mounted beneath the su~-frame 26 to th~ rear of the steering axis 30 by any conventional suspension system, which in this embodiment is illustrated as consisting of downward extending hangers 36 and 38 (Figure 2), springs 40 and trailing links 42 to which the axle 32 is clamped. The suspension permits the wheels to move up and down under control of the springs 40 and the usual shock-absorbers (not shown), but constrains them to run parallel to the longitudinal centre-line of the dolly sub-frame as it ~3~
pivots about the a~is 30. In other embodiments other types of suspension can ~e used without affecting the essential elements of the invention.
The dolly sub-frame remains in its "straight-ahead"
position in which the longitudinal centre lines of the dolly frame and sub-frame are parallel to one another, and moves from that position under control of a centering device comprising a speciallv-shaped cam member 44 fastened to the rear end of the dolly frame.
The cam member provides a vertical cam face 46 consisting of two symmetric mirror-image convex faces meeting at a central concave cusp 48, this cam face cooperating with a cam follower consisting of a roller 50 mounted by a yoke 52 to rotate about a vertical axis 54 the yoke being astened to a transverse bar 56 on the sub-frame. The bar 46 is pivoted at one end to one side-member of the sub-frame about a vertical pivot 58, and has its other end constantly urged in the forward direction by an air-spring 60 interposed between the bar and a bracket 62 on the other side member of the sub-frame. The cam follower roller 50 is therefore constantly urged to maintain it engaged in the cusp 48 at which position the wheels 34 are in a straight-ahead attitude.
The respective mountings of the cam 44 and the cam ~ -follower roller 50 can be reversed, the cam 44 being mounted on the dolly sub-frame 26, while the roller 50 is mounted on the dolly frame 20.
. . " , ~3fl~6 As long as the wheels 34 are running "straiyht-ahead"
they will remain in the corresponding "straight-ahead" or centered position or attitude of Figure X with the cam roller 50 in the cusp ~ .~
48. The centering device in this position provides a positive S cushioned restraining force that will oppose and damp any tendency of the wheels to hunt or oscillate about the centered position.
When the dolly is taken round a curve of sufficiently smal,l radius and the wheels are subjected to a force with a sideways-directed component of grea~er than a predetermined magnitude, then the force of the air spring 60 is overcome and the wheels move from the centered position to an appropriate steering posi~ion, as determined by the internal pressure of the air spring 60 and the cam characteristics of the cam surfaces 46. The wheels will therefore steer around the curve, assuminy for example the attitude illustra~ted hy Figure 2, with consequent reduction in side~ays scrubbing of the whe~ls and wear of their tires and a reduction of the possibility of the rear trailer overturning. However, as soon as the sideways-directed force reduces below the said pre-determine~d value because of their trailing-configuration, the wheels quickly return to the neutral straight-ahead attitude for :
normal straight running, this return being assisted by the urging of the centering device.
When the trailers are to be reversed the dolly frame and sub-frame must be latched together against pivoting motion, and this is effected by a driver-controlled latch constituted by a notched latch plate 88 on the dolly frame 20 that is engaged by a movable latch member 90 on the dolly sub frame 26 while the .
.
:. :
a~6 wheels are in the s-traight-ahead position. The latch member 90 is spring urged to engage the latch and is held in the unlatched position for normal running by a pneumatic motor 92.
It is important that the dolly frame is connected to the rame 64 of the forward trailer in a manner -tha-t will freely permit pitching movement between the two trailers, but tha-t will hold the trailers securely against any relative yawing movement and will also permit only relatively very small rolling movements, since the latter movements could result in instability of the trailer to an extent that overturning or iackknifing occurs. Thus, a certain amount of rolling movement is already accommodated by the fifth wheel connection and the springs 40, so that some rolling movement capability is not ~, disadvantageous. To this end the ~ frame is provided at the respective ends of its two transversely-spaced parallel longitudinal side members with respective vertically-opening loops 66, each of which cooperates with a respective transversely~spaced closable vertically-upwardly opening and extending hook member 68 that hooks into the loop, the hooks being of the type wherein the upwardly-open mouth thereof is closed by a respective latch member 70. Moreover, each hook is provided with a pneumatically-urged plunger 72 operated by a pneumatic motor 74 that is operative while the rig is running to engage the loop 66 and spring press it against the hook inner wall, thereby preventing longitudinal "chatter" movements between the hoop and the loop.
. .
3~6 The two connections therefore permit the required pitching motion by pivoting movement about a horizontal axis, while yawing motion is precluded because of the transverse spacing of the ~wo connections. As described above, only very limited rolling movement is possible or necessary. This particular construction employing a rigid transverse axle permits the ready "retrofit" of -the invention to an existing truck, and also permits the conversion of an exis-ting single draw-bow type fixed wheel dolly to be converted wi~h maximum use of existing components. The dolly of the invention is also suitable for use in a trailer train of more than two trailers e.g. between the second and third -trailer of a "triple train".
Figure 5 illustrates the application of this specific form of connection to my prior transport dolly construction in :15 which the steerable running wheels 34 are mounted on respective king pins 74 connected to the two ends of the axle 32. Each king pin comprises a s,tub axle on which the steerable wheels are mounted and a forwardly-projecting arm 76. the two arms 76 being connected for simultaneous steering movement of the wheels by
~ield of the Invention .
This invention is concerned ~ith improvements in and relating to transport converter dollies of the kind employed for releasable tandem connection of a rearward vehicle to a forward vehicle.
Review of the Prior ~rt The tandem connection toge-ther of two vehicles, particularly a tractor/trailer combination and a second trailer, is of continuing commercial interest, owing to the cost savings that are possible, and accordingly there have been a substantial number of prior proposals disclosing different equipment for this purpose. Despi-te the number of such proposa]s that have been made relatively few such -tandem rigs are in use at this time. A ~undamental problem has been the apparent need hi-~herto to accept either a certain amount of instability in the tandem connection, or else a considerable amount of tire wear with the forward wheels of the rearward vehicle. Thus, it is found that if the dolly is rigidly connected to the frame of the forward trailer, so as to form in effect an extension thereof, the rear trailer being mounted on the dolly by a fifth wheel, then high tire wear is obtained. If the dolly is connected to the forward trailer so as to pivot about a vertical axis the tire wear is reduced, but the presence of two closely~spaced vertical pivots between the two trailers introduces an undesirable instability that has been known to result in -the vehicles overturning or jackknifing.
A self-steering dolly that addresses this problem is described and claimed in our prior Canadian Patent Serial No.
1,108,203, issued 1st September 1981 to Auto Steering Trailers Limited, comprising a dolly frame that is releasably but rigidly connected to the frame of the forward vehicle by which the dolly and the rearward vehicle are to be towed. A fifth wheel connection mounted on the dolly rame releasably receives the front end of the rearward vehicle, and the dolly runs on a pair of road wheels mounted by respective stub axles with link means connecting the stub axles for steering movement about their respective axes under the effect of sideways-directed forces applied to the road wheels by movement of the forward vehicle as it is steered away from a straight line~ Centering means are connected between the link means and the dolly frame and urge the road wheels to a centered straight ahead attitude.
Definition of the Invention .
It is therefore an object of the invention to provide a new transport converter dolly for releasable tandem connection of two vehicles.
It is a more specific object to provide such a dolly which will provide a stable connection between the two vehicIes and yet will minimize the amount of tire wear with the dolly wheels.
.
.~
, 34C~
In accordance with the present invention there is provided a transport for releasable tandem connection of a rearward vehicle to a forward vehicle comprising:
a dolly frame;
means at the forward end of the dolly frame for releasably connecting the dolly frame to the frame of the forward vehicle by which the dolly and the rearward vehicle are to be towed;
the said connecting means comprisng a pair of transversely-spaced connectors attaching the dolly frame to the forward vehicle frame for free pitching movement between the two frames but without substantial rolling or yawing movements between the two frames;
a fifth wheel connection mounted on the dolly frame to releasably receive the front end of the rearward vehicle;
a dolly sub-frame mounted beneath the dolly fra~e by a turntable bearing for steering pivoting rotation about a respecti~e vertical steering pivot axis of the turntable bearing;
a dolly axle;
a spring suspension connected to the dolly sub-frame and the dolly axle and mounting the dolly axle to the dolly sub-frame;
at least two road wheels mounted by the dolly axle and on which the dolly runs; and ~ _ 3 _ . :.
i~
' 43~6 celltering means connected between the dolly fra~lle and the dolly sub-~rame, the centering means permitting pivoting steering movement of the dolly sub-frame and the road wheels about said vertical axis under the effect of sideways-directed forces applied to the road wheels by movement of the forward vehicle as it is steered away from a straight line, and urging the road wheels to a centered straight ahead attitude.
- 3a -~ , ~ ~ ~ 3 ~ 6 The said releasable connecting means may comprise a pair of transversely-spaced, upwardly-opening loop members mounted on one of the frames to extend longitudinally therefrom, and respective transversely-spaced hook members mounted on the other frame so that each hook member hooks into a respective loop member and thereby attaches the dolly frame to the forward vehicle frame for the said free pi-tching mo~ement between the two frames but without substantial rolling or yawing movements between the two frames.
Descriptio~ of the Drawings Self-steering converter dollies which are particular preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein:-FIGURE l is a side elevation showing a tractor/trailer combination and a second trailer e~ploying -the dolly of the invention between the two trailers;
~ IGURE 2 is a plan view from above of a dolly of the invention, showing the centering device employed with -the dolly in an "off-centre" position, the fifth wheel connecting plate being omitted for clarity of illustration, FIGURE 3 is a side elevation of the dolly of Figure 2, the centering device being in the "cen-tered" position, FIGURE 4 is a perspective view to show the part of :
:: :
~34(~6 the dolly connecting means carried by the forward vehicle and its cooperation with the part thereof carried by the dolly, and FIGURE 5 is a plan view of another form of ~olly to show the application of the connecting means of the invention to this s another dolly.
Description of the Preferred Embodimen~s Figure 1 illustrates a typical application of a transport dolly 10 of the in~ention wherein the tractor 12 of a tractor/-trailer combination has the forward trailer 14 coupled thereto via a fifth wheel 16, while a second rear trailer 18 is coupled to ~he forward trailer via the dolly. Referring now more specifically to Figures 2 and 3 the dolly consists of a short rigid rectangular frame 20 having a fifth wheel connecting plate 22 mounted on its upper surface about horizontal pivots Z4. The longitudinal position of the fi~th wheel plate is moved as required for ad~uct-ment of the draw bar weight that is transferred to the forward vehicle. Another short rigid rectangular dolly sub-frame 26 is mounted ~eneath t^~-e frame 20 and is connected thereto by a turn-table bearing 28 for relative rotation about a vertical steering axis 30. A transverse trailing axle 32 carrying running wheels 34 is mounted beneath the su~-frame 26 to th~ rear of the steering axis 30 by any conventional suspension system, which in this embodiment is illustrated as consisting of downward extending hangers 36 and 38 (Figure 2), springs 40 and trailing links 42 to which the axle 32 is clamped. The suspension permits the wheels to move up and down under control of the springs 40 and the usual shock-absorbers (not shown), but constrains them to run parallel to the longitudinal centre-line of the dolly sub-frame as it ~3~
pivots about the a~is 30. In other embodiments other types of suspension can ~e used without affecting the essential elements of the invention.
The dolly sub-frame remains in its "straight-ahead"
position in which the longitudinal centre lines of the dolly frame and sub-frame are parallel to one another, and moves from that position under control of a centering device comprising a speciallv-shaped cam member 44 fastened to the rear end of the dolly frame.
The cam member provides a vertical cam face 46 consisting of two symmetric mirror-image convex faces meeting at a central concave cusp 48, this cam face cooperating with a cam follower consisting of a roller 50 mounted by a yoke 52 to rotate about a vertical axis 54 the yoke being astened to a transverse bar 56 on the sub-frame. The bar 46 is pivoted at one end to one side-member of the sub-frame about a vertical pivot 58, and has its other end constantly urged in the forward direction by an air-spring 60 interposed between the bar and a bracket 62 on the other side member of the sub-frame. The cam follower roller 50 is therefore constantly urged to maintain it engaged in the cusp 48 at which position the wheels 34 are in a straight-ahead attitude.
The respective mountings of the cam 44 and the cam ~ -follower roller 50 can be reversed, the cam 44 being mounted on the dolly sub-frame 26, while the roller 50 is mounted on the dolly frame 20.
. . " , ~3fl~6 As long as the wheels 34 are running "straiyht-ahead"
they will remain in the corresponding "straight-ahead" or centered position or attitude of Figure X with the cam roller 50 in the cusp ~ .~
48. The centering device in this position provides a positive S cushioned restraining force that will oppose and damp any tendency of the wheels to hunt or oscillate about the centered position.
When the dolly is taken round a curve of sufficiently smal,l radius and the wheels are subjected to a force with a sideways-directed component of grea~er than a predetermined magnitude, then the force of the air spring 60 is overcome and the wheels move from the centered position to an appropriate steering posi~ion, as determined by the internal pressure of the air spring 60 and the cam characteristics of the cam surfaces 46. The wheels will therefore steer around the curve, assuminy for example the attitude illustra~ted hy Figure 2, with consequent reduction in side~ays scrubbing of the whe~ls and wear of their tires and a reduction of the possibility of the rear trailer overturning. However, as soon as the sideways-directed force reduces below the said pre-determine~d value because of their trailing-configuration, the wheels quickly return to the neutral straight-ahead attitude for :
normal straight running, this return being assisted by the urging of the centering device.
When the trailers are to be reversed the dolly frame and sub-frame must be latched together against pivoting motion, and this is effected by a driver-controlled latch constituted by a notched latch plate 88 on the dolly frame 20 that is engaged by a movable latch member 90 on the dolly sub frame 26 while the .
.
:. :
a~6 wheels are in the s-traight-ahead position. The latch member 90 is spring urged to engage the latch and is held in the unlatched position for normal running by a pneumatic motor 92.
It is important that the dolly frame is connected to the rame 64 of the forward trailer in a manner -tha-t will freely permit pitching movement between the two trailers, but tha-t will hold the trailers securely against any relative yawing movement and will also permit only relatively very small rolling movements, since the latter movements could result in instability of the trailer to an extent that overturning or iackknifing occurs. Thus, a certain amount of rolling movement is already accommodated by the fifth wheel connection and the springs 40, so that some rolling movement capability is not ~, disadvantageous. To this end the ~ frame is provided at the respective ends of its two transversely-spaced parallel longitudinal side members with respective vertically-opening loops 66, each of which cooperates with a respective transversely~spaced closable vertically-upwardly opening and extending hook member 68 that hooks into the loop, the hooks being of the type wherein the upwardly-open mouth thereof is closed by a respective latch member 70. Moreover, each hook is provided with a pneumatically-urged plunger 72 operated by a pneumatic motor 74 that is operative while the rig is running to engage the loop 66 and spring press it against the hook inner wall, thereby preventing longitudinal "chatter" movements between the hoop and the loop.
. .
3~6 The two connections therefore permit the required pitching motion by pivoting movement about a horizontal axis, while yawing motion is precluded because of the transverse spacing of the ~wo connections. As described above, only very limited rolling movement is possible or necessary. This particular construction employing a rigid transverse axle permits the ready "retrofit" of -the invention to an existing truck, and also permits the conversion of an exis-ting single draw-bow type fixed wheel dolly to be converted wi~h maximum use of existing components. The dolly of the invention is also suitable for use in a trailer train of more than two trailers e.g. between the second and third -trailer of a "triple train".
Figure 5 illustrates the application of this specific form of connection to my prior transport dolly construction in :15 which the steerable running wheels 34 are mounted on respective king pins 74 connected to the two ends of the axle 32. Each king pin comprises a s,tub axle on which the steerable wheels are mounted and a forwardly-projecting arm 76. the two arms 76 being connected for simultaneous steering movement of the wheels by
2~ adjustable-length links 78 and a central T-shaped link member 80. The link member 80 also comprises part of a centering device for this embodiment consisting of a cam member 82 that engages a cam follower 84 on the link member 80 and is urged orwardly in the direction of movement of the dolly by a pneumatic motor 86.
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, .
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, .
3~
In other embodiments which are not illustrated each dolly may include other non-steerable wheels after the steerable wheels for additional load carrying~ The small amount of roll that is to be permitted is that required to accommodate undulations in the road. In embodiments of the kinds illustrated the spacing between the two connectors will usually be about 75-87cm (30-34ins), whlle ~hey will permit vertical movements of about 2.5-5cm (1-2ins), for a consequent maximum roll angle of about 7 degrees.
- 1~ _
In other embodiments which are not illustrated each dolly may include other non-steerable wheels after the steerable wheels for additional load carrying~ The small amount of roll that is to be permitted is that required to accommodate undulations in the road. In embodiments of the kinds illustrated the spacing between the two connectors will usually be about 75-87cm (30-34ins), whlle ~hey will permit vertical movements of about 2.5-5cm (1-2ins), for a consequent maximum roll angle of about 7 degrees.
- 1~ _
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A transport dolly for releasable tandem connection of a rearward vehicle to a forward vehicle comprising:
a dolly frame;
means at the forward end of the dolly frame for releasably connecting the dolly frame to the frame of the forward vehicle by which the dolly and the rearward vehicle are to be towed;
the said connecting means comprising a pair of transversely-spaced connectors attaching the dolly frame to the forward vehicle frame for free pitching movement between the two frames but without substantial rolling or yawing movements between the two frames;
a fifth wheel connection mounted on the dolly frame to releasably receive the front end of the rearward vehicle;
a dolly sub-frame mounted beneath the dolly frame by a turntable bearing for steering pivoting rotation about a respective vertical steering pivot axis of the turntable bearing;
a dolly axle;
a spring suspension connected to the dolly sub-frame and the dolly axle and mounting the dolly axle to the dolly sub-frame;
at least two road wheels mounted by the dolly axle and on which the dolly runs; and centering means connected between the dolly frame and the dolly sub-frame, the centering means permitting pivoting steering movement of the dolly sub-frame and the road wheels about said vertical axis under the effect of sideways-directed forces applied to the road wheels by movement of the forward vehicle as it is steered away from a straight line, and urging the road wheels to a centered straight ahead attitude.
a dolly frame;
means at the forward end of the dolly frame for releasably connecting the dolly frame to the frame of the forward vehicle by which the dolly and the rearward vehicle are to be towed;
the said connecting means comprising a pair of transversely-spaced connectors attaching the dolly frame to the forward vehicle frame for free pitching movement between the two frames but without substantial rolling or yawing movements between the two frames;
a fifth wheel connection mounted on the dolly frame to releasably receive the front end of the rearward vehicle;
a dolly sub-frame mounted beneath the dolly frame by a turntable bearing for steering pivoting rotation about a respective vertical steering pivot axis of the turntable bearing;
a dolly axle;
a spring suspension connected to the dolly sub-frame and the dolly axle and mounting the dolly axle to the dolly sub-frame;
at least two road wheels mounted by the dolly axle and on which the dolly runs; and centering means connected between the dolly frame and the dolly sub-frame, the centering means permitting pivoting steering movement of the dolly sub-frame and the road wheels about said vertical axis under the effect of sideways-directed forces applied to the road wheels by movement of the forward vehicle as it is steered away from a straight line, and urging the road wheels to a centered straight ahead attitude.
2. A transport dolly as claimed in claim 1, wherein the said releasable connecting means comprises a pair of transversely-spaced, upwardly-opening loop members mounted on one of the frames to extend longitudinally therefrom, and respective transversely-spaced hook members mounted on the other frame so that each hook member hooks into a respective loop member and thereby attaches the dolly frame to the forward vehicle frame for the said free pitching movement between the two frames but without substantial rolling or yawing movements between the two frames.
3. A transport dolly as claimed in claim 1, wherein the said releasable connecting means comprises a pair of transversely-spaced, upwardly-opening loop members mounted on the forward end of the dolly frame to extend longitudinally therefrom, and respective transversely-spaced, upwardly-opening hook members mounted on the forward vehicle frame so that each hook member hooks into a respective loop member and thereby attaches the dolly frame to the forward vehicle frame for the said free pitching movement between the two frames but without substantial rolling or yawing movements between the two frames.
4. A transport dolly as claimed in claim 2 or 3, wherein each hook member also comprises a latch member for closing the opening thereof, and a spring-urged plunger engaging a loop member hooked by the hook member to prevent longitudinal chatter between the engaged loop and hook members.
5. A transport dolly as claimed in any one of claims 1 to 3, wherein said centering means comprise a first cam member mounted on one of the dolly frame and the dolly sub-frame and movable therewith, and a second cam member mounted on the other of the dolly frame and the dolly sub-frame and movable therewith, the two cam members cooperating to urge the cam member mounted on the dolly sub-frame to a transverse position corresponding to said centered straight ahead attitude of the steerable road wheels;
and motor means urging one cam member into camming engagement with the other cam member.
and motor means urging one cam member into camming engagement with the other cam member.
6. A transport dolly as claimed in any one of claims 1 to 3, wherein said centering means comprise a first cam member mounted on said dolly frame and movable therewith, the said first cam member comprising a cam having two symmetric mirror-image convex cam faces meeting at a convex cusp which determines the straight-ahead position of the dolly sub-frame and the steerable road wheels, and a second cam member mounted on the dolly sub-frame for movement therewith and also for movement parallel to the direction of movement of the vehicle, the second cam member comprising a cam follower cooperating with the first cam member and engaging the cam faces thereof to urge the first cam member to a transverse position corresponding to said centered straight-ahead attitude of the steerable road wheels; and motor means carried by the dolly sub-frame and urging the cam follower into cam engagement with the cam face of the first cam member.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US30897181A | 1981-10-06 | 1981-10-06 | |
| US308,971 | 1981-10-06 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000423575A Division CA1195357A (en) | 1983-03-14 | 1983-03-14 | Self-steering converter dolly |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1143406A true CA1143406A (en) | 1983-03-22 |
Family
ID=23196109
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000411442A Expired CA1143406A (en) | 1981-10-06 | 1982-09-15 | Self-steering converter dolly |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU557169B2 (en) |
| CA (1) | CA1143406A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6105981A (en) * | 1996-06-24 | 2000-08-22 | Buelt; Kenneth H. | Adjustable steering axle, trailer, and method for operating a trailer |
-
1982
- 1982-09-15 CA CA000411442A patent/CA1143406A/en not_active Expired
- 1982-10-05 AU AU89135/82A patent/AU557169B2/en not_active Ceased
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6105981A (en) * | 1996-06-24 | 2000-08-22 | Buelt; Kenneth H. | Adjustable steering axle, trailer, and method for operating a trailer |
Also Published As
| Publication number | Publication date |
|---|---|
| AU8913582A (en) | 1983-04-14 |
| AU557169B2 (en) | 1986-12-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |