CA1183182A - Dolly for a semitrailer - Google Patents
Dolly for a semitrailerInfo
- Publication number
- CA1183182A CA1183182A CA000416158A CA416158A CA1183182A CA 1183182 A CA1183182 A CA 1183182A CA 000416158 A CA000416158 A CA 000416158A CA 416158 A CA416158 A CA 416158A CA 1183182 A CA1183182 A CA 1183182A
- Authority
- CA
- Canada
- Prior art keywords
- dolly according
- frame
- dolly
- support frame
- coupling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D53/00—Tractor-trailer combinations; Road trains
- B62D53/04—Tractor-trailer combinations; Road trains comprising a vehicle carrying an essential part of the other vehicle's load by having supporting means for the front or rear part of the other vehicle
- B62D53/08—Fifth wheel traction couplings
- B62D53/0857—Auxiliary semi-trailer handling or loading equipment, e.g. ramps, rigs, coupling supports
- B62D53/0864—Dollies for fifth wheel coupling
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Handcart (AREA)
Abstract
"DOLLY FOR A SEMITRAILER"
ABSTRACT OF THE DISCLOSURE
A dolly for use in coupling a semitrailer to the rear of a first semitrailer comprises a coupling frame pro-viding two hitches for attachment to the rear of the first semitrailer and a support frame including road wheels.
The coupling frame is pivotally mounted on a support about a vertical axis so as to allow self-steering movement of the road wheels. A centering device for self-centering the steering comprises a cam carried by the support frame and a cam follower supported on the coupling frame for vertical movement. Air cylinders bias the cam follower to a minimum displacement position centering the steering. The self-centering mechanism is controlled firstly by a device for applying different biasing forces to the cam follower and secondly by a locking device which acts upon manual switch-ing or upon application of the brakes to lock the coupling frame and support frame against steering movement.
ABSTRACT OF THE DISCLOSURE
A dolly for use in coupling a semitrailer to the rear of a first semitrailer comprises a coupling frame pro-viding two hitches for attachment to the rear of the first semitrailer and a support frame including road wheels.
The coupling frame is pivotally mounted on a support about a vertical axis so as to allow self-steering movement of the road wheels. A centering device for self-centering the steering comprises a cam carried by the support frame and a cam follower supported on the coupling frame for vertical movement. Air cylinders bias the cam follower to a minimum displacement position centering the steering. The self-centering mechanism is controlled firstly by a device for applying different biasing forces to the cam follower and secondly by a locking device which acts upon manual switch-ing or upon application of the brakes to lock the coupling frame and support frame against steering movement.
Description
3~
"DOLLY ~OR A SEMITRAILER"
BACKGROUN~ OF THE INVENTION
This invention relates to a dolly for a semi-trailer particularly suitable for attachment to the rear of a Eirst semitrailer so that a second semitrailer can be moved by the same tractor unit. In recent years various appara-tus have been proposed Eor increasing the payloacl towed by a single tractor unit while keeping within legal restric-tions on axle weights. Proposals have been made and carr-ied into practice for towing one or more pup trailers be-ind the main t,railer. Each pup trailer comprises a rear axle and a front steerable axle coupled to a hitch for attachment to the preceding trailer. Thus the pup trailer follows the rear axle of the preceding trailer.
SUMMAR~ OF THE INVENTION
It is one o-bject of this invention to provide a dolly for a semitrailer which can be used to attach a second semitrailer to the rear of a first semitrailer tow-ed by a single tractor unit.
Accordingly the invention provides a dolly for a semitrailer comprising a coupling frame including a first and a second hitch means lying on respective sides of an axis central of the coupling frame for hitching the coupling frame to a prime mover, a fifth wheel arrangement, the vertical axis of which passes through the central axis, mounted on the coupling frarne for receiving the king pin of ~ ! 9~
.,,~, ~ 2-the semitraller, a plurality of road wheels, a support frame mounted on the road wheels, means mounting the coupl-ing frame on the support f-came for pivotal movement rela-tive thereto about a vertical axis passing through the central axis, centering means for biasing the support frame relative to the coupling frame toward a central position in which the road wheels lie parallel to the central axis and means for controlling the centering means.
It is one advantage of the invention therefore that a second semitrailer can be attached to the rear of a first semitrailer by the dolly of the invention and tow-ed in a safe secure manner.
It is a further advantage of the învention that the self-steering effect of the dolly is properly control-led so that the steering of the dolly properly follows the movement of the trailer to which it is attached during normal travel and also resistant to uncontrolled movements or jack-knifing during braking, reversing or traveling over rough terrain.
It is a yet further advantage of the present in-vention that the dolly incorporates control means for the self-steering which is simple, rugged and readily manually adjustable.
With the foregoing in view, and other advantages as will becorne apparent to those skilled in the art to which this invention relates as this specification proceeds, the ~ ~ .
3...L~3~
invention is herein describecl by reference to the accompany-ing drawings forming a part hereof, which includes a de-scription of the best mode known to the applicant and of the preferred typical embodiment of the principles of the pre-sent invention, in which:
~3~
DESCRIPTION OF THE l)RAWINGS
~ ___ _ Figure 1 is a schematic side elevation of a truck including a tractor, semitrailer, the dolly of the inven-tion and a further semitrailer.
Figure 2 is a side elevation of the dolly of Figure 1.
Figure 3 is a section along the line 3-3 of Figure 2.
Figure 4 is a plan view of the front end portions of the side arms of the dolly showing the two hitches.
Figure 5 is a plan view of the rear portion of the dolly showing the rotation locking device.
In the drawings like characters of reference in-dicate corresponding parts of the different figures.
DETAILED DESCRIPTION
-Referring firstly to Figure 1 the mode of use of the dolly of the present invention is shown in schematic form in a truck comprising a tractor unit 10, a convention-al semitrailer 11, the dolly of the invention indicated generally at 12 and a further conventional semitrailer 13.
The semitrailers 11 and 13 are supported at their forward end on conventional fifth wheel arrangements indicated gen-erally at 14, 15 and provided respectively on the tractor unit 10 and on the dolly 12. As shown in more detail herein-after, the dolly 12 is coupled to the rear of the semitrailer 11 by a twin hitch arrangement so that it follows the mo-,~, tion of the semitrailer 11 without pivoting movement about a vertical axis at the coupling between the dolly and the semitrailer 11. For this reason the road wheels of the dolly 12 are coupled to the frame of the dolly in such a way as to allow steering rnovement of the wheels relative to the frame as described in detail hereinafter.
Referring now to Figures 2 and 3, the dolly is shown in detail and comprises a coupling Erame generally indicated at 16 and a support frame generally indicated at 20. The coupling frame 16 comprises a pair of side arms 161, 162 formed of box section steel coupled by cross members 163 indicated in dotted line in Figures 2 similarly formed of box section steel and lying at right angles to the side arms so as to form a rigid structure lying generally in a horizontal plane. Each of the side arms supports adjacent its rear end a right angled flange 164, 165 which is rigid-ly connected to the respective side arm and supports trun-nions 166, 167 for receiving pivot pins 168 of a convention-al fifth wheel arrangement 169 which is pivotal about a horizontal axis lying across the dolly so as to receive and support the forward end of a conventional semitrailer.
A liftable castor wheel 170 is mounted on the side arm 161 in conventional manner to allow the dolly to stand when not in use and to provide height adjustment so that the dolly can be coupled when required to hitches for use.
The structure of the castor wheel, which is shown in ." l ~3~
Figure 2, is conventional and hence no description will be made here.
At the forward end, each side arm 161, 162 car-ries an end plate 171, 172 which is welded across the end of the box section so as to close the box section and form a rigid anchor thereto. A hitch device 173, 17~ is con-nected to each of the end plates by suitable means such as bolts or welding and each comprises a steel ring of rigid structure integral with a coupling plate by which the ring is coupled to the end 171, 172 so that the ring lies in a horizontal plane. Such hitching rings are conventional and are used to hitch the dolly at two spaced locations to a prime mover which as shown in Figure 1 is the rear of the forward semitrailer ll. I'he rings, as is well known, are placed in a yoke 111 which has openings so that a pin can pass through the yoke and through the opening in the ring to provide a coupling which prevents pivotal movement about a vertical axis but allows some movement of the frame 16 about a horizontal axis so as to accommodate any changes in the road surfaces.
The support frame 20 comprises a rectangular frame section 201 formed of side members and cross members details of wnich are not shown and a top plate 202 thus forming a rigid structure with an upper platform. The frame section 201 is supported by conventional road springs 203, 20~ on an axle and road wheels generally indicated at ~ ~33 205. Mounted on top of the platform 202 of the support Erame 20 is a conventional slewing ring assembly 19 which in turn is coupled to the underside of the coupling frame 16. Thus the support frame 20 is coup]ed to the coupling frame 16 by a bearing arrangement which allows the support 20 to pivot relative to the coupLing frame about a verti-cal axis. Referring to Figure 3 it will be noted that the apparatus is substantially symmetrical about a central axis lying parallel to and between the side arms 161, 162 and thus the pivot axis of the coupling between the coupling frame and the support frame passes through the central axis and also the pivot axis of the king pin of the semitrailer mounted upon the fifth wheel similarly pivots about an axis passing through the central axis. From Figure 2, however ~5 it will be noted that the axis of the axle of the road wheel assembly 205 lies behind the pivot axis of the support frame relative to the coupling frame thus when the vehicle is moving forwardly producing a castoring action which will act to maintain the road wheels parallel to the side arms 161, 162. However it will be appreciated that any tendency for the coupling frame to move sideways as caused by turn-ing of the prime mover to which the coupling frame is at-tached will tend to cause the support frame and axle to pivot to take up the turning movement and thus to steer the wheels relative to the turning movement.
In order to assist the self-centering action of the castor arrangement and to inhibit any wobbl.e whi.ch may arise there is provided a self-centering device which acts to bias the support frame to a positi.on wherein the road wheels are parallel to the central axis. The self-center-ing device is generally indicated at 18 and comprises a cam 181 rigidly attached to the front of the support frame 20 and a cam follower 182 carried by the coupling frame 16.
the cam follower comprises a wheel 183 supported in a yoke 18~ carried upon a shaft 185 which is mounted for sliding movement in a sleeve 192 supported by the cross members 163 of the frame 16 so as to allow displacement of the wheel 183 in a vertical direction. As shown more clearly in Figure 3, the cam has a minimum displacement position at the center corresponding to the position where the road wheels lie parallel to the central axis with ramps on either side of the central position so that as the support frame turns relative to the coupling frame to turn the road wheels the cam follower 182 is displaced vertically upwardly by the ramps of the cam 181. Two plates 186 pass through a slot in the shaft 185 to form arms extending either side of the shaft. At the extremi.ty of each arm is coupled a respective one of a pair of pistons 187, 188 of a pair of air cylinders 189, 190. The air cylinders act to apply biasing force to the shaft 185 via the pistons 187, 188 thus tending to cen-ter the cam 181 and return the road wheels to the parallel position.
~ 3 Alr pressure to the cylinders 189, 190 is supplied from the tractor unit 10 via a control device schematically indicated in Figure 2 at 193. The control device 193 in-cludes a lever 194 which controls a valve within the con-trol device 193 (not shown) which acts to control the level of air pressure supplied to the cylinders at 189, 190.
The lever 194 is specifically movable between two positions which have adjustable preset pressure values, one of the positions providing a first pressure within the cylinders 189, 190 which is suitable for use when the trailer carried by the dolly is empty. The second position of the lever 194 provides a pressure which is suitable for use when the trailer supported by the dolly is fully laden. The lever 194 is thus operable by the driver of the vehicle following load-ing the trailer or unloading the trailer and before setting off on the journey. Thus the amount of force applied when the trailer is fully laden is substantially greater than the force supplied when the trailer is empty. In this way the degree of self-centering is compensated for the increased frictional forces involved when a full load is applied to the road wheel assembly. If desired the amount of control over the pressure can be increased from the simple two posi-tion switch to a more complex arrangement providing further levels of control but this has not been found necessary in practice and hence the most simple arrangement has been provided for reducing the complexity to the operator while 1~.
_9_ maintaining the degree of self-centering within acceptable bounds~
~ further control device for the self-centering is shown at the rear of the dolly in Figure 2 and also in S plan view in Figure 5. The cont-rol device comprises a third air cylinder to 2]0, mounted upon an extension brac-ket, extending from the frame 16 so that the air cylinder 210 sits within the frame without extending above the frame to sufficient extent to interfere with the fifth wheel arrangement 169. The air cylinders 210 includes a piston 211 carrying a pin 212 for cooperation with a plurality of slots 213 carried in an arcuate member 214 supported upon the support frame 20 at the rear thereof. The portion 214 is curved about the axis of the slewing ring 14 so that as the support 20 moves relative to the coupling frame 16 the slots 213 of the member 214 move around under the pin 212.
The cylinder 210 is attached via a further control device schematically indicated at 215 to the braking system of the truck. The control device 215 is arranged so that in normal forward traveling, when the brakes of the truck are applied to the wheels to slow or halt the vehicle, pressure is also applied to the cylinder 210 thus moving the pin 212 verti-cally downwardly to enter one of the slots 213. The pin 212 and the member 214 thus cooperate to lock the support frame 20 against rotation movement relative to the coupl~
ing frame 16 so that the road wheel assembly is maintained r ?
, ` ~
33~
in the orientation immediately prior to the application of the brakes thus preventing ~macceptable wobbling and jack-knifing of the dolly during brake application. The control means 215 also includes a lever 216 which can be moved from a first normal position described above wherein air pres-sure is only applied during braking to a second position in which air pressure is continually applied thus locking the support frame 20 relative to the coupling frame 16.
The lever 216 is operable by the driver on leaving his cab and is used for locking the dolly against rotation when re-versing the vehicle or on other occasions, such as when go-ing over rough terrain, when the driver considers it de-sirable to do so.
It will be appreciated therefore that the steer-ing function of the dolly is normally centered by the cas-toring effect achieved by the off set of the relative a~es of the axle and the slewing ring. The control of this cas-toring effect is supplemented by the force from the self-centering cam and cam follower arrangement 18 which in turn can be controlled to apply two or more different forces de-pending upon the load applied to the dolly or other criteria at the discretion of the operator. Furthermore, the self-centering aspect can be locked to cease its action during braking of the vehicle or when otherwise necessary for example during reversing. The dolly is therefore fully con-trolled thus providing a means of supporting a further semi-:" ~ .
3~
trailer in a safe and convenient manner.
Since vaious modi:Eications can be made in my in-vention as hereinabove describecl, and many apparently wide-ly dif:Eerent embodiments of same made withi.n the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the ac-companying specification shall be interpreted as illustra-tive only and not in a limiting sense.
"DOLLY ~OR A SEMITRAILER"
BACKGROUN~ OF THE INVENTION
This invention relates to a dolly for a semi-trailer particularly suitable for attachment to the rear of a Eirst semitrailer so that a second semitrailer can be moved by the same tractor unit. In recent years various appara-tus have been proposed Eor increasing the payloacl towed by a single tractor unit while keeping within legal restric-tions on axle weights. Proposals have been made and carr-ied into practice for towing one or more pup trailers be-ind the main t,railer. Each pup trailer comprises a rear axle and a front steerable axle coupled to a hitch for attachment to the preceding trailer. Thus the pup trailer follows the rear axle of the preceding trailer.
SUMMAR~ OF THE INVENTION
It is one o-bject of this invention to provide a dolly for a semitrailer which can be used to attach a second semitrailer to the rear of a first semitrailer tow-ed by a single tractor unit.
Accordingly the invention provides a dolly for a semitrailer comprising a coupling frame including a first and a second hitch means lying on respective sides of an axis central of the coupling frame for hitching the coupling frame to a prime mover, a fifth wheel arrangement, the vertical axis of which passes through the central axis, mounted on the coupling frarne for receiving the king pin of ~ ! 9~
.,,~, ~ 2-the semitraller, a plurality of road wheels, a support frame mounted on the road wheels, means mounting the coupl-ing frame on the support f-came for pivotal movement rela-tive thereto about a vertical axis passing through the central axis, centering means for biasing the support frame relative to the coupling frame toward a central position in which the road wheels lie parallel to the central axis and means for controlling the centering means.
It is one advantage of the invention therefore that a second semitrailer can be attached to the rear of a first semitrailer by the dolly of the invention and tow-ed in a safe secure manner.
It is a further advantage of the învention that the self-steering effect of the dolly is properly control-led so that the steering of the dolly properly follows the movement of the trailer to which it is attached during normal travel and also resistant to uncontrolled movements or jack-knifing during braking, reversing or traveling over rough terrain.
It is a yet further advantage of the present in-vention that the dolly incorporates control means for the self-steering which is simple, rugged and readily manually adjustable.
With the foregoing in view, and other advantages as will becorne apparent to those skilled in the art to which this invention relates as this specification proceeds, the ~ ~ .
3...L~3~
invention is herein describecl by reference to the accompany-ing drawings forming a part hereof, which includes a de-scription of the best mode known to the applicant and of the preferred typical embodiment of the principles of the pre-sent invention, in which:
~3~
DESCRIPTION OF THE l)RAWINGS
~ ___ _ Figure 1 is a schematic side elevation of a truck including a tractor, semitrailer, the dolly of the inven-tion and a further semitrailer.
Figure 2 is a side elevation of the dolly of Figure 1.
Figure 3 is a section along the line 3-3 of Figure 2.
Figure 4 is a plan view of the front end portions of the side arms of the dolly showing the two hitches.
Figure 5 is a plan view of the rear portion of the dolly showing the rotation locking device.
In the drawings like characters of reference in-dicate corresponding parts of the different figures.
DETAILED DESCRIPTION
-Referring firstly to Figure 1 the mode of use of the dolly of the present invention is shown in schematic form in a truck comprising a tractor unit 10, a convention-al semitrailer 11, the dolly of the invention indicated generally at 12 and a further conventional semitrailer 13.
The semitrailers 11 and 13 are supported at their forward end on conventional fifth wheel arrangements indicated gen-erally at 14, 15 and provided respectively on the tractor unit 10 and on the dolly 12. As shown in more detail herein-after, the dolly 12 is coupled to the rear of the semitrailer 11 by a twin hitch arrangement so that it follows the mo-,~, tion of the semitrailer 11 without pivoting movement about a vertical axis at the coupling between the dolly and the semitrailer 11. For this reason the road wheels of the dolly 12 are coupled to the frame of the dolly in such a way as to allow steering rnovement of the wheels relative to the frame as described in detail hereinafter.
Referring now to Figures 2 and 3, the dolly is shown in detail and comprises a coupling Erame generally indicated at 16 and a support frame generally indicated at 20. The coupling frame 16 comprises a pair of side arms 161, 162 formed of box section steel coupled by cross members 163 indicated in dotted line in Figures 2 similarly formed of box section steel and lying at right angles to the side arms so as to form a rigid structure lying generally in a horizontal plane. Each of the side arms supports adjacent its rear end a right angled flange 164, 165 which is rigid-ly connected to the respective side arm and supports trun-nions 166, 167 for receiving pivot pins 168 of a convention-al fifth wheel arrangement 169 which is pivotal about a horizontal axis lying across the dolly so as to receive and support the forward end of a conventional semitrailer.
A liftable castor wheel 170 is mounted on the side arm 161 in conventional manner to allow the dolly to stand when not in use and to provide height adjustment so that the dolly can be coupled when required to hitches for use.
The structure of the castor wheel, which is shown in ." l ~3~
Figure 2, is conventional and hence no description will be made here.
At the forward end, each side arm 161, 162 car-ries an end plate 171, 172 which is welded across the end of the box section so as to close the box section and form a rigid anchor thereto. A hitch device 173, 17~ is con-nected to each of the end plates by suitable means such as bolts or welding and each comprises a steel ring of rigid structure integral with a coupling plate by which the ring is coupled to the end 171, 172 so that the ring lies in a horizontal plane. Such hitching rings are conventional and are used to hitch the dolly at two spaced locations to a prime mover which as shown in Figure 1 is the rear of the forward semitrailer ll. I'he rings, as is well known, are placed in a yoke 111 which has openings so that a pin can pass through the yoke and through the opening in the ring to provide a coupling which prevents pivotal movement about a vertical axis but allows some movement of the frame 16 about a horizontal axis so as to accommodate any changes in the road surfaces.
The support frame 20 comprises a rectangular frame section 201 formed of side members and cross members details of wnich are not shown and a top plate 202 thus forming a rigid structure with an upper platform. The frame section 201 is supported by conventional road springs 203, 20~ on an axle and road wheels generally indicated at ~ ~33 205. Mounted on top of the platform 202 of the support Erame 20 is a conventional slewing ring assembly 19 which in turn is coupled to the underside of the coupling frame 16. Thus the support frame 20 is coup]ed to the coupling frame 16 by a bearing arrangement which allows the support 20 to pivot relative to the coupLing frame about a verti-cal axis. Referring to Figure 3 it will be noted that the apparatus is substantially symmetrical about a central axis lying parallel to and between the side arms 161, 162 and thus the pivot axis of the coupling between the coupling frame and the support frame passes through the central axis and also the pivot axis of the king pin of the semitrailer mounted upon the fifth wheel similarly pivots about an axis passing through the central axis. From Figure 2, however ~5 it will be noted that the axis of the axle of the road wheel assembly 205 lies behind the pivot axis of the support frame relative to the coupling frame thus when the vehicle is moving forwardly producing a castoring action which will act to maintain the road wheels parallel to the side arms 161, 162. However it will be appreciated that any tendency for the coupling frame to move sideways as caused by turn-ing of the prime mover to which the coupling frame is at-tached will tend to cause the support frame and axle to pivot to take up the turning movement and thus to steer the wheels relative to the turning movement.
In order to assist the self-centering action of the castor arrangement and to inhibit any wobbl.e whi.ch may arise there is provided a self-centering device which acts to bias the support frame to a positi.on wherein the road wheels are parallel to the central axis. The self-center-ing device is generally indicated at 18 and comprises a cam 181 rigidly attached to the front of the support frame 20 and a cam follower 182 carried by the coupling frame 16.
the cam follower comprises a wheel 183 supported in a yoke 18~ carried upon a shaft 185 which is mounted for sliding movement in a sleeve 192 supported by the cross members 163 of the frame 16 so as to allow displacement of the wheel 183 in a vertical direction. As shown more clearly in Figure 3, the cam has a minimum displacement position at the center corresponding to the position where the road wheels lie parallel to the central axis with ramps on either side of the central position so that as the support frame turns relative to the coupling frame to turn the road wheels the cam follower 182 is displaced vertically upwardly by the ramps of the cam 181. Two plates 186 pass through a slot in the shaft 185 to form arms extending either side of the shaft. At the extremi.ty of each arm is coupled a respective one of a pair of pistons 187, 188 of a pair of air cylinders 189, 190. The air cylinders act to apply biasing force to the shaft 185 via the pistons 187, 188 thus tending to cen-ter the cam 181 and return the road wheels to the parallel position.
~ 3 Alr pressure to the cylinders 189, 190 is supplied from the tractor unit 10 via a control device schematically indicated in Figure 2 at 193. The control device 193 in-cludes a lever 194 which controls a valve within the con-trol device 193 (not shown) which acts to control the level of air pressure supplied to the cylinders at 189, 190.
The lever 194 is specifically movable between two positions which have adjustable preset pressure values, one of the positions providing a first pressure within the cylinders 189, 190 which is suitable for use when the trailer carried by the dolly is empty. The second position of the lever 194 provides a pressure which is suitable for use when the trailer supported by the dolly is fully laden. The lever 194 is thus operable by the driver of the vehicle following load-ing the trailer or unloading the trailer and before setting off on the journey. Thus the amount of force applied when the trailer is fully laden is substantially greater than the force supplied when the trailer is empty. In this way the degree of self-centering is compensated for the increased frictional forces involved when a full load is applied to the road wheel assembly. If desired the amount of control over the pressure can be increased from the simple two posi-tion switch to a more complex arrangement providing further levels of control but this has not been found necessary in practice and hence the most simple arrangement has been provided for reducing the complexity to the operator while 1~.
_9_ maintaining the degree of self-centering within acceptable bounds~
~ further control device for the self-centering is shown at the rear of the dolly in Figure 2 and also in S plan view in Figure 5. The cont-rol device comprises a third air cylinder to 2]0, mounted upon an extension brac-ket, extending from the frame 16 so that the air cylinder 210 sits within the frame without extending above the frame to sufficient extent to interfere with the fifth wheel arrangement 169. The air cylinders 210 includes a piston 211 carrying a pin 212 for cooperation with a plurality of slots 213 carried in an arcuate member 214 supported upon the support frame 20 at the rear thereof. The portion 214 is curved about the axis of the slewing ring 14 so that as the support 20 moves relative to the coupling frame 16 the slots 213 of the member 214 move around under the pin 212.
The cylinder 210 is attached via a further control device schematically indicated at 215 to the braking system of the truck. The control device 215 is arranged so that in normal forward traveling, when the brakes of the truck are applied to the wheels to slow or halt the vehicle, pressure is also applied to the cylinder 210 thus moving the pin 212 verti-cally downwardly to enter one of the slots 213. The pin 212 and the member 214 thus cooperate to lock the support frame 20 against rotation movement relative to the coupl~
ing frame 16 so that the road wheel assembly is maintained r ?
, ` ~
33~
in the orientation immediately prior to the application of the brakes thus preventing ~macceptable wobbling and jack-knifing of the dolly during brake application. The control means 215 also includes a lever 216 which can be moved from a first normal position described above wherein air pres-sure is only applied during braking to a second position in which air pressure is continually applied thus locking the support frame 20 relative to the coupling frame 16.
The lever 216 is operable by the driver on leaving his cab and is used for locking the dolly against rotation when re-versing the vehicle or on other occasions, such as when go-ing over rough terrain, when the driver considers it de-sirable to do so.
It will be appreciated therefore that the steer-ing function of the dolly is normally centered by the cas-toring effect achieved by the off set of the relative a~es of the axle and the slewing ring. The control of this cas-toring effect is supplemented by the force from the self-centering cam and cam follower arrangement 18 which in turn can be controlled to apply two or more different forces de-pending upon the load applied to the dolly or other criteria at the discretion of the operator. Furthermore, the self-centering aspect can be locked to cease its action during braking of the vehicle or when otherwise necessary for example during reversing. The dolly is therefore fully con-trolled thus providing a means of supporting a further semi-:" ~ .
3~
trailer in a safe and convenient manner.
Since vaious modi:Eications can be made in my in-vention as hereinabove describecl, and many apparently wide-ly dif:Eerent embodiments of same made withi.n the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the ac-companying specification shall be interpreted as illustra-tive only and not in a limiting sense.
Claims
CLAIMS:
(1) A dolly for a semitrailer comprising a coupl-ing frame including a first and a second hitch means lying on respective sides of an axis central of the coupling frame for hitching the coupling frame to a prime mover, a fifth wheel arrangement, the vertical axis of which passes through the central axis, mounted on the coupling frame for receiving the king pin of the semitrailer, a plurality of road wheels, a support frame mounted on the road wheels, means mounting the coupling frame on the support frame for pivotal movement relative thereto about a vertical axis passing through the central axis, centering means for bias-ing the support frame relative to the coupling frame toward a central position in which the road wheels lie parallel to the central axis and means for controlling the centering means.
(2) A dolly according to Claim 1 wherein the coupling frame comprises a pair of arms spaced either side of the central axis and substantially parallel thereto and a plurality of cross arms interconnecting the side arms and lying at right angles thereto.
(3) A dolly according to Claim 2 wherein the cross arms are of box section.
(4) A dolly according to Claim 2 wherein the side arms are of box section.
(5) A dolly according to Claim 2 wherein one of the hitch means is mounted on one of the side arms and the other of the hitch means is mounted on the other of the side arms.
(6) A dolly according to Claim 2 wherein each of the side arms includes an end plate arranged substantial-ly at right angles to the side arm wherein each hitch means is coupled to a respective one of the end plates.
(7) A dolly according to Claim 1 wherein each hitch means comprises a ring arranged to lie in a horizon-tal plane.
(8) A dolly according to Claim 6 wherein each of the rings is attached to an end of a respective one o the side arms.
(9) A dolly according to Claim 1 wherein the centering means comprises a cam mounted on one of the coup-ing frame and the support frame and a follower mounted on the other of the coupling frame and the support frame, the cam being shaped such that the minimum displacement of the follower occurs at the central position.
(10) A dolly according to Claim 9 wherein the cam is mounted on the support frame and the follower is mounted on the coupling frame.
(11) A dolly according to Claim 9 wherein the follower is displacable in a vertical direction.
(12) A dolly according to Claim 9 wherein the control means is connected to the follower to control move-ment of the follower.
(13) A dolly according to Claim 12 wherein the control means comprises air cylinder means and means for applying pressure to the air cylinder means.
(14) A dolly according to Claim 1 wherein the control means includes means for applying a first force to the centering means, means for applying a second force to the centering means greater than the first force and means for switching between said first and said second forces.
(15) A dolly according to Claim 14 wherein the switching means is manually operable.
(16) A dolly according to Claim 14 wherein the control means comprises air cylinder means and means for applying pressure to the air cylinder means.
(17) A dolly according to Claim 1 wherein the control means includes means for locking the coupling frame relative to the support frame to prevent pivotal movement thereof.
(18) A dolly according to Claim 17 including means for coupling the locking means to a braking system of the prime mover whereby the locking means is applied when the braking means is applied to the prime mover.
(19) A dolly according to Claim 17 including manually operable means for applying said locking means.
(20) A dolly according to Claim 17 wherein the locking means comprises means movable with one of the coup-ling frame and the support frame and defining a plurality of slots and pin means movable with the other of the coup-ling frame and the support frame for movement into coopera-tion with one of the slots in dependence upon the relative position of the coupling and the support frame, to lock the coupling frame relative to the support frame.
(21) A dolly according to Claim 20 wherein there is provided air cylinder means for moving said pin means.
(1) A dolly for a semitrailer comprising a coupl-ing frame including a first and a second hitch means lying on respective sides of an axis central of the coupling frame for hitching the coupling frame to a prime mover, a fifth wheel arrangement, the vertical axis of which passes through the central axis, mounted on the coupling frame for receiving the king pin of the semitrailer, a plurality of road wheels, a support frame mounted on the road wheels, means mounting the coupling frame on the support frame for pivotal movement relative thereto about a vertical axis passing through the central axis, centering means for bias-ing the support frame relative to the coupling frame toward a central position in which the road wheels lie parallel to the central axis and means for controlling the centering means.
(2) A dolly according to Claim 1 wherein the coupling frame comprises a pair of arms spaced either side of the central axis and substantially parallel thereto and a plurality of cross arms interconnecting the side arms and lying at right angles thereto.
(3) A dolly according to Claim 2 wherein the cross arms are of box section.
(4) A dolly according to Claim 2 wherein the side arms are of box section.
(5) A dolly according to Claim 2 wherein one of the hitch means is mounted on one of the side arms and the other of the hitch means is mounted on the other of the side arms.
(6) A dolly according to Claim 2 wherein each of the side arms includes an end plate arranged substantial-ly at right angles to the side arm wherein each hitch means is coupled to a respective one of the end plates.
(7) A dolly according to Claim 1 wherein each hitch means comprises a ring arranged to lie in a horizon-tal plane.
(8) A dolly according to Claim 6 wherein each of the rings is attached to an end of a respective one o the side arms.
(9) A dolly according to Claim 1 wherein the centering means comprises a cam mounted on one of the coup-ing frame and the support frame and a follower mounted on the other of the coupling frame and the support frame, the cam being shaped such that the minimum displacement of the follower occurs at the central position.
(10) A dolly according to Claim 9 wherein the cam is mounted on the support frame and the follower is mounted on the coupling frame.
(11) A dolly according to Claim 9 wherein the follower is displacable in a vertical direction.
(12) A dolly according to Claim 9 wherein the control means is connected to the follower to control move-ment of the follower.
(13) A dolly according to Claim 12 wherein the control means comprises air cylinder means and means for applying pressure to the air cylinder means.
(14) A dolly according to Claim 1 wherein the control means includes means for applying a first force to the centering means, means for applying a second force to the centering means greater than the first force and means for switching between said first and said second forces.
(15) A dolly according to Claim 14 wherein the switching means is manually operable.
(16) A dolly according to Claim 14 wherein the control means comprises air cylinder means and means for applying pressure to the air cylinder means.
(17) A dolly according to Claim 1 wherein the control means includes means for locking the coupling frame relative to the support frame to prevent pivotal movement thereof.
(18) A dolly according to Claim 17 including means for coupling the locking means to a braking system of the prime mover whereby the locking means is applied when the braking means is applied to the prime mover.
(19) A dolly according to Claim 17 including manually operable means for applying said locking means.
(20) A dolly according to Claim 17 wherein the locking means comprises means movable with one of the coup-ling frame and the support frame and defining a plurality of slots and pin means movable with the other of the coup-ling frame and the support frame for movement into coopera-tion with one of the slots in dependence upon the relative position of the coupling and the support frame, to lock the coupling frame relative to the support frame.
(21) A dolly according to Claim 20 wherein there is provided air cylinder means for moving said pin means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000416158A CA1183182A (en) | 1982-11-23 | 1982-11-23 | Dolly for a semitrailer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000416158A CA1183182A (en) | 1982-11-23 | 1982-11-23 | Dolly for a semitrailer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1183182A true CA1183182A (en) | 1985-02-26 |
Family
ID=4124001
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000416158A Expired CA1183182A (en) | 1982-11-23 | 1982-11-23 | Dolly for a semitrailer |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1183182A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1897790A1 (en) * | 2006-09-11 | 2008-03-12 | Transport Industry Development Centre B.V. | Device for coupling a towed vehicle to a towing vehicle, as well as a vehicle combination |
-
1982
- 1982-11-23 CA CA000416158A patent/CA1183182A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1897790A1 (en) * | 2006-09-11 | 2008-03-12 | Transport Industry Development Centre B.V. | Device for coupling a towed vehicle to a towing vehicle, as well as a vehicle combination |
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| MKEC | Expiry (correction) | ||
| MKEX | Expiry |