WO1990006240A1

WO1990006240A1 - Traction device

Info

Publication number: WO1990006240A1
Application number: PCT/SE1989/000691
Authority: WO
Inventors: Göran DEGERFELT
Original assignee: Industri- Och Transportkonsult Ab
Priority date: 1988-11-28
Filing date: 1989-11-27
Publication date: 1990-06-14
Also published as: SE8804298D0; SE8804298A

Abstract

This invention relates to a traction device for vehicles, preferably tractors, and comprising a towing hook arranged at the outer end of a towing bar, which extends in the longitudinal direction of the vehicle and is arranged in a frame of the vehicle, the inner part of the frame being pivotably fastened to the vehicle so that the frame can be pivoted downwards from an upper, in the normal case essentially horizontal position to a lower position. According to the invention the towing bar (6) is extractable and retractable in relation to the frame (1) by means of at least one hydraulic cylinder (7), which extends essentially parallel with the towing bar (6). The towing bar (6) and the frame (1) are held in its upper, essentially horizontal position by means of a first locking device (13, 14), which is so designed that it automatically goes into engagement, when the towing bar and the frame are raised to its upper position. The towing bar (6) can be locked in its inner position in relation to the frame (1) by means of a second locking device (16, 17).

Description

TRACTION DEVICE This invention relates to a traction device for vehicles, preferably tractors, and comprising a towing hook arranged at the outer end of a towing bar, which extends in the longitu- dinal direction of the vehicle and is arranged in a frame of the vehilce, the inner part of the frame being pivotably fastened to the vehicle so that the frame can be pivoted down¬ wards from an upper, in the normal case essentially horizontal position to a lower position. Towing hooks are common in tractors and other vehicles in order that it shall be possible to tow trailers of different kinds by the tractor. These trailers as a rule are so heavy that it is not possible for a person to lift up the towing trailer bar and attach it onto the towing hook of the tractor, but one has as a rule to reverse the tractor towards the trailer so that the towing hook comes adjacent to the loop of the towing trailer bar and then the towing hook of the tractor is inserted into the loop of the trailer bar by means of the hydraulic system of the tractor. Lately this moment has been facilitated_^ somewhat since the frame in which the towing hook has been fastened has been pivotably suspended in relation to the tractor at its inner end and due to that fact has been able to be pivoted from an essentially horizontal position to a lower position. Due to that fact the driver has been able to lower the towing hook in connection with the insertion of the same into the loop of the trailer bar and then to reverse the tractor to the area of the front part of the trailer bar. In this position the tractor driver by means of the hydraulic system of the tractor has raised the towing hook so that it should come into the loop but this moment has rendered diffi¬ cult by the fact that the driver has had a bad view backwards and therefore he has as a rule been able to make many attempts before he has succeeded in getting the towing hook into the loop of the trailer bar. This invention relates to remove the problems with known^' technique. This has been made possible by a traction device of the kind mentioned by way of introduction which is character¬ ized in¹ that the towing bar is extractable and retractable in

, i relatioh to the frame by means of at least one hydraulic cy- linder extending essentially parallel with the towing bar, that the towing bar and the frame are held in its upper, essentially horizontal position by means of a first locking device, which is so designed that it automatically goes into engagement when the towing bar and the frame are raised to their upper posi¬ tion, and that the towing bar can be locked in its inner posi¬ tion in relation to the frame by means of a second locking de¬ vice. Due to that fact the tractor driver when connecting the towing hook with the loop of the trailer bar can push out the towing hook so far that he can see it from his driver's cab, whereafter he reverses the tractor to the area of the front part of the trailer bar. Due to the fact that the driver all the time has the view backwards and accordingly sees the posi¬ tion of the towing hook in relation to the loop of the trailer bar he can reverse the tractor so that the towing hook comes straightly under the loop of the trailer bar. In this position the towing hook is brought upwards by means of the hydraulic system of the tractor and is accordingly inserted into the loop of the trailer bar. Thus, the connection of the towing hook and the loop is made very smoothly and effectively by the new in¬ vention. Furthermore, the towing bar is by the invention locked effectively and smoothly in its upper, essentially horizontal position and in its retracted position by means of a first and a second locking device. A preferred embodiment of the invention shall be de¬ scribed more closely with reference to the accompanying draw¬ ing, in which Fig. 1 shows a horizontal view of a traction device, partly cut up, which is shown in a retractable posi¬ tion, extractable position and a lowered position, and Fig. 2 shows the traction device seen from above, the device being partly cut up so that one hydraulic cylinder can be seen.

•Referring to Fig. 1 is shown there a traction device according to the invention. The traction device comprises a frame 1, which at its inner^' end is pivotably fastened to a shaft 2, which in its turn is fastened to the underside of the chassis of the tractor by means of holders 3, 4. Due to that fact the traction device can be pivoted downwards from an upper position, which is essentially horizontal to a lower position. The frame 1 has a box-formed design with an essentially rectan- gular cross-section.

The traction device further comprises a towing hook, which is arranged at the outer end of a towing bar 6, which is extractable and retractable in relation to the frame 1. In that connection the towing bar 6 is intended to be pushed out of and be pulled into the box-formed frame. The extraction and retrac¬ tion of the towing bar is made by means of two hydraulic cylin¬ ders (see Fig. 2) of which only one 7 of them is shown in the figure. In that connection the one cylinder is positioned on the one side of the towing bar and parallel with this one while the second cylinder is positioned parallel with the towing bar on its other side. The hydraulic cylinders are fastened to the frame 1 in a suitable way.

A plunger 8, 9 is by means of the hydraulic system of the tractor hydraulically extractable out of and retractable into respective cylinder 7. In that connection the outer ends 10, 11 of the plungers are fastened to each end of a transverse shaft 12 which goes through the towing bar 6 at its outer part.

Of course, it is possible instead of having two hydraulic cylinders controlling the extraction out of and the retraction into the frame to have only one hydraulic cylinder. It is also possible that the control of the towing bar is made in a mecha¬ nical way, for instance by a screw device. This screw device should be able to be driven by means of a small electric motor or a hydraulic motor.

The towing bar 6 and the frame 1 are hold in place in an essentially horizontal position, when the tractor is in an essentially horizontal position, under the chassis of the trac¬ tor by means of a first locking device comprising two hooks of which only one 13 is shown in the drawing. Each of these two hooks cooperates with a projection, of which only one 14 is shown in the drawing, which projections are arranged at the outer part of the frame on each side of the longitudinal centre line of the frame. The hooks 13 are intended to go into engage- ment with the projections 14 automatically when the towing bar and the frame have been raised to the horizontal position, which shall be taken when the tractor shall tow the trailer. Moreover, before that the towing bar shall be entirely retrac¬ ted into the frame. In order that the towing bar shall be able to be hold in that position there is a second locking device comprising a spring-loaded pin 16 which is intended to engage into a hole 17 which is made on the top side of the towing bar at its outer part. In Fig. 1 this retracted position is indi- cated by continuous lines. This pin 16 is fastened to the chassis of the tractor at the area of the outer part of the frame and can bring about a movement in the vertical plane, that is in a plane which is essentially perpendicular to the longitudinal direction of the towing bar 6 when this one has taken its upper position. The pin 16 is suitably circular-cy- lindrically designed and is guided in a sleeve 18.

The device functions in the following way when connecting a trailer to a tractor:

The tractor driver begins with loosening the hooks 13 from the projections 14 in a hydraulic or mechanical way, whereafter the towing bar and the frame are pivoted downwards by means of the hydraulic system of the tractor. Due to that fact the engagement between the pin 16 and the hole 17 is dis¬ continued. At the same time the towing bar is pushed out of the frame by means of the hydraulic cylinders 7 to a position where the tractor driver can see the towing hook 5. Thereafter the tractor driver reverses the tractor backwards until its towing hook comes essentially straightly under the loop trailer bar. This operation becomes very simple to do by this invention, since the driver all the time keeps a view over the position for the towing hook in relation to the loop. When the towing hook has come to the right position, the towing bar and the frame are raised until the hooks 13 automatically have taken the position round the projections 14. When that has happened the towing bar is pulled into the frame by means of the hydrau¬ lic cylinders 7 until the spring-loaded pin 16, which up to now has slided on the upper side of the bar, snaps into the hole 17 in the towing bar. In this position, the towing hook 5 cooper¬ ates with a projection 20 which is arranged in the outer por- tion of the frame, whereby the loop of the trailer cannot come loose. In order to facilitate the control during the movement of the towing bar out of and into the frame, a sleeve 21 may be arranged in the frame in which the towing bar slides.

In the patent application has been talked about "outer" and "inner" part regarding the towing bar and the frame. These two means as appears from the application are intended to be placed in the back part of the vehicle. With "outer" is accord¬ ingly meant the back part of the means, while the inner part of the means accordingly comprises the front part, that is that part of the means which is positioned closest to the front portion of the vehicle.

Of course, the invention is not limited to the mentioned embodiment but can be modified within the scope of the follow- ing claims.

Claims

Claims 1. A traction device for vehicles, preferably tractors, and comprising a towing hook arranged at the outer end of a towing bar, which extends in the longitudinal direction of the vehicle and is arranged in a frame of the vehicle, the inner part of the frame being pivotably fastened to the vehicle so that the frame can be pivoted downwards from an upper, in the normal case essentially horizontal position to a lower posi¬ tion, c h a r a c t e r i z e d in that the towing bar (6) is extractable and retractable in relation to the frame (1) by means of at least one hydraulic cylinder (7) , which extends essentially parallel with the towing bar (6) , that the towing bar (6) and the frame (1) are hold in its upper, essentially horizontal position by means of a first locking device (13, 14) , which is so designed that it automatically goes into en¬ gagement, when the towing bar and the frame are raised to its upper position, and that the towing bar (6) can be locked in its inner position in relation to the frame (1) by means of a second locking device (16, 17).

2. A device according to claim 1, c h a r a. c t e r — i z e d in that the first locking device comprises two hooks (13) , which are intended to cooperate with two projections (14) , arranged at the outer part of the frame (1) on each side of the longitudinal centre line of the frame (1) , that the hooks (13) automatically go into engagement round the projec¬ tions (14) when raising the towing bar and the frame to the upper position, and that the hooks (13) during disengagement are intended to be hydraulically or mechanically operated from the driver's place in the tractor.

3. A device according to claim 1 or 2, c h a r a c ¬ t e r i z e d in that the second locking device comprises a pin (16) which is fastened into the chassis of the vehicle and is intended to cooperate with a hole (17) on the towing bar (6).

4. A device according to claim 3, c h a r a c t e r ¬ i z e d in that the hole (17) is arranged at the outer part of the towing bar (6) on its top side, and that the pin (16) is fastened in the chassis of the vehicle at the area of the outer portion of the frame and is intended to perform a movement in the vertical plane, that is a plane which is essentially perpendicular to the longitudinal direction of the towing bar, when this one has taken its upper position.

5. A device according to any one of the preceding claims, c h a r a c t e r i z e d in that the movements of the towing bar (6) in relation to the frame are made by means of two hydraulic cylinders (7) , each of which is provided with a plunger (8, 9), which are extractable out of and retractable into the hydraulic cylinders (7) , and that the outer end (10, 11) of the plungers is fastened in each end of a transverse bar, which goes through the towing bar (6) at its outer part.

6. A device according to any one of the preceding claims, c h a r a c t e r i z e d in that the frame (1) is box-formed designed and has essentially a rectangular cross-section, and that the inner part of the frame is pivotably fastened to a shaft (2) which in its turn is fastened under the chassis of the vehicle by means of holders (3, 4).