TOWING DEVICE

Abstract: Towing device on a breakdown vehicle, said towing device comprising: a frame (1) attached to the breakdown vehicle; a boom (2) comprising an arm part (2<1>) pivoted by its first end (3) on the frame (a) by means of a first horizontal joint (4), and a vertical part (2<2>) fixedly connected to the arm part, from which the vertical part extends downwards in a substantially vertical direction; a supporting boom (7) connected to the lower end of the vertical part (2<2>), extending substantially rearwards and provided with supporting elements (8<1>, 8<2>) for supporting the vehicle to be towed; and a power means (9) between the frame and the boom. The supporting boom (7) can be fixedly attached by means of the supporting elements (8<1>, 8<2>) to the chassis (B) of the vehicle to be towed, so that the supporting boom and the vehicle to be towed form a continuous rigid assembly.

Description: TOWING DEVICE The present invention relates to a towing de¬ vice as defined m the preamble of claim 1. Previously known is a towmg device which is mounted on a breakdown vehicle for the towmg of an¬ other vehicle. Such a towing device comprises a frame which is fixedly connected to the chassis of a break¬ down vehicle, being fixed e.g. directly to the longi¬ tudinal beams of the chassis of a truck or to auxil- lary frames mounted on them. In some cases, the frame of the towing device may also be fixed to a chassis which is provided with interchangeable platform equip¬ ment and which can be moved onto the chassis of a ve¬ hicle provided with corresponding equipment for moving an interchangeable platform. The prior-art towing de¬ vice further comprises a boom comprising an arm part pivoted by its first end on the frame of the towing device by means of a first horizontal joint, whose joint axis lies substantially in a horizontal direc- tion transverse to the longitudinal direction of the breakdown vehicle, and a vertical part fixedly con¬ nected to the second end of the arm part, from which the vertical part extends downwards n a substantially vertical direction. Moreover, the towmg device com- prises a supporting boom connected to the lower end of the vertical part, extending substantially rearwards the longitudinal direction of the breakdown vehicle and provided with supporting elements for supporting the vehicle to be towed. In addition, the tow g de- vice comprises a power means arranged to act between the frame and the boom to turn the boom and the sup¬ porting boom about the first horizontal joint axis so that the front or rear end of the vehicle to be towed can be lifted clear of the ground and supported by the boom, permitting the vehicle to be towed by the break¬ down vehicle. A problem with the use of prior-art towing devices is that the point at which the load of the ve¬ hicle being towed is centred on the supporting boom of the breakdown vehicle lies at a fairly long distance from the point of ground support of the rear wheels of the breakdown vehicle, with the result that the mass centre of the vehicle combination of breakdown vehicle and towed vehicle is shifted considerably rearwards and the load of the towed vehicle develops a large torque tending to turn the breakdown vehicle about the point of ground support of its rear wheels and to lift the front wheels of the breakdown vehicle off the ground. For this reason, to ensure that the breakdown vehicle can be driven and steered, it has been neces- sary to mount heavy counterweights on the front end of the breakdown vehicle and/or additional weights mov¬ able the longitudinal direction of the breakdown vehicle on its chassis. These extra counterweights and additional weights, which may have a weight of several tons, significantly reduce the carrying capacity of the breakdown vehicle and require the addition of more axles to the vehicle, which again make the vehicle more expensive and more difficult to steer. The object of the invention is to eliminate the above-mentioned drawbacks. A specific object of the invention is to pre¬ sent a simple, cheap and easy-to-use towing device which allows the breakdown vehicle to be used with ad¬ ditional weights considerably smaller than before or without any additional weights at all without essen¬ tially reducing the controllability or steerability of the breakdown vehicle, making it possible to increase the carrying capacity of the breakdown vehicle and to tow heavier loads with it. The towmg device of the invention is charac¬ terized by what is presented claim 1. According to the mvention, the supporting boom is so designed that it can be fixedly attached by means of supporting elements to the chassis of the ve¬ hicle to be towed so that when the supporting boom has been fixed to a vehicle to be towed, the supporting boom and the vehicle to be towed form a continuous as¬ sembly rigid against downward forces; the towing de¬ vice comprises a vertical joint with a vertical joint axis, disposed in front of the assembly formed by the supporting boom and the vehicle to be towed so that it allows the combination to turn; and the supporting boom is pivoted on the vertical part of the boom with a second horizontal joint so that it can turn freely, the joint axis of said horizontal joint lying substan- tially in a horizontal direction transverse to the longitudinal direction of the vehicle. In other words, the invention is based on the idea that the vehicle to be towed and the supporting boom attached to it form an assembly which is hauled like a semi-trailer after the breakdown vehicle, said assembly being rigid at least against downward forces, this rigidity being en¬ sured e.g. by the weight of the vehicle to be towed, which holds the supporting boom pressed against the vehicle. The invention has the advantage that, due to the joint between the boom and the supporting boom, the load force imposed on the breakdown vehicle by the vehicle being towed always acts in a vertical direc¬ tion, being applied to the joint axis of the second horizontal joint, which is located as close as possi¬ ble to the breakdown vehicle, so the moment arm is considerably shorter than in prior-art solutions. This means that the need for the use of counterweights or additional weights to shift the mass centre forward is reduced or eliminated, thus increasing the available load of the breakdown vehicle. A breakdown vehicle equipped w th a towing device as provided b the m- vention is therefore able to tow heavier vehicles than before. In an embodiment of the towing device, the supporting elements comprise a first supporting ele- ment and a second supporting element, which are dis¬ posed along the length of the supporting boom at a distance from each other; and at least the rearward one of the supporting elements is so designed that it can be fixedly attached to the chassis of the vehicle to be towed. Preferably the first supporting element consists of a supporting surface open at the top, a supporting hook or hooks or an equivalent supporting point, on which the vehicle to be towed is held fast by its own weight. The second supporting element may consist of various chains, belts, cables, clasps, latches, hooks and sockets, slots and grooves and equivalent, which may be provided either in the sup¬ porting boom or in the vehicle to be towed or in both. The essential feature of the second supporting element is that it keeps the supporting boom connected to the towed vehicle against the force exerted by the weight of the vehicle. It is also possible within the frame¬ work of the inventive idea that the supporting ele¬ ments consist of a socket or an equivalent space in the towed vehicle into which the supporting boom is inserted or placed and the second supporting element is a suitable locking device by means of which the supporting boom is locked fast in the socket. The supporting boom is preferably adjustable in length. The supporting boom may be of a construc¬ tion permitting shortening and elongation in a tele¬ scopic manner. By two attachment points located at a distance from each other along the length of the boom, the supporting boom can be attached to the chassis of the vehicle to be towed so that the supporting boom is stiff against downward forces. The telescopic adjust- ment allows the supporting boom to be fitted to dif¬ ferent vehicles to be towed. In an embodiment of the towmg device, the supporting boom comprises a first supporting boom sec- tion, connected with a second horizontal joint to the vertical part of the boom, and a second supporting boom section, connected with a vertical joint to the first supporting boom section. In an embodiment of the towing device, the device comprises a first set of locking elements for locking the vertical joint rigidly in position. The first set of locking elements may consist of mechani¬ cal locking devices, but the locking can also be ef¬ fected using a hydraulic cylinder, which, when re- leased, acts as a damper of the horizontal movement of the supporting boom and it can also be used for turn¬ ing the supporting boom horizontally. In an embodiment of the towmg device, the device comprises a second set of locking elements for locking the second horizontal joint rigidly m posi¬ tion. The second locking element is preferably the same hydraulic cylinder that is normally used to raise and lower the supporting boom between a vertical high position and a horizontal low position. In this case, by releasing the hydraulic cylinder durmg towmg, it functions as a damper of the vertical movement. In an embodiment of the towing device, the power means is a pressurized-medium operated power means, such as a hydraulic cylinder, preferably a sin- gle action hydraulic cylinder. In an embodiment of the towmg device, the boom and/or the supporting boom is constructed of tu¬ bular profiled beams of rectangular cross-section. In an embodiment of the towing device, the rearward second supporting element comprises a bottom support transverse to the supporting boom, designed to support the vehicle to be towed from below, and a de- tachable and attachable flexible tying element con¬ nected to the bottom support, designed to be tied around the chassis or a part of it. In the following, the invention is described in detail by the aid of embodiment examples by refer¬ ring to the attached drawing, in which Fig. 1 presents a diagrammatic side view of an embodiment of the device of the invention, mounted on a breakdown vehicle, as well as a vehicle towed by means of the towmg device, and Fig. 2 presents a perspective view of the em¬ bodiment of the towing device presented in Fig. 1, seen obliquely from above. Figures 1 and 2 show a towing device mounted on a breakdown vehicle for towing another vehicle. The towing device comprises a frame 1 which is fixed to the chassis A of the breakdown vehicle. Moreover, the towing device comprises a boom 2, which is constructed of a tubular profiled beam of rectangular cross- section. The boom 2 comprises an arm part 2 1 , which is pivoted by its first end 3 on the chassis A by means of a first horizontal joint 4, whose joint axis 5 lies substantially in a horizontal direction transverse to the longitudinal direction of the breakdown vehicle. In addition, the boom 2 comprises a vertical part 2 " fixedly connected to the second end 6 of the arm part 2 1 , from which the vertical part 2 " extends downwards in a substantially vertical direction. The supporting boom 7 is connected to the lower end of the vertical part 2 " , extending substantially rearwards the lengthways direction of the breakdown vehicle, the supporting boom 7 being pivoted on the vertical part 2 Z of the boom by means of a second horizontal joint 12, whose joint axis 13 lies a substantially hori- zontal direction transverse to the longitudinal direc¬ tion of the breakdown vehicle. Mounted between the vertical part and the supporting boom is a hydraulic cylinder 15, which also acts as a second locking ele¬ ment, by means of which the second horizontal joint 12 can be locked m a desired position, e.g. to hold the supporting boom in an upright position durmg trans- port or in a horizontal position when the supporting boom is being moved into position under a vehicle to be towed. The supporting boom 7 comprises supporting elements 8 , 8 for supporting the vehicle to be towed. By means of the supporting elements, the supporting boom 7 can be fixedly attached to the chassis B of the vehicle to be towed so that when the supporting boom 7 has been fixed to the vehicle to be towed, the sup¬ porting boom 7 and the vehicle to be towed form a con- tinuous, rigid assembly. Moreover, the towing device comprises a vertical joint 10, whose joint axis 11 lies in a vertical direction and which is disposed in front of the assembly formed by the vehicle to be towed and the supporting boom 7 to allow the combina- tion to turn. The vertical joint 10 is also provided with a first set of locking elements 14 to lock the vertical joint 10 rigidly in position. Disposed between the frame 1 and the boom 2 is a power means 9 for turning the boom 1 and the sup- porting boom 7 about the first horizontal joint 4 to lift the front or rear end of the vehicle to be towed clear of the ground so that its weight is supported by the boom. The power means 9 a pressurized-medium oper¬ ated power means, such as a hydraulic cylinder, pref- erably a single action hydraulic cylinder. The supporting boom 7 comprises a first sup¬ porting boom section 7 , pivoted with the second hori- 2 zontal joint 12 on the vertical part 2 of the boom 2, 2 and a second supporting boom section 7 , pivoted with the vertical joint 10 on the first supporting boom section 7 1. The second supporting boom section 7 π of the supporting boom 7 is of a construction permitting telescopic length adjustment. The supporting boom 7 is composed of tubular profiled beams of rectangular cross-section. The supporting elements 8 1 , 8 2 comprise a first supporting element 8 and a second supporting element 8 which are disposed along the length of the supporting boom 7 at a distance from each other so that the chassis of the vehicle to be towed can be at¬ tached to the supporting boom at two points . The for- ward first supporting element 8" comprises a support designed to support the chassis of the vehicle to be towed from below. The rearward supporting element 8 can be fixedly attached to the chassis B of the vehi¬ cle to be towed. The rearward or second supporting element 8 also comprises a bottom support 16 trans¬ verse to the supporting boom, designed to support the chassis B of the vehicle to be towed from below, and addition a detachable and attachable, flexible ty¬ ing element 17, e.g. a chain, belt or the like, which is connected to the bottom support and which can be tied around the chassis B or a part of it. The invention is not restricted to the exam¬ ples of its embodiments described above, but many variations are possible withm the framework of the inventive idea defined by the claims.

Claims: CLAIMS 1. Towmg device on a breakdown vehicle, de¬ signed for the towmg of another vehicle, said towmg device comprising: a frame (1) attached to the chassis (A) of the breakdown vehicle; a boom (2) comprising an arm part (2 ) piv¬ oted by its first end (3) on the frame (A) by means of a first horizontal joint (4) whose joint axis (5) lies in a substantially horizontal direction transverse to the longitudinal direction of the breakdown vehicle, and a vertical part (2 ) fixedly connected to the sec¬ ond end (6) of the arm part, from which the vertical part extends downwards m a substantially vertical di- rection; a supporting boom (7) connected to the lower end of the vertical part (2 ) , extending substantially rearwards in the longitudinal direction of the break¬ down vehicle and provided with supporting elements (8 1, 82) for supporting the vehicle to be towed; and a power means (9) arranged to act between the frame and the boom to turn the boom and the supporting boom about the joint axis (5) to lift the front or rear end of the vehicle to be towed clear of the ground so that it is supported by the boom, c h a r ¬ a c t e r i z e d that the supporting boom (7) is so designed that it can be fixedly attached by means of the supporting elements (8 , 8 ) to the chassis (B) of the vehicle to be towed, so that when the supporting boom has been fixed to a vehicle to be towed, the supporting boom and the vehicle to be towed form a continuous assembly rigid against downward forces; the towing device comprises a vertical joint (10) whose joint axis (11) is in a vertical direction and which is disposed in front of the rigid assembly formed by the supporting boom and the vehicle to be towed so that it allows the combination to turn; and the supporting boom (7) is pivoted on the vertical part (2 2 ) of the boom with a second horizon- tal joint (12) so that it can turn freely during tow¬ ing, the joint axis (13) of said horizontal joint ly¬ ing in a substantially horizontal direction transverse to the longitudinal direction of the vehicle. 2. Device as defined in claim 1, c h a r a c - t e r i z e d in that the supporting elements (8 1 , 8 2 ) comprise a first supporting element (8 1 ) and a second supporting element (8 ) arranged along the length of the supporting boom (7) at a distance from each other; and that at least the rearward one of the supporting elements (8 ) is so designed that it can be fixedly attached to the chassis (B) of the vehicle to be towed. 3. Device as defined in claim 1 or 2, c h a r a c t e r i z e d in that the supporting boom (7) comprises a first supporting boom section (7 ), piv¬ oted with the second horizontal joint (12) on the ver¬ tical part (2 ) of the boom (2) , and a second support¬ ing boom section (7 ), pivoted with the vertical joint (10) on the first supporting boom section (7 ) . . Device as defined in any one of claims 1 - 3, c h a r a c t e r i z e d in that the supporting boom (7) is adjustable in length. 5. Device as defined in claim 4, c h a r a c ¬ t e r i z e d in that the supporting boom (7) is of a construction permitting shortening and elongation in a telescopic manner. 6. Device as defined in any one of claims 1 - 5, c h a r a c t e r i z e d in that the device comprises a first set of locking elements (14) for locking the vertical joint (10) rigidly in position. 7. As defined in any one of claims 1 - 6, c h a r a c t e r i z e d in that the device comprises a second set of locking elements (15) for locking the second horizontal joint (12) rigidly in position. 8. As defined in claim 6 or 7, c h a r a c ¬ t e r i z e d in that the locking element (14,15) is a hydraulic cylinder which can be released to permit free movement of the respective joint and locked in a desired position. 9. Device as defined in any one of claims 1 - 8, c h a r a c t e r i z e d in that the boom (2) and/or the supporting boom (7) are constructed of tubular profiled beams of rectangular cross-section. 10. Device as defined in any one of claims 2 - 9, c h a r a c t e r i z e d in that the rearward sec¬ ond supporting element (8 2 ) comprises a bottom support (16) transverse to the supporting boom to support the chassis (B) of the vehicle to be towed from below, and a detachable and attachable flexible tying element (17) connected to the bottom support, to be tied around the chassis (B) or a part of it.

Inventors: VYYRYLAEINEN JUHANI, VYYRYLAEINEN, JUHANI
Applicants: KOUVOLAN SUN FILTER OY, VYYRYLAEINEN JUHANI, KOUVOLAN SUN-FILTER OY, VYYRYLAEINEN, JUHANI
Application year: 1996
Main classification: B60P3
IPC codes: B60D1, B60P3