STEERING FOR THE SWIVEL-SUPPORTED WHEELS OF A TRAILER

Abstract: A vehicle, such as a trailer or semi-trailer (2), suitable to be coupled with a tractor (1), said vehicle (2) having one or more supporting axles with at the ends of at least one axle swivel-supported, steered wheels (5,6,40,41,42,43) each of said wheels being connected to a swivel body (38,39,44,45), each swivel body is connected to a swivel arm (36,37,46,47) which is controlled by a steering rod (22,23,54,55) via a lever transmission (26,27,32,33,48,49,50,51). Said steering rod (22,23,54,55) is connected to the one arm (16,17) of a cranck lever (14,16; 15,17), the fulcrum (18,19) of which is pivotally supported by the vehicle (2). The other arm (14,15) of said lever (14,16; 15,17) is carrying a follower (12,13) which is located in a guiding path (10,11) of a curve plate (7) being pivotally supported by the vehicle (2) and being secured against pivoting with respect to the tractor (1) on coupling of the vehicle (2) with the tractor (1).

Description: The invention relates to a vehicle, such as a trailer or semi-trailer, suitable to be coupled with a tractor, said vehicle having one or more supporting axles with at the ends of at least one axle swivel-supported, steered wheels, a rod system being provided controlling a steering arm, connected with a swivel body for steering the relevant wheel. Such a vehicle is known from the Belgian patent specification Nr. 459,795. According to this patent specification use is made of a four-armed lever which is pivotably and movably mounted and is connected to two steering rods being connected with another lever which in its turn is pivoted by means of an arm being coupled with a chain wheel. A chain is passing over said chain wheel and another chain wheel which is rotated if the trailer of semi-trailer turns with respect to the tractor. This brings along a complicated and thus expensive construction. Also tolerance may occur at many positions and in particular the chain may be streched so that the swivel supported wheels will no longer assume their proper position. The invention has as an object to overcome these disad­ vantages and provides to that purpose that a steering arm is controlled by a steering rod via a lever transmission, said steering rod extending substantially parallel with the longitudinal centre line of the vehicle and being connected to the one arm of a cranck lever, the fulcrum of said lever being pivotally supported by the vehicle, the other arm of said lever carrying a follower which is located in a guiding path of a curve plate being pivotally supported by the vehicle and being secured against pivoting with respect to the tractor on coupling of the vehicle with the tractor. In this way a particularly simple construction is obtained, by which construction the steering of a wheel can take place very accurately by a proper design of the curve plate. Though the wheels of one supporting axle may be mutually connected in the known way by means of coupling levers and a track rod, it will particularly being provided that the swivel arms of the wheels at both ends of an axle each are controlled by a steering rod and relating cranck lever, the follower of both cranck levers cooperating with one single guiding path incorporated in the curve plate. By this it can be guaranteed that also in case of failure of one cranck lever, of a steering rod or any other part, stillboth wheels are steered. In particular in case of large heavy vehicles the safety is considerably increased. Because of said double execution of the steering device the stability of said system is substantially increased. It is now possible to take care that the followers of the cranck levers which are located in the guiding path of the curve plate always engage the outer or the inner side of said guide path. By this shimmy of the wheels is prevented. According to a preferred embodiment of the invention a swivel arm will be directed substantially towards the longitudinal centre plane of the vehicle and the end of this will be connected to one end of a double armed lever by means of a rod extending substantially horizontally and parallel to the longitudinal centre plane of the vehicle, said double armed lever extending about parallel to the swivel arm and in horizontal direction, the other end of said double armed lever which is located farther away from the longitudinal centre plane being connected to the steering rod. In this way it can be achieved that the steering rod itself extends at a distance from the longitudinal centre plane of the vehicle, said distance being as large as possible. This means that said steering rod is extending itself close to the wheels so that the cranck levers can have relatively large dimensions and the forces exerted on the steering rod can be limited. The invention is further elucidated with reference to an embodiment shown in the drawing, in which: Fig. 1 schematically shows a top view of a tractor with semi-trailer, in a position which the parts are occupying while the vehicle is describing a curve; Fig. 2 schematically shows a bottom view of the semi-trailer with some swivel supported, steered wheels and the relating steering device; Fig. 3 shows a part of the device of Fig. 2 on an enlarged scale; and Fig. 4 shows the course of the guide path of the curve plate. In Fig. 1 the tractor 1 and the semi-trailer 2 coupled therewith describe a circular path around the centre 0. The semi-trailer 2 rests on the rearward part of the tractor 1 and is supported by this in such a way that it is pivotably around an axis via a king pin 8 standing perpendicular to the plane of the drawing. The semi-­ trailer 2 has three pairs of wheels 4, 5 and 6. In order to prevent that specific wheels might start to slide in respect of the ground when changing the direction of driving, the wheels 5 and 6 are steerable in such a way that when describing a curve the intersection of the imaginary extended wheel axles always coincides with the centre 0 of the circular movement. In Fig. 2, which is showing the semi-trailer 2 more in detail, the curve plate 7 is shown which simultaneously forms the coupling plate with which the semi-trailer 2 rests on the rearward part of the tractor 1. The curve plate 7 is pivotable around the king pin 8 and is coupled with the tractor 1 by means of a coupling wedge. The curve plate 7 is provided with the curve paths 10 and 11 in which the curve rollers 12 and 13 respectively are running. As appears in particular from Fig. 4 the curve paths 10 and 11 may merge into each other. The curve rollers 12 and 13 are connected to the arms 14 and 15 respectively, each being fixedly connected to the arms 16 and 17 respectively to form a cranck lever. The two cranck levers are pivotable around the axis 18 and 19 respectively extending parallel with the king pin 8. The free ends of the arms 16 and 17 are connected to steering rods 22 and 23 respectively by means of joints 20 and 21 respectively. By means of ball joints 24 and 25 the steering rods 22 and 23 respectively are connected with the double armed levers 26 and 27 respectively being pivotable around the fulcrums 28 and 29 respectively. The other ends of said levers 26 and 27 are connected to the rods 32 and 33 respectively by means of the joints 30 and 31 respectively, said rods being attached to the swivel arms 36 and 37 respectively by means of the joints 34 and 35 respectively, said swivel arms cooperating with the swivel bodies 38 and 39 respectively. So when the curve plate 7 rotates the swivel steering parts of the second pair of wheels 40, 41 are controlled. The swivel bodies 44 and 45 of the third pair of wheels 42 and 43 respectively are provided with the swivel arms 46 and 47 respectively. These swivel arms as such are hingedly connected to the rods 48 and 49 respectively, cooperating with levers 50 and 51 respectively which are hingedly supported in the points 52 and 53 respectively. By means of rods 54 and 55 the levers 50 and 51 respec­ tively are connected to the levers 26 and 27 respectively. As in particular appears from Fig. 1 the wheels 42 and 43 will have to be deflected further than the wheels 40 and 41 respectively so that the pivot points 52 and 53 respectively of the levers 50 and 51 respectively will have to be staggered in respect of the pivot points 28 and 29 respectively of the levers 26 and 27 respectively. Of course it is, however, also possible to obtain another deflection of the wheels 42 and 43 than of the wheels 40 and 41 respectively in another way. Furthermore the swivel bodies 44 and 45 of the wheels 42 and 43 respectively additionally are connected with coupling levers 56 and 57 respectively, which are connected to each other by means of the track rod 58. In this way a particular stable steering device is obtained in which each tolerance in the system can be avoided to a high degree so that shimmy of the wheels is opposed. Fig. 4 shows in more detail the course of the curve paths 10, 11 which is incorporated in the curve plate 7, the rollers 12 and 13 running through said curve path and being connected to the cranck levers 14, 16 and 15, 17 respectively. The curve plate 7 can rotate around the king pin 8 which is fixedly connected to the tractor 1. When the tractor 1 and the semi-trailer 2 are in line with each other, the rollers 12 and 13 will be at a distance a from the king pin 8 and will be symmetrically positioned in respect of the longitudinal centre plane V of the semi-­ trailer 2. In Fig. 4 a circle has been drawn in dashed lines with the kin pin 8 as centre and with the distance a as radius. If now the vehicle combination is going to describe a curve as is shown in Fig. 1, the curve plate 7 will rotate in the direction of the arrow P in respect of the semi-­ trailer 2. The curve roller 12 then will be moved outwardly and so being brought at a distance from the point 8 which is larger than the distance a , whereas the curve roller 13 will be brought to a position at a smaller distance from the point 8. As appears from Fig. 1, however, the angle of rotation of the outer wheel 40 of the pair of wheels 5 will have to be smaller than the angle of rotation of the wheel 41 of said pair of wheels, so that the distance a which the curve roller 12 is moving outwardly will have to be smaller than the distance b which the curve roller 13 is moving inwardly. After an angle of rotation β so the distance b will be smaller than the distance c. After an angle of rotation α, which will be 50° at the most, the distances b and c will not change any more so that those parts of the curve, located on both sides of the pane V, will have the shape of a part of a circle with a radius d and e respectively.

Claims: 1. A vehicle, such as a trailer or semi-trailer (2), suitable to be coupled with a tractor (1), said vehicle (2) having one or more supporting axles with at the ends of at least one axle swivel-supported, steered wheels (5,6,40,41,42,43), a rod system being provided controlling a steering arm (36,37,46,47), connected with a swivel body (38,39,44,45) for steering the relevant wheels (40,41,42,43), characterized in that a swivel arm (36,37,46,47) is controlled by a steering rod (22,23,54,55) via a lever transmission (26,27,32,33,48,49,50,51), said steering rod (22,23,54,55) extending substantially parallel with the longitudinal centre line of the vehicle (2) and being connected to the one arm (16,17) of a cranck lever (14,16; 15,17), the fulcrum (18,19) of said lever (14,16; 15,17) being pivotally supported by the vehicle (2), the other arm (14,15) of said lever (14,16; 15,17) carrying a follower (12,13) which is located in a guiding path (10,11) of a curve plate (7) being pivotally supported by the vehicle (2) and being secured against pivoting with respect to the tractor (1) on coupling of the vehicle (2) with the tractor (1). 2. A vehicle according to claim 1, characterized in that the swivel arms (36,37,46,47) of the wheels (40,41, 42,43) at both ends of an axle each are controlled by a steering rod (22,23,54,55) and a relating cranck lever (14,16; 15,17), the follower (12,13) of both cranck levers (14,16; 15,17) cooperating with one single guiding path (10,11) incorporated in the curve plate (7). 3. A vehicle according to claim 1 or 2, characterized in that each swivel arm (36,37,46,47) is directed substan­ tially towards the longitudinal centre plane (V) of the vehicle (2) and the end of said swivel arm (36,37, 46,47) is connected to one end of a double armed lever (26,27,50,51) by means of a rod (32,33,48,49) extending substantially horizontally and parallel to the longitu­ dinal centre plane (V) of the vehicle (2) said double armed lever (32,33,48,49) extending about parallel to the swivel arm (36,37,46,47) and in horizontal direction, the other end of said double armed lever (32,33,48,49) which is located farther away from the longitudinal centre plane (V) being connected to the steering rod (22,23,54,55).

Inventors: KENNIS, JACOBUS PETRUS NICO MARIA
Applicants: KENNIS' MACHINEFABRIEK B.V.
Application year: 1986
Main classification: B62D13
IPC codes: B62D13