TOWING VEHICLE

Abstract: Towing vehicle with a front axle carrying at least one wheel, and a rear axle, the wheels (10) of which are steerable and drivably connected to the driving means (6) of the vehicle, a coupling means (12) carried by the vehicle frame (2) and implemented to give substantially rigid interconnection of the vehicle frame (2) and an object (14) which is to be towed, and lifting means (54; 78; 86) adapted to allow lifting the front wheels (8) from the substructure (50) when the coupling means (12) is in engagement with said object (14). The lifting means acts between at least a part (2; 74; 82) of the vehicle frame and the front wheels (8).

Description: Towing vehicle. The present invention relates to a towing vehicle with a front axle carrying at least one wheel and a rear axle, the wheels of which are steerable and driveably connected to the vehicle driving means, a coupling means carried by the vehicle frame and implemented to provide substantially rigid interconnection of the vehicle frame and an object to be towed, and a lifting means adapted to allow lifting the front wheels from the substructure when the coupling means is in engagement with said object. Towing vehicles of this kind are intended inter alia for moving containers, or trailers etc. in terminus areas. The principles for the type of container handling intended here are well known and appear from the Swedish patent 7808448-0, for example. The occurrence of ramps having different slopes and configurations causes special problems in this container handling. One of these problems is the risk that the towing vehicle, when transportingg an empty and therefore comparatively light container down a ramp, will tip forwards so that the front wheels impact against the substructure during emergency braking. Should this happen, there " also occurs a heavy and uncontrollable vertical jerk of the empty container, until the forward edge reaches the ground, which can result in personal injury and material damage. A problem of the same character also occurs in emergency braking, if the respective driving wheels brake on substructure with different coefficients of friction, or if braking occurs during a turn. One of the wheels may just be passing through an oil slick, for example. The result here will also be a heavy and uncontrollable jerk by the empty container, this time laterally. The object of the present invention is to provide a solution to the above-mentioned and similar problems. The invention is based on the knowledge that the front wheels should be able to be brought very quickly into contact with the substructure when emergency situations of the kind mentioned above occur. In accordance with the invention, a towing vehicle of the kind defined in the introduction has been given the characterizing features disclosed in claim 1. The invention results in that the constructional implementation of the lifting means will be simple, since in principle it shall only function for lifting the lightly loaded front wheels relative the vehicle frame. At the same time, the lifting means may also be made easily operated and its function easily controllable, such that in accordance with a preferred embodiment of the invention, apparent from " the subclaims, the front wheels can always be kept at a predetermined distance from the substructure and rapidly brought into contact therewith in an emergency situation. By the front wheels being brought into contact with the substructure, the effects of the emergency situations discussed in the introduction are eliminated or mitigated. In the first case, the tipping case, there is hardly time for the 'jerk of the empty container to occur. In the second case, the friction of the front wheels against the substructure prevents slewing of the towing vehicle and thereby a transverse jerk of the load. The invention will now be described in detail with reference to the appended drawings, whereon figures 1 and 2 in plan view and side view, respectively, schematically illustrate a towing vehicle in accordance with the Invention, figures 3-5 in partial side views illustrate modifications of the front portion of the vehicle according to figures 1 and 2. Figure 6 Is a principle block diagram of a control arrangement for controlling raising and lowering of the front OMPI wheels of the vehicle according to figures 1-5, and figure 7 schematically illustrates in a view in the direction of arrows VII-VII in figure 1, a means for enabling taking up mutual torque stresses vertically between the vehicle and container. The vehicle in figures 1 and 2 has a rigid frame 2 carrying a driver's cabin 4 and a driving engine unit 6. The vehicle has front wheels 8 and rear wheels 10. In a manner known per se, but not illustrated, the rear wheels 10 are steerable and drivably connected to the unit 6. A lifting means acts between the front wheels 8 and the frame 2 such as to allow adjustment in height of the front wheels relative the frame, as will be described in detail below. To the rear, the vehicle carries a coupling means in the form of a rectangular frame 12 with coupling members for a container, trailer etc. 14, which is to be moved with the aid of the vehicle and which is carried by wheels at .its end not visible in figure 1. More specifically, the coupling members may be adapted for attaching the frame 12 to the corner fittings of the container etc. in a conventional manner. The frame 12 is carried by two U-sectioned brackets 18 which in turn, between their legs, are pivotably carried at 20 by each a side beam 22. At their forward ends the side beams 22 are pivotably mounted at 24 in mountings 26 carried by the vehicle frame 2. The brackets 18 are joined together by a cross beam 28 and the side beams 22 by a cross beam 30. Between pivot attachments 32, located low in brackets 34 connected to the frame 2, and pivot attachments at the cross beam 30, two hydraulic lifting cylinders 36 act. By means of the lifting cylinders 36 the side beams 22 can be lifted from a position essentially on level with the frame 2 to the position shown in figure 1 by rotational movement around the pivots 24. Two hydraulic rams 42 act between lower pivot attachments 38 in the frame 2 and pivot attachments 40 carried by the cross beam 28. More specifically, the brackets 18 and QMPI thereby the frame 12 can be caused to assume different angular positions relative the side beams 22 by means of the hydraulic cylinders 42. The described arrangement with the members 22, 42, 18 and 36 is preferably implemented and arranged such that there is also space for a fifth wheel on the frame and for coupling a semi-trailer when said members are not in use. For coupling the described towing vehicle to a container etc. resting on the substructure 50 the following measures are taken-- The towing vehicle is backed towards the end wall of the container 14 with the brackets 18 and frame 12 in the position Illustrated by dashed lines in figure 1. Coupling the frame 12 to the container 14 may be performed conventionally. Thereafter, the forward end of the container etc. 14 is lifted up by operating the hydraulic cylinders 36 and 42, the container 14 Is thus now carried at Its forward end by the frame and at its rear end by said wheels. The front wheels 8 are subsequently lif ed with the aid of said lifting means such that they go clear from the substructure 50. The towing vehicle can now be used for transporting the container 14, the rear wheels 10 serving as driving and steering wheels. By lifting the load in the described manner by means of the coupling means 12, 18 proper, there are avoided the problems connected with lifting a very heavy load a comparatively large distance by raising the vehicle frame relative its rear axle. In order to facilitate said adjustment in height of the front wheels 8, they have a smaller diameter than the rear wheels, and the front axle is carried by a toggle joint leg 52 and a hydraulic cylinder 54. By means of the latter the adjustment in height of the front wheels relative the frame may be carried through. In the vicinity of the front wheels, the frame carries sensing means for the clearance of the frame relative the substructure 50, in the form of at least one vertically movable slave wheel 56, adapted for running in continuous contact with the substructure. The wheel 56 is easily movable about a vertical joint and otherwise implemented such that the steering function of the back wheels 10 is not affected. The position of the wheel 56 in relation to the frame 2 is sensed with the aid of an inductive or capacitive transducer, not shown, of a type wellknown per see, which is mounted on the leg of the wheel 56 close to the frame. The transducer is represented by a block 58 in the block diagram of figure 6. The transducer is connected to a signal circuit 60, the output signal of which controls a valve system 62 for the adjusting movement of the hydraulic cylinder 54 such -that the wheel 8 always assumes a given height relative the wheel 56, i.e. a given distance in relation to the substructure 50. As an alternative to a slave wheel ' 56, some ' forffl. of impulse generator may be used, e.g. one for ultrasonic impulses. This has been indicated with dashed lines at 64 in figure 1. The reflected ultrasonic impulses are used conventionally to sense the distance to the substructure 50. The vehicle also includes an emergency brake, on the ■ drawings only illustrated in the form of a block 66 in figure 6, and, associated therewith, an emergency means 68. The emergency means 68 consists of an electrical circuit, adapted for being controlled by a signal obtained on the application of the emergency brake, and thereby actuating the circuit 60 and valve system 62 so that the front wheels 8 are brought rapidly into contact with the substructure 50. The function of the signal generator 60 of keeping the wheels 8 at a given distance from the substructure is thus inhibited in emergency situations. In practice, the distance between the wheels 8 and the substructure 50 is preferably selected as small as possible to allow rapid placing of the wheels against the substructure when necessary. The frame 12 and bracket 18 are attached to each other while permitting a mutual rotational movement in the plane of the frame 12. This mutual rotational movement is counteracted by four damping cylinders 70. This arrangement permits mutual relative rotation in the case of large loads, when the wheel pair of the vehicle is vertically rotated in relation to the rear wheels of the container. Alternatively, said rotational movement can be taken up between the vehicle frame and the rear axle. In figures 3 - 5 some alternative lifting means are Illustrated for positioning the front wheels relative the frame. In figure 3, the front wheels have greater diameter than those of the vehicle i figure 1, the toggle joint 52 and cylinder 54 being, however, at least partially accommodated in the vehicle frame, so that the wheel 8 in its retracted position may also be similarly accommodated in the frame. In figure 4 the frame is divided into a forward part 72 carrying the cabin and the front wheels 8 fixedly mounted, and a rear part 74 carrying the remaining mechanisms of the towing vehicle as illustrated in figure 1. The parts 72 and 74 are movably connected to each other in the vertical direction via guide means 76. At 78 power means are indicated in the form of a cylinder for vertical displacement of the frame part 72 in the guide arrangement 76. In figure 5 an arrangement is schematically illustrated, where the frame Is similarly divided into a part 80 carrying the cabin and front wheels 8 fixedly mounted and a main frame 82 carrying the remaining mechanisms of the towing vehicle. The two frame parts 80 and 82 are pivotably connected to each other at 84 about a horizontal transverse axle. Power means, Indicated in the form of a cylinder 86, act between the forward frame part 80 and a fixed part of the rear frame part 82, said part being schematically indicated at 88. "BU RE Solutions for lifting the wheels other than those described above are also conceivable. As an example may be mentioned retraction in the manner used for aircraft. The front wheels of the vehicle described above and illustrated on the drawings are as mentioned always kept sufficiently free from the substructure 50 to allow the steering and driving functions of the rear wheels 10. This means that if the vehicle and the container are to travel up a ramp after having travelled on a substantially horizontal substructure, the front wheels, as controlled by the described sensing and control means 58-64, may need to be raised still more so that they will be clear of the ramp from the beginning. By the vertical mobility of the front wheels and with the aid of the hydraulic cylinders 36 and 42, a far- reaching adaption to different slopes and configurations of ramps can be attained without the risk of the goods container 14 or the front wheels 8 being brought into contact with any part of the ramp. For example, if the vehicle and the container are to pass a hump on a ramp it may be necessary, for avoiding contact between the container and the hump, to raise the front end of the container primarily with the aid of the cylinders 36, with simultaneous adjustment by means of the cylinders 42 and the spacing of the front wheels with respect to the substructure. If the vehicle is to be moved without load, i.e. with the front wheels on the substructure, the sensing function for the front wheels is preferably disconnected. It will be noted that the described arrangements for positioning the front wheels also at least partially solves the problems discussed in the introduction, in conjunction with emergency braking with an empty container on a downwardly sloping ramp and/or emergency braking where the friction at the rear wheels is different for each wheel. The invention does not, of course, exclude the possibility of using a single front wheel.

Claims: Claims . 1. Towing vehicle with a front axle carrying a -least one wheel, and a rear axle, the wheels (10) of which are steerable, and drivably connected to the driving means (6) of the vehicle, a coupling means (12) carried by the vehicle frame (2) and implemented to provide a substantially rigid interconnection of the vehicle frame (2) and an object (14) to be towed, and lifting means (54;78;86) adapted to allow lifting of the front wheels (8) from the substructure (50) - when the coupling means (12) Is in engagement with said object (14), characterized in that the lifting means act between at least a part (2;74;82) of the vehicle frame and the front wheels (8). 2. Vehicle as claimmd in claim 1, characterized in that the front wheels (8) are retractably attached to the vehicle frame (2) and in that the lifting means (54) comprises a lifting cylinder arrangement between the front axle and the frame. 3. Vehicle as claimed in claim 2, characterized in that the frame contains recesses for the lifting means and, as the case may be, the front wheels. 4. Vehicle as claimed In claim 2 or 3, characterized in that the front wheels (8) have a less diameter than the back wheels (10). 5. Vehicle as claimed in claim 1, characterized in that a forward frame part (72;80) carrying the front wheels (8) is raisably connected to the rest (74;82) of the frame. 6. Vehicle as claimed in claim 5, characterized in that the forward frame part (80) is upwardly pivotably connected to the rest (82) of the frame. 7. Vehicle as claimed in claim 5, characterized in that the forward frame part (72) and the rest of the frame (74) are connected via vertical guide means (76), which are associated with power means (78) for vertical movement of the forward frame part. 8. Vehicle as claimmd in any of the preceding claims, characterized by sensing means (56;64) arranged at the front wheels (8) for sensing the clearance of the frame relative the substructure, the lifting means (54;78;86) being adapted to be controlled in response to this sensing, so that the distance of the front wheels from the substructure is kept substantially constant. 9. Vehicle as claimed in claim 8, characterized in that said sensing means include at least one vertically movable slave wheel (56) running in continuous contact with the substructure, but is Implemented such that the steering function of the rear wheels is not affected, a control circuit (60) including a transducer for the vertical position of the slave wheel, and signal generating means controlled by said transducer for generating control signals to an actuating means (62) for the lifting device. . ... 10. Vehicle as claimed in claim 8, characterized in that said sensing means includes a pulse generator (64), e.g. for ultrasonic pulses, arranged for sensing said clearance with the aid of reflected pulses, a signal circuit connected to the pulse generator being adapted for generating control signals to an actuating means for the lifting device. 11. Vehicle as claimed in any of the preceding claims, characterized by an emergency means (68) controlled by an emergency brake (66) of the vehicle, said emergency means being adapted for causing the lifting means (54) rapidly to bring the front wheels into contact with the substructure (50) at the occurrence of emergency braking. 12. Vehicle as claimed in claim 11 and claims 8, 9 or 10, characterized by means for inhibiting the function of said sensing means in case of emergency braking. OMPI 13. Vehicle as claimed in any of the preceding claims, characterized in that the coupling means (12,18) includes a flexible attachment means (70) allowing, in case of great loads, relative rotation between vehicle and towed object about an axis substantially parallel to the longitudinal direction of the vehicle. 14. Vehicle as claimed in any of the preceding claims, characterized in that the coupling means (12,18) is supported raisable and lowerable relative the vehicle frame (2). ' BU OM

Inventors: FROEROTH AOKE, FROEROTH, AOKE
Applicants: SVENSKA UTVECKLINGS AB, SVENSKA UTVECKLINGSAKTIEBOLAGET
Application year: 1983
Main classification: B65G7
IPC codes: B60P1, B60T7, B62D9, B62D49, B62D53, B62D61