LOAD CARRYING FLOOR

Abstract: A load carrying floor (1), more particularly of a load transporting vehicle, provided with a number of roller tracks (2) disposed parallel to one another, on which a load may be displaced across the floor (1) with low frictional resistance, displacement and holding means being provided, comprising at least one additional track of rollers, over which a friction belt (3) is trained, which is adapted to get into frictional contact with the lower side of a load and to be selectively driven in one direction or the other, so as to displace the load in one direc­ tion or the other and parallel to the roller tracks (2). The ends of the friction belt (3) are each fastened for winding or unwinding respectively on a drum (4) provided at the respective end of the floor (1).

Description: The invention relates to a load carrying floor, more particularly of a load transporting vehicle, provided with a number of roller tracks disposed parallel to one another, on which a load may be displaced across the floor with low frictional resistance, the rollers of said tracks being vertically adjustably mounted between an inactive position, in which they are fully retracted below the upper floor surface and an active position, in which they project within their upper portions just above the upper floor surface, displacement and holding means being provided, comprising at least one additional track of vertically adjustable rollers, over which a friction belt is trained, which is adapted to get into frictional contact with the lower side of a load and to be selectively driven in one direction or the other, so as to displace the load in one direction or the other and parallel to the roller tracks. A load carrying floor of this type is disclosed in EP-A-0002106 and is used e.g. in load carrying vehicles which are designed for transporting containers and/or pallets. The rollers of the relatively narrow roller tracks are mounted for free rotation and have their upper portions, in the active supporting position, projecting just above floor level. Depending of the (uniform) width of the pallets or containers the load carrying floor surface may consist of a plurality of juxtaposed sections which may each comprise e.g. two roller tracks to support the respective pallets or containers adjacent their longitudinal edges. Relatively slight horizontal forces are sufficient to displace even heavy loads across such a load carrying floor, provided with roller tracks. In certain situations, such as in case of a sloping load supporting floor, uncontrolled, danger involving displacements could even occur. For such situations the friction belt forms an effective displacement and holding means, causing each load displacement across the load supporting floor to take place in a controlled manner. In the well-known load carrying floor referred to hereinabove said friction belt is designed for a flat load carrying floor and is carried out as an endless belt. It requires special structural provisions and construction height to accomodate the returning of lower run of the belt(s) and the inherent belt-tensioning structure under the load carrying floor. The invention aims at providing a friction belt of the general type above referred to in a stepped load carrying floor, such as the floor of a goose neck trailer. In accordance with the invention this aim is achieved by the features of the characteristic clause of the attached main claim. A particular embodiment of the invention may be obtained when applying the invention in the specific stepped load carrying floor disclosed in Applicant's EP-A-0219151, which was published on the 22nd of April, 1987. Accordingly this particular embodiment is characterized by the additional features of claim 2. It is to be noted that e.g. EP-A-0081695 and GB-A-543.658 disclose a cargo carrying vehicle in which the load supporting floor of which is constituted by a belt supported on rollers and covering the entire width of the floor. The ends of the belt are fastened for winding and unwinding respectively on drums provided at both ends of the floor. In this case, due to the belt covering the entire floor surface, the belt is in permanent contact with the load; with such a construction it will not be possible e.g. to move the belt in the unloading direction without taking along any load which has been previously deposited in the cargo space of the vehicle. The invention will be hereinafter further described by way of example with reference to the drawing. Fig. 1 is a diagrammatic perspective view of a stepped floor of a cargo transporting vehicle of the goose neck type; Fig. 2 is a longitudinal cross-sectional view according to line II-II in fig. 1; Fig. 3 is a cross-sectional view through a friction belt and its base, in which the left half is shown in the inactive or recessed position and the right half is shown in the active or lifted position and Fig. 4 shows the hydraulic diagram of the drive of the friction belt. The load carrying floor 1 shown in fig. 1 is e.g. of the type described in EP-A-0219151, in which the intermediary section 1C may be elevated as a lifting platform, from the plane of the rear section 1A into the level of the front section 1B. In the example shown in the drawing the floor is provided with two roller tracks 2 extending along the entire floor length, on which the loads, e.g. containers or pallets, may be easily displaced. The use of such roller tracks in load supporting floors is known. The individual rollers are mostly mounted for free rotation about their transversally oriented axes. Often the rollers are supported in groups on hollow carriers inserted into the floor. These carriers may, by supplying a pressurized fluid into the hollow interior, be extended in vertical direction to elevate the rollers from an inactive position in which they are sunk into the floor, into an active supporting position, in which they are projecting with their upper portions just beyond the floor surface. Between the two rollers tracks 2 a friction belt 3 according to the present invention is provided with extends along the entire floor length. The free ends of this friction belt are each attached for winding or unwinding respectively to a drum 4 or 5 respectively provided at the front end or rear end respectively below the load supporting floor 1. The friction belt 3 is designed to get into frictional engagement with the lower side of a load placed onto the roller tracks so as to take said load along when driving the belt in the forward or rearward direction. The friction belt 3 is movably supported with low friction on a base 6 inserted in the proper floor. In the example shown in the drawing this base is formed by a roller track of the type which has been herein before described with reference to the two roller tracks 2 (vide fig. 3). In the floor 1 a longitudinally extending housing 15 is inserted, in which the rollers 2′ which are rotatably mounted in a frame 16, are supported with the intermediary of a carrier 17. The carrier is hollow and is formed of an elastic material, so that by supplying or discharging respectively of a pressurized fluid to (from) the hollow carrier interior an adjustment of the vertical position of the frame with rollers 16, 2′ between a lower and an upper relative position relative to the floor 1 may be effected. The upper position is shown in the right half of fig. 3. In this position the carrier 17 is inflated ― by supplying a suitable pressurized fluid, such as pressurized air ― to its maximum height which height is reached when the frame 16 has engaged a shoulder of the housing 5. The rollers 2′ project through corresponding openings in a cover plate 15a overlying the upper side of the housing 15; the frictionbelt 3 is thus elevated to a level above the floor surface. In the lower position, which is shown in the left half of fig. 3, the carrier 17 is in the deflated position, due to the fact that the hollow interior of the carrier is evacuated and consequently its volume has been reduced to substantially zero. In this lower position the rollers 2′ are positioned just below the cover plate 15a, while the friction belt is laying on the cover plate 15a in a position just under the level of the floor 1 and just free from engagement with the rollers 2′. Preverably the frame and the carrier are divided into independent longitudinal sections, as is known per se with roller tracks. These longitudinal sections may then be independently supplied by pressurized fluid, so that they may be independently adjusted in height, together with the section of the friction belt sections carried by them. At the front and rear end of the floor 1 the friction belt 3 leads via guiding rollers 7 and 8 to drums 5 and 4 (fig. 2). The shafts 4a and 5a of the drums 4 and 5 respectively are coupled to drive motors, which have not been shown in fig. 1 but have been represented in fig. 4 as hydromotors 18 and 19. In the transition zone between the floor sections 1B and 1C and also in that between the floor sections 1C and 1A the friction belt 3 is guided by three additional rollers 9, 10, 11 and 12, 13, 14 respectively. The axis of the roller 9 has a fixed position relative to the front floor section 1B, whereas the axes of the rollers 13 and 14 take a fixed position relative to the rear floor section 1A. The rollers 10, 11 and 12 are carried by the intermediary floor sections 1C and consequently follow the latter in its upward and downward movements relative to the two other, fixed floor sections. It will be understood that with such a guide roller system the total friction belt length between the drums 4 and 5 will not vary when the floor section 1C is moving up and down. In fig. 2 the full line portions 3′ indicate the situation, in which the free friction belt length required for fulfilling the transporting function is completely wound on the (rear) drum 4, while the front drum 5 is (practically) "empty". From this situation the process of loading can take place. For this purpose the friction belt 3 and the roller tracks 2 are put into the active transporting position by supplying pressurized fluid to the carrier (sections) 17. The friction belt will thus be pressed against the lower side of a load, e.g. a container, placed on the rear portion of the floor. Thereupon the control valve 20 (vide the diagram of fig. 4) is moved, e.g. with the intermediary of an electrical signal, from the neutral position shown in the drawing to the right (the loading position). This causes the pressure line P to be connected to hydromotor 19 so that the latter starts rotating in a direction corresponding to the winding direction I (Fig. 2) of drum 5, whereas hydromotor 18 is connected to return line T and as a consequence of this will be taken along against the winding direction II of drum 4. The counter pressure exerted by the motor 18 (which counter pressure may be adjustable, if desired) will keep the friction belt taut. As soon as a load or the complete load had reached its final destination on the floor, the roller tracks and the friction belt or sections of the same may lowered into their inactive positions to allow the load to get into frictional engagement with the proper floor. Upon completion of the loading process the major portion of the free frictional belt length will have been wound onto the front drum 5. From that position onwards the unloading may take place, for which purpose the roller tracks 2 and the friction belt 5 are moved into their active positions again, while the valve in fig. 4 has to be moved to the left (into the unloading position). During the loading as well as during the unloading procedure use may be made of the lift platform section 1C of the floor in a manner as disclosed in Applicant's EP-A-0219151. It will be understood, that the well-known height adjusting system for the roller tracks 2 and the friction belt 3 may be simply connected to the hydraulic drive system for the belt 3, such that the required safety is obtained. The invention is not limited to the example shown in the drawing. Within the scope of the invention alternative systems for the height-adjustment of the roller tracks 2 and/or the friction belt 3 may be used.

Claims: 1. A load carrying floor, more particularly of a load transporting vehicle, provided with a number of roller tracks (2) disposed parallel to one another, on which a load may be displaced across the floor (1) with low frictional resistance, the rollers of said tracks (2) being vertically adjustably mounted between an inactive position, in which they are fully retracted below the upper floor surface and an active position, in which they project within their upper portions just above the upper floor surface, displacement and holding means being provided, comprising at least one additional track of vertically adjustable rollers (6; 2′), over which a friction belt (3) is trained, which is adapted to get into frictional contact with the lower side of a load and to be selectively driven in one diection or the other, so as to displace the load in one direction or the other and parallel to the roller tracks (2; 6, 2′), characterized in that the belt (3) is covering both the higher level section (1B) and the lower level section (1C + 1A) of a stepped load carrying floor, the belt (3) having two ends which are each fastened for winding or unwinding respectively on a drum (4; 5) provided at the respective end of the floor and each being equiped with selectively operable drive means, an additional guide roller (11) being provided at the transition between the higher (1B) and lower floor sections (1C + 1A) which is located under said lower floor section (1C + 1A) so as to guide the belt coming from the respective end roller (10) of the lower floor section (1C + 1A) into a loop that directs the belt first downwardly and then upwardly along the (vertical) step towards the respective end roller (9) of said high level floor section (1B). 2. A load carrying floor according to claim 1, characterized in that the lower level floor section (1C + 1A) is divided into a stationary part (1A) and a movable part (1C), the latter part adjoining the higher level floor section (1B) and being adapted to move between the (low) level of the stationary floor part (1A) and the (high) level of the higher level floor section (1B), and further caracterized in that a second additional guide roller (14) is provided at the transition between the two parts (1A, 1C) of the lower level floor section (1C + 1A), said second additional guide roller (14) being located under said stationary (1A) in a fixed vertical position, whereas the first additional guide roller (11) is mounted for moving up and down with said movaable floor part 1C. 3. A load carrying floor, according to claims 1-2, characterized in that said drums (3, 4) are connected to hydraulic motors (18, 19), which are hydraulically connected such that they may be selectively driven in the winding direction of the respective drum.

Inventors: THUNNISSEN, KEES WIM
Applicants: TALSON TRANSPORT ENGINEERING B.V.
Application year: 1988
Main classification: B60P1
IPC codes: B60P1