Patent GB-804442-A (GB)
Title: Improvements relating to portable structural units, particularly bridge units
IPC: E01D15/127
Filed: 1955-11-07
Abstract: 804,442. Portable bridges, warehouses or garages. SMITH, C. A. V. Oct. 31, 1956 [Nov. 7, 1955], No. 31787/55. Class 20(1) A portable bridge or other structural unit such as a floor, wall, roof or a car park comprises a narrow central structure of longitudinal &c. girders 1, Fig. 4, to which side wings are folded on vertical pivots and openable out to provide the full width of the bridge. The wings comprise a structure covered by a sheet of material or of multiple sheets which slide under each other or roll up automatically. The central structure has pivoting-down ground castors 6 so that the bridge can be towed into position. When the wings are opened out, telescopic legs 12 thereon are forced down on the ground to take the whole weight and free the castors 6 from ground contact. To expand the structure from the closed position Fig. 2 to open position Fig. 3 a motor driven rotor 13 pulls the attached connecting rods 14 to extend links 15 which push slides 16 towards the respective ends of the structure. Links 18 then push outwards the folding girders 3 at both ends and sides about their vertical pivots, the girders carrying with them the superposed longitudinals 25 of the bridge which run on longitudinal rollers 28 and have transverse top rollers 33, Fig. 5, on which rest the metal decking 24. The telescopic legs 12 are also moved out Fig. 5 by the pivoting out of the girders 3 which are attached to carriage 7 carrying top and bottom rollers 8 running in channels 9 attached to the longitudinal joist 11 from which the legs 12 depend. The legs 12 are then telescopically extended down to bear on the ground and raise the castors 6. The castors 6 are then pivoted up under the bridge by jacks 5a of the type used for aircraft undercarriages. The top surface of the bridge comprises flexible sheets 19 of roller shutter type i.e. of rigid parallel laths secured to a fabric or like flexible backing which unrolls from rollers 20, Fig. 5, as the sides of the structure are expanded out. The flexible sheets 19 are supported on transverse stringers 24, Fig. 5, supported on the rollers 33 of longitudinal ribs 25 themselves supported on the pivoting out girders 3 by rollers 29, Fig. 7, running in a channel 31 the roller assembly pivoting on a vertical axis as outward or inward folding proceeds when the ribs 25 are spaced out or in with the rest of the side wings. The stringers 24, Fig. 2, are arranged in chains of six with pin and slot connection between them so that each chain can either be in close echelon as in Fig. 2 or expanded as in Fig. 4, The outermost stringers 24 are attached to the joists 11 to move out with them, and have a downward curve 24a to lead the flexible sheet 19 smoothly over them. The flexible sheet 19 is automatically rolled up on its roller 20 when the side wings are folded in, by means of a pin 39 on the folding-in girder 3 sliding along a coarser peripheral groove 39 in a roller 36, the end gear wheel 38 of which rotates a gear 37 to rotate the rolling up roller 20. Narrower ramps are provided at each end of the opened out bridge. The ramp may be carried on top of the folded bridge during transport on the castors 6. In another form the central structure 41, 42, Fig. 9, towed on wheels 56, 58 has fluid pressure and suction operated telescopic tube beams 44 which extend sideways taking with them the overlapping deck plates 49. At least one staircase is provided leading from the ground to the decking or the roof of a building. Flower boxes or small showcases may replace the side rails. In Fig. 13 (not shown) the structure is self propelled the ground wheels being driven e.g. by I.C. engines and swivellable for steering. To increase the width the side wings may have hinged flaps. Specification 779,361 is referred to.