GB926254A - Air glided load support - Google Patents

Abstract

926,254. Weighing-apparatus. DOUGLAS AIRCRAFT CO. Inc. Sept. 6, 1961 [Sept. 6, 1960], No. 31988/61. Class 143. [Also in Group XXX] The ground-engaging member of a load supporting device has a yieldable cushionattached to its lower face and a passage through which air is supplied to provide a film of air thereunder to serve as an aerostatic support and a frictionless bearing for the device. The device has particular application to the weighing of aircraft whereby shifts in the attitude of the aircraft and irregularities in the ground surface are accommodated to maintain the support vertical and obviate side loads. Each weighing pad 70 on the vehicle (in the case of an aircraft there may be three weighing pads) rests on a load cell 74 which is supported on the upper end of the piston 58 of an hydraulic jack 20, during the weighing operation, and the hydraulic jack is supported by the legs 12, 14, 16 of the derrick through a spider 18. The supporting bearing 30 of each leg of the derrick comprises a backing plate 48 with a central aperture closed by a plate 60 which is in turn apertured for the passage of a shaft 38. A disc 50 of elastomeric material is bonded to the underside of the plate 48 at 52 and its outer, bottom surface is covered with a tough skin 80. The material of the disc 50 may be multi-cellular, natural or synthetic rubber, or foamed polyurethane, and the material of the skin 80 may also be rubber or plastic and may be reinforced with a nylon textile fabric. The shaft 38 is hollow and is screw-threaded to screw in and out of a boss 36 which is welded to a plate 34 which is in turn welded to the foot of the leg, e.g. 14, of the derrick. The disc 50 is recessed to provide a space 37 and the bore 46 of the shaft 38 is in communication with this space through members 44, 54, which are secured by studs 64, the upper part of the member 44 having a spherical seating. The lower end of the shaft 38 is shaped to engage this seating and form a ball-and-socket combination. The vehicle to be weighed is levelled, and the supporting struts brought to the vertical, by operation of the hydraulic jack 20 of each derrick and by adjustment of the feet 30 by screwing each individual shaft 38 up or down by a handcrank 32. The principal levelling agent for the weighing operation is compressed air interposed as a layer between the bottom of the disc 50 and the floor, the air being introduced to the space 37 through the bore 46. This, combined with the resilience of the disc 50 and the ball-and-socket combination, obviates the effect of irregularities in the surface of the floor.