GB594643A - Portable folding scaffold - Google Patents

Abstract

594,643. Ladder - scaffolding. SWAISGOOD, R. H. May 24, 1944, No. 10006. [Class 20(ii)] [Also in Group XXX] A stand, for use in servicing aeroplanes, has a platform 12, Fig. 1, adapted to be lowered and raised relative to a rectangular base frame 10 by means of two pairs of members 26, 26a, each member having one end pivotally connected to the platform and the other end pivoted to the base, and a hydraulic piston and cylinder assembly 44a, 40 pivoted, at one end, to a cross member 36 on the base and, at the other end, to a cross member 32, the point of attachment of the assembly to the base and of the members 26, 26a to the base being adjacent each other, whereby the distance through which the platform is moved is greater than the corresponding relative displacement between the piston and the cylinder. Steps are provided by U-shaped bars 33 pivoted to the members 26, 26a and treads 35 welded to the bars 33. The steps remain horizontal in any position of the platform owing to the pivotal connections. Guard rails 65 are pivoted to supports 69. The base is mounted on wheels 15, 18 and is provided with a telescopic tow bar 16. To enable the stand to be made rigid when in use, jacks J are provided to raise the wheels 15 from the ground. Each jack comprises a strut 20, Fig. 3, having a non-circular collar 21 and a plate 24 connected by a ball and socket joint to a screw member 25. A corresponding non - circular part 22 is formed on the base frame. When the part 21 engages over the part 22, and is also held against axial movement by a pin 23, the jack is rigidly fixed. To move the jack to the inoperative position (shown dotted) the pin is removed, the part 21 moved off the part 22, turned, and then moved onto the part 22. In a modification (Figs. 6, 7, and 8 not shown), a U-shaped clip is provided, in place of the pin, to prevent axial movement of the two non-circular parts. The hydraulic system comprises the member 36, serving as a reservoir, a force pump 50, Fig. 4, actuated by a lever 51, a one-way valve 56 and a hand-operated valve 58. In operation, to raise the platform, the valve 58 is closed and the pump operated, this draws fluid from the reservoir 36 through the tubes 54, 55 and forces it through the valve 56 to the cylinder 40. To lower the platform the valve 58 is opened and the fluid is expelled from the cylinder by the weight of the apparatus acting on the piston 44a. To prevent accidental lowering of the platform a pin is passed through one of several openings 61, Fig. 1, in the piston. The platform is protected by guards 70, removably secured in sockets 71. These guards may be used to extend the platform by inserting them in horizontal sockets secured to the undersides of the platform. Parts of the platform adjacent its edges are cut away to allow additional platforms to be hooked onto the tubular edges of the main platform.