Retractable suspended scaffolding on a self-propelled truck, particularly adapted for maintenance work on road-bridges and the like

Claim 1

A retractable suspended scaffolding, particularly adapted for maintenance work upon the bridge structures along roads, at points or areas to difficult access, characterized by the fact that it essentially consists of a working gangway capable of being arranged and kept suspended under the structure of a bridge, a viaduct or the like, by means of a set of mechanisms operated by oleodynamically controlled jacks, hydraulic motors and manually controlled reduction units; that such mechanisms with their controlling means are mounted on a self-propelled flat-bed truck capable of automatically keeping a path parallel to the shoulder of the road, and that the mechanisms themselves comprise substantially, in the order, an articulated parallelogram which is integral with the plane (11) of the truck (1), operable through an oleodynamically controlled jack (13) and comprised of two pairs of arms, or cranks (7,8), kinematically associated to a stiff connection and support member (12) acting as a connecting rod; a center plate (16) driven by a motor reduction unit (19), integral with said connecting member (12) of the parallelogram and capable of supporting assuring its rotation on the vertical plane, a hollow support (17) within which an arm (18) that is square-shaped in cross-section is slidable, guided through said support (17) by means of cheeks with sliding shoes lined with an antifriction material, said arm (18) being provided with a plurality of connection elements, ears (29), longitudinally distributed at predetermined intervals along one of its faces and with a plurality of pairs of holes (62) longitudinally distributed at predetermined intervals along the opposing faces which are adjacent to the first-named face; a pair of center plates (20) arranged at the two ends of the hollow support (17) and of which one at least is integral with a gear wheel (21) coupled with a driving pinion (22), adapted to assure inside the support itself the rotation of the slidable arm (18) together with its guiding cheeks; a hydraulic jack (24) situated parallel to the hollow support (17) and supported by means of brackets (25) which are integral with the gear wheel (21), the rod (26) of the jack (24) acting downwardly along a vertical path, causing the running along the external corresponding face of the slidable arm (18) of a shoe (27) connected to said rod (26) by means of an extractable pin (28); a telescopic extension (31) of the slidable arm (18) having in the lower portion a header (33) coupled by means of a pin (38) to a bracket-shaped support (35) capable of effecting a rotation, in the vertical plane, of 90° at least with respect to said header (33) provided for supporting two reticular telescopic members (36,37) which substantially constitute the working gangway; manually controlled reduction units (51,52) connected to steel rope and transmission systems for sliding of the reticular telescopic elements (36,37) and their forward and backward displacement; a pair of rectilinear parallel guides (46) arranged along the face of the slidable arm (18) which is opposed to that which is provided with clamping or connecting ears (29), within said guides (46) sliding shoes (47) of an elevator service basket (48) controlled by a hydraulic windlass (49); stabilizing supplemental wheels (53) applied in correspondence of the right wheel of each axle of the truck (1); a motor reduction unit (60) applied to the twin wheel of the rear fixed axle of the truck (1), this reduction unit (60) being controllable by means of push-button panels both from the ground level and from the gangway.