In a fork-lift truck comprising a wheeled structure carrying a lifting arm with a first part articulated at its rear end to the structure and a second part projecting downwardly from the front end of the first part and carrying a forked loading platform, and a jack for raising and lowering the arm, the lifting arm is supported by the wheeled structure so as to be orientable about a substantially vertical axis and two adjacent caliper units located in a general V configuration are provided to move the forked platform linearly relative to the lifting arm. Each caliper unit includes two plates having one mutual hinged articulation end and opposite articulation ends respectively hinged to the second part of the lifting arm and to the forked platform, the hinged articulations of the caliper units having respective axes which diverge downwardly and are substantially perpendicular to each other. Actuators are interposed between the two plates of each caliper unit for opening and closing them simultaneously.

The inspection car is intended to inspect the lower side of the bridge construction of a high level road from above the high level road as well as from the ground and it comprises a swingable and extensible boom vertically swingably pivoted on a rotatable pedestal rotatably mounted on the chassis of the car about the vertical rotational axis of the pedestal, a reciprocal boom pivotally mounted on the tip of the swingable and extensible boom through a saddle, and an extensible inspection passageway pivotally connected to one end of the reciprocal boom, the passageway being swingable between a position parallel to the reciprocal boom and a position at right angle thereto while it is allowed to be rotated about the longitudinal axis of the reciprocal boom, a plurality of hydraulic cylinder means for the movement of the respective components listed above, and a control device for detecting the amount of movement of each component and controlling the movement thereof on the basis of the detected amount of movement of each component for the required operation of the inspection car. The control device has a function to judge the permission/inhibition of the movements of the respective components under predetermined conditions of the corelationship of the movements of the respective components.

Foldable link rod system to be placed on a travelling frame comprises pivotally suspended link rods (16, 18) for raising and lowering an operation platform (14). A rotating stool (20) constitutes the connection between two link rods (16 and 18) which are placed in continuation to each other. The one part of the rotating stool (20) is linked to the free end of the first link rod (16) which at its opposite end is pivotally linked to a swinging rod system (26, 28, 30, 32). The second link rod (18) is linked to the other part of the rotating stool and at its other end it is linked to the operation platform (14). The two link rods are pivotal by means of each of their swinging devices (54-70) which are supported on the travelling frame (10, 12) and the rotating stool (20), respectively. The swinging rod system (26, 28, 30, 32) is adapted to communicate a swinging movement to the first link rod (16), the free end of which follows or yet is close to a leadline intersecting this end in one of the end positions of the link rod. At the same time, the rotating stool (20) of the swinging rod system (26, 28, 30, 32) is kept in a mainly horizontal position.

An articulated boom and assembly comprising: (a) a lower boom arm; (b) an upper boom arm foldable over the lower boom arm and pivotal with respect to the lower boom arm; (c) hydraulic cylinders positioned between the boom arms and having piston rods extending therefrom, the hydraulic cylinders with the piston rods, pivotally secured at one end to each boom arm intermediate the boom arm's ends, one hydraulic cylinder being pivotally secured to the underside of the upper arm and the other cylinder pivotally secured to the upper side of the lower arm facing the upper side when the upper arm is folded over the lower arm; (d) a linkage for pivotally connecting the upper arm, lower arm and hydraulic cylinders, the linkage comprising three points of connection, the points when linearly connected forming a triangle with the points of connection forming the apexes of the triangle, with: (i) one apex of the triangle directed towards the hydraulic cylinders and piston rods between the upper and lower boom arms and the linkage being pivotally connected at this point of connection to the free ends of the cylinders or piston rods not connected to the arms; (ii) another apex of the triangle proximate the upper arm being secured to the end of the upper arm proximate this point of connection; and (iii) another apex of the triangle proximate the lower arm being pivotally secured to the end of the lower arm at this point of connection.

A fluid-powered rotatable work platform assembly for use with a vehicle such as a vehicle having an arm for positioning the assembly. The assembly includes a work platform or support configured to support a load, a body having a cavity extending along a longitudinal axis, and an output shaft rotatably disposed within the body generally coaxial with the longitudinal axis. A linear-to-rotary force transmitting member is positioned within the cavity of the body and engaged with the body and the output shaft to translate linear motion of the force transmitting member to rotational motion of one of the output shaft and the body relative to the other. The work platform is coupled to one of the body and the output shaft with at least one link and the arm of the vehicle is coupled to the other of the body and the output shaft so that when the output shaft and the body rotate relative to one another, the work platform rotates relative to the arm of the vehicle, while the pivoting link allows the work platform to move downward under the load. A sensor is operatively coupled to the work platform to sense the downward movement and/or an increasing load on the work platform.