Device for indicating the position of the platform in cranes with articulated booms, especially camera cranes

摘要

1,130,719. Camera supports; fluid-pressure servomotor systems. ROUMANIA STATE BOARD FOR CULTURE and ART. March 31, 1966 [April 1, 1965 (2)], No.14296/66. Headings G2J and G3P. A device for indicating the position of the platform in cranes, such as camera cranes, having a pair of articulated booms comprises a mechanical arrangement for resolving the movements of each boom into its vertical and horizontal components, and separately adding them. As shown a parallelogram linkage 1, 2, 3, Fig. 1 is so fixed to the upper boom that link 3 is parallel thereto and, through a slide mechanism, the indicator 5 moves a distance proportional to the vertical displacement of the upper boom. A shaft 6 fixed to the lower boom along its lower pivotal axis moves, through lever 7, pin 8 and groove 9, a cylinder 10, which is slidable on a shaft 11, so that by reading indicator 5 against a scale on cylinder 10 the full vertical displacement of the camera platform is indicated. Similarly horizontal movement of the upper boom is transmitted by the parallelogram linkage, hollow shaft 12, lever 23 and rod 14 to an indicator a and that of the lower boom through shaft 6 and lever 15 to a graduated rule 16 co-operating with indicator a. Rotation of the crane is measured by indicator 5 against the cylinder 10 which is rotated by key and slot connection b whenever shaft 11 is rotated through belt 18 and pulley 19 from the pulley 17 fixed to the crane. To enable the camera platform to move vertically without horizontal movement, a hydraulic valve (21), Fig. 3 (not shown), is connected to rod (14) and a piston (22) to rule (16) the arrangement being such that when the lower boom is moved by a hydraulic cylinder, if the platform moves horizontally there will be differential movement of piston (22) and valve (21) and this is used to control a hydraulic cylinder (20) connected between the two booms so as to eliminate such horizontal movement and thus restore the initial relationship between piston (22) and valve (21). Alternatively a similar arrangement may be associated with indicator 5 and cylinder 10 so that the camera platform is moved horizontally without veritcal movement.