GB762090A - Improvements in or relating to mechanical loading apparatus employing grab forks - Google Patents

Abstract

762,090. Grabbing machines. BONNEL, H. A. May 19, 1953 [May 19, 1952; March 3, 1953], No. 14070/53. Classes 78 (3) and 78 (4). A grab fork which can be locked open or closed is mounted at the end of a luffing and slewing jib 1, Fig. 1. As illustrated the jib 1 is luffed by a double-acting hydraulic ram and is carried by a column 2 which slews on the chassis 4 of a semi-trailer. The grab comprises tines 8 carried by frames 7 pivoted to a rod 6 sliding in a tube 5 to which the frames 7 are connected by chains 9. When the grab, in its open condition, is pressed down upon the material a flat portion 15, Fig. 3, of the rod 6 rises in the tube 5 until a flange 10 abuts the tube; during this motion a roller 16 carried by the member 15 pushes aside a sector 13 pivoted to the tube 5 and extending through a slot in its wall. A spring 17 subsequently returns the sector 13, locking the roller 16 in its upper position so that when the jib 1 is raised the grab fork closes on its load. To release the load a cable secured to a lever 18 carried by the sector 13 is pulled to cause the sector to release the roller 16. A further roller such as 16 may be provided for locking the grab fork in a partially closed condition. In an alternative construction of grab each set of tines is pivoted at one end of a transverse head at the lower end of the column 6 and the chains 9 are replaced by arms on the jaws connected by links to the tube 5 so that the grab fork is opened and closed by movement of the member 15. The jib may be luffed by a cable (Fig. 2, not shown), wound on a drum carried by the mast and secured at its ends to points on the jib spaced on opposite sides of the luffing pivot.