Improvements in apparatus for measuring the work done by impact members

516,534. Testing physical qualities of materials. SOC. ANON DES HAUTS-FOURNEAUX DE LA CHIERS. June 23, 1938, No. 18699. Convention date, Feb. 18. [Class 106 (ii)] ] Relates to impact means for determining the resistance to fracture of a test piece, and consists in mounting the inertia member for movement along a guide rod to which it is locked at the end of its movement by a number of pawls which can be released to enable the inertia member to resume its normal position relatively to the impact member by means of turning a ring to disengage the pawls against the action of resilient means. A head 1 preferably of duralumin locks the apparatus on the tup and then acts as an impact member. A guide rod 2 fixed to the head is surrounded by a spring 3 attached at one end 4 to the head and at the other to weight 5. When the head is arrested by the impact device 11, the weight extends the spring the pawls 6 slipping over helical threads 8 on the rod 2 and holding the weight in the position reached. By unscrewing the ring 10 the rubber ring 7 is compressed and the pawls retracted to release the weight 5. The travel of the weight is read on the scale 9. The member 11 is of horse-shoe shape and supported by a steel column (not shown) extending down to the anvil block. The head 1 and rod 2 fit into brackets 12, 13 carried by the tup which brackets pass freely between the arms of the horse-shoe, the head not passing through and being arrested by the member 11. A locking device to prevent rebound of the head comprises bolts 14 actuated by springs 15 associated with double - acting levers 16 having fingers 17. Normally the levers 16 are horizontal and project into the gap of the horse-shoe while the head 1 in its fall engages them to release the bolts 14. The rod 2 at the bottom is secured by a bush 19 over which is looped a copper wire tightened by a screw tightener 20. When impact occurs the mechanical fuse formed by the wire breaks. Specifications 476,842 and 513,319 are referred to.