Technikatörténeti szemle 11. (1979)
TANULMÁNYOK - Petik Ferenc: The development of material testing machines
weight pieces applied at the end of angle lever e with a transmission ratio of 1 : 500. When the specimen was strained, to restore horizontal position of the lever, piston c and sledge d fixed to it were displaced by oil pressure. Accordingly tests were performed also on this machine at constant loads. The specimen was able to carry the load corresponding to the applied weight or not. For checking transmission ratio of the loading lever, the separately applicable balance f with a transmission ratio of 1 : 10 was used. Accuracy of force measurement satisfied the +1 p. c. requirement specified in our days. The machine was suited for testing complete bridge elements, the space for tensile tests being 9,5 m long. On the extensometer 0,1 mm was readable, 0,01 mm comfortably estimated. For handling the machine two persons were required. One of them applied weight pieces and actuated the pump, the other was the actual material tester. Later, one of design aims was to realize one- man handling. Other tensile testers known from the middle of the last century were also balance-like designs, as e. g. the tensile tester and the first fatigue testers of Wohler [13]. Material testing laboratories starting their operation at the middle of the 19th century needed a greater number of testing machines. Accordingly small series production was organized in factories specialized for this branch. Several well-known firms of our days had been already working about a hundred years ago (thus e. g. MAN Mohr-Federhaff, Schopper in Germany, Amsler in Switzerland, Riehle and Olsen in the USA). From this time on, a steadily growing selection of machines could be ordered from catalogues or on the basis of reference lists. Development of design in the second half of the 19th century Load generating mechanism were working on a mechanical or hydraulic principle. Looking backwards today, one does not presume that power source was a problem at that time. Individual electrical drive for each machine, what is obvious today, did not appear before the turn of century. Until that time large capacity material testing ,machines were driven by a power shafting and driving belt, if manual actuating was not sufficient any more (Fig. 12). Dis225 11. The scheme of Werder’s machine
