Technikatörténeti szemle 11. (1979)

TANULMÁNYOK - Petik Ferenc: The development of material testing machines

A change which has been effective up to our days was the invention of the pendulum type dynamometer. At the 1878 World Exhibition in Paris, two firms (Michele of Paris and Carrington from London) presented simultaneously the pendulum dynamometer suitable to follow forces arising in the specimen continouously [16]. The inventors, as well as Schopper after 1890, had employed the pendulum on Smaller, hand-operated machines (Fig. 14). Already in 1879, however, the Pohlmeyer tensile testing machine for 50 tons load, with hydraulic drive was ready, on which loads reduced by several levers were measured by the pendulum device.

Several factories tried to employ spring type dynamometers, but various problems had arisen on account of not sufficient stability of available spring materials. In Hungary a horizontal cloth tester with spring dynamometer, developed by Prof. S. Rejtő of the Polytechnical University was widely used (Fig. 15). The main advantage of the spring dynamometer is that it can follow strains of the specimen practically without inertia. To ensure the linear characteristics of the biscuit shaped springs on Rejtő’s machine, however, coupled with not sufficient material stability were difficult problems. Therefore the

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13. Dynamometer system with jockey-weight