Testing Machines
The great variety of testing-machines now in the market are an evidence of their growing importance. Wide-awake foundry-men everywhere realize the necessity for strict inspection of all the pig iron the purchase in order that their castings may be made to meet every requirement at the least possible cost. By means of the simplest of these machines, a sample of pig iron can be tested and its quality determined with approximate nearness in an incredibly short space of time, so that purchases need not be made blindfold as has been too frequently the case in the past. A more elaborate system of tests may be obtained by the use of Keep's test, which reveals every phase of a true test with the nicest accuracy: gradual load, impact, fluidity, tendency to curve, shrinkage, and deflection are at once determined by this machine in a manner truly astonishing. The Waterloo Transverse-testing Machine is arranged with the weighing-beam and system of multiplying levers, all tested and regulated in accord with the United States standard of weights at Washington, D.C., and delicately adjusted to weight the strain exerted on the specimen. The power exerting the strain on test-piece is produced by a worm and gear. The best of materials are used, and the workmanship is first-class in every particular.
The specimen in process of testing has one end resting upon an A-shaped piece of metal, the other end being suspended from the lower lever of the machine. The strain upon the test-piece is produced by turning a wheel below in front of the frame, which causes the stirrup, which is located at the centre point of specimen, to bear down upon the same, and the strain thus produced is transmitted to the weighing-beam through the intermediate lever. The weighing-beam is kept in equipoise by shifting the poise, the power being applied simultaneously with the movement of the poise, and continuing the operation until the test is concluded. Care must be taken that the weighing-beam is balanced before the testing is begun or the test-piece in position. Additional standard weights are supplied to suspend on the small end of the weighing-beam, as occasion requires, to balance the strain up to the full strength of the test-specimen.
This machine can be arranged to test longer specimens up to four or five feet, at extra cost. An indicator to show elasticity of specimens being tested can be added. See TRIAL CAST.