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44

FIG. 29.

T

CAMBRIDGE SCIENTIFIC INSTRUMENT COUP

The machine is driven by means of the three-speed cone pulley A. At one end of the spindle carrying this cone pulley is a crank B, which serves to give a circular motion to the end of a rod C. This rod is also supported at some point in its length by a roller D, the framework supporting which can be fixed at various distances away from the crank B. The other end of the rod C therefore describes an irregular elliptical path, the amplitude of which in a vertical direction depends upon the position of the roller D. This end of the rod is bent at right angles, case hardened, and arranged to engage during its upward path with a hammer head E weighing 42 lbs. (2’0 kilos.). This hammer head E is supported by a lever F, which is hinged at G. As the end of the lifting rod C ascends it engages with and lifts the hammer E ; when it reaches the top of its path it moves forward and disengages with the hammer, allowing it to fall freely on to the specimen H, this cycle being repeated about 100 times a minute. The scale M shows directly the vertical drop of the hammer, which may be adjusted as desired up to a maximum of 32 ins. (90 mm.).

The specimen under test H is usually about 2 in. (12:5 mm.) in diameter, with a groove turned at its centre to ensure its fracture there, and is supported on knife edges 42 ins. (114 mm.) apart. The knife edges are cut slightly hollow, and a spring K holds one end of the specimen in place. The other end is held in a chuck, which is hinged in such a manner that it does not take any portion of the hammer blow, all of which comes on the knife edges.

Le texte affiché peut comporter un certain nombre d'erreurs. En effet, le mode texte de ce document a été généré de façon automatique par un programme de reconnaissance optique de caractères (OCR). Le taux de reconnaissance estimé pour cette page est de 99,21 %.

La langue de reconnaissance de l'OCR est l'Anglais.