Om Materialprøvningens Udvikling i Norden
Og om Statsprøveanstaltens Virksomhed

 127 tion of the fork as the greatest allowable and arranged a special measuring instrument for the purpose of quickly determining whether this is surpassed or not. Among the 370 forks tested up to the 1st of Juli 1909, altogether 8 forks did not stand this impact-bending-test. After having been subjected to this test the front-forks were subjected to a tensile test in order to ascertain whether during the impact test a hidden fissure had appeared or a soldering been broken. In the tensile test apparatus the pulling force of 500 kg is exer- cised in turning by means of a very long lever an axle on which a chain is hereby wound up. This latter then pulls a nut on the steering column of the front-fork some iron-bars stuck down into the concrete-floor resisting either against the crown or against a transverse bar through the axle holes at the ends of the sheaths, namely if the holes have a closed circumference. A dynamometer is inserted between chain and the nut on the steering-column. By means of a special coupling piece the dynamometer can easily be coupled to the nut and separated after the test. All forks tested have gone through the pulling test. Except a single one only new front-forks were tested, and in none of these the test has occasioned any fracture. It is therefore not quite possible to judge of the value of the test, as the test would presumably be best suited for ascertaining a beginning fracture in used front forks. There are, for the rest, now reinforces to be put on within the steering-column and whilst the test may be worthy of recom- mendation to vendors of cycles on purchasing lots of front- forks the purchase of a reinforce will presumably be preferable to private persons in spite of the somewhat greater expense. The Danish standard specifications for cast-iron differing from the German, it being claimed in Germany that a bar with a distance of 1 m between the supports and a height and breadth of 30 mm shall be able to support a weight in the middle of 450 kg which according to the usual bending formula corresponds with a modulus of rupture of 25 kg pr. sq. mm., whilst it is clai- med in Denmark that a bar with the same distance between the supports, but of a height and breadth of 25 mm shall be able to support a weight in the middle of 300 kg which corresponds with 28,8 kg pr. sq. mm, it may perhaps be of some interest to see