. Modern mechanism, exhibiting the latest progress in machines, motors, and the transmission of power, being a supplementary volume to Appletons' cyclopaedia of applied mechanics . a insulation is used between and at the side of the bars. The slot is iV in. deeper thanthe bars, so that it leaves a space below the same to insulatethem from the iron. There iire 74 bars in the commutator,each connector on one end of the armature leading to a brushes nuvy be placed 00° or 180° apart. On the ma-chine shown, they have been placed 00° apart, but, all thingsconsidered. 1S0° is preferable. The
. Modern mechanism, exhibiting the latest progress in machines, motors, and the transmission of power, being a supplementary volume to Appletons' cyclopaedia of applied mechanics . a insulation is used between and at the side of the bars. The slot is iV in. deeper thanthe bars, so that it leaves a space below the same to insulatethem from the iron. There iire 74 bars in the commutator,each connector on one end of the armature leading to a brushes nuvy be placed 00° or 180° apart. On the ma-chine shown, they have been placed 00° apart, but, all thingsconsidered. 1S0° is preferable. The iron of tlie armature runs in such close proximity tothe field-magnets (the clearance necessary for rotation beingthe only gap in the magnetic circuit) that the expenditureof energy on the field-magnets is very small, being less than1-,% per cent of the total when the niachine is fully nnist be conceded to be a remarkably good result whenthe slow speed of the machine is taken into consideration. Tlie following table gives the results of a test of the ma-chine illustrated, made by Dr. W. E. Geyer and D. G. Jacobus, M K., at the Stevens Instituteof Technologv:. Fig. 76.—Connectors. NUMBER OF TEST. Speed of annatnre, 1revolutions per Amp4re«. Efficiency, pei cent. 1 .556-6 1 547-a 540-3 581-4 5050-151-54551 84-1 2 3 84-583-9 4 86-3 .5 86 The base of the machine is .31 X 31 in., and it stands 26 in. high. The diameter of thearmature is 12J in., and the length of its core 0 in. The following table gives the weights ofiron and cojjper employed in its construction: Lbs Lbs Field—Iron, soft Norway <^40 cast ? 2H • Brass 23 • Wire Bed, standards, bolts, etc Bnish-iiolder, brass Armature—Iron (slieet) 153 cast end-plates 142 Steel shaft 36 391-5 108-0 235-3 10-7
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Keywords: ., bookcentury1800, bookdecade189, booksubjectmechanicalengineering
