. A textbook on electric lighting and railways. International correspondence schools, Scranton, Pa. v. 1-3, 5 . edand it would be almost impossible to replace a brush if themotor were hot. Another point to bear in mind is that somemotors have their pole pieces on the diagonal, while others 74 ELFXTRIC RAILWAYS. 24 have them on the vertical and horizontal, with the resultthat on the former type, the brushes are set on the commu-tator at points opposite the centers of the pole pieces insteadof being set at points midway between them correspondingto the position of the neutral line. This is neces
. A textbook on electric lighting and railways. International correspondence schools, Scranton, Pa. v. 1-3, 5 . edand it would be almost impossible to replace a brush if themotor were hot. Another point to bear in mind is that somemotors have their pole pieces on the diagonal, while others 74 ELFXTRIC RAILWAYS. 24 have them on the vertical and horizontal, with the resultthat on the former type, the brushes are set on the commu-tator at points opposite the centers of the pole pieces insteadof being set at points midway between them correspondingto the position of the neutral line. This is necessary fromthe fact that if the brushes were set at the neutral line, onewould be on top and the other would be down on one side,»vhere it would ])e hard to get at. 82. Connections for a 99-Coil Arniatxxre.—Fig. 54shows an armature having 99 coils and slots, its pole piecesbeing horizontal. The coil for this armature would haveone short lead and one long one, and would be of such av/idth that one side could drop into slot 1 and the other sideinto slot £<3; the short lead would then go straight down to. the commutator bar immediately in line with it and thelong lead would go to the bar as nearly diametrically oppo-site as possible. This would be bar 50. The next coilwould drop into slots 2 and ;?7 and its leads would go tobars 2 and 51. This is a rule that holds good on any arma-ture having 99 slots and 99 coils where the four poles are on 24 ELECTRIC RAILWAYS. 75 the horizontal and vertical, as, for example, on the G. or 1,200 motors. To make it hold yood on armatureshaving 99 coils, 99 bars, hut only 33 slots, it is only neces-sary to count off as if each coil had its own slot or as ifthere were no slots at all. Vor instaiu-e, suppose there areonly 3.) slots; then, one sitle of coils /, J, and ./ will he inslot 1: 4, -7, and ! in slot -■; 7, in slot -/; and so on,so that the other sides of coils J, J, and ■/, which formerlyfell into slots 2(1, 27, and 28, when t
Size: 1652px × 1512px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectelectri, bookyear1901
