Machine drawing; a practical guide to the standard methods of graphical representation of machines, including complete detail drawings of a duplex pump and of a direct-current generator . M- Fig. 115. Layout for Annular Gears Hence, to find the addendum and dedendum in the present case, take the reciprocal of 4, which is J. The clearance, being J the addendum, is equal to J of \ = ^V-If the student tries to follow the above description by actually drawing these gears, it will be found necessary to draw them to about 3 times their actual size in order to bring out the points clearly. That is to
Machine drawing; a practical guide to the standard methods of graphical representation of machines, including complete detail drawings of a duplex pump and of a direct-current generator . M- Fig. 115. Layout for Annular Gears Hence, to find the addendum and dedendum in the present case, take the reciprocal of 4, which is J. The clearance, being J the addendum, is equal to J of \ = ^V-If the student tries to follow the above description by actually drawing these gears, it will be found necessary to draw them to about 3 times their actual size in order to bring out the points clearly. That is to say, the pitch circles should be made 9 and 12; the MACHINE DRAWING 3 // addendum and dedendum f; the clearance ; 141the numbers of teeth, of course, remaining 12 and 16. ANNULAR GEARS An annular gear is a ring with teeth on the inside of it. Fig. 115shows such a gear, with center at A, meshing with its pinion. The. Fig. 116. Construction for Epicycloidal Rack and Pinion method of drawing such a pair of gears is similar to that just de-scribed for two spur gears. Here the circle C, by rolling on the insideof the pitch circle of A, generates the faces of the teeth on A; and thecircle D, by rolling on the outside of the pitch circle of A, generates 142 MACHINE DRAWING the flanks of the teeth on A. The shape of the teeth of the pinionin the figure is found with the same describing circles placed at Cand D to avoid confusing the lines. In designing an annular gear and pinion, the diameter of thegear must never be so small that the distance from center A to centerB shall be less than the sum of the radii of the two describing this should be the case, the teeth would interfere with each other. RACK AND PINION A rack is a gear whose pitch line is a straight line instead of acircle. Fig. 116 shows an epicycloidal rack in gear with a 16-toothpinion. The describing circles are of the same size i
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Keywords: ., bookcentury1900, bookdecade1910, bookpublis, booksubjectmachinery
