. Watch and clock escapements; . n of the usual cylindrical form, with two-fifths cut safety roller is three-fifths of the diameter of the pitch diameterof the jewel-pin action, as indicated by the dotted circle a. 78 Watch a?id Clock Escapements. The safety roller is shown in full outline at B, and the passinghollow at E. It will be seen that the arc of intersection embracedbetween the radial lines B c and B d is about sixty-one and a halfdegrees for the roller, but the angular extent of the passing hollowis only a little over thirty-two degrees. The passing hollow E islocated and de
. Watch and clock escapements; . n of the usual cylindrical form, with two-fifths cut safety roller is three-fifths of the diameter of the pitch diameterof the jewel-pin action, as indicated by the dotted circle a. 78 Watch a?id Clock Escapements. The safety roller is shown in full outline at B, and the passinghollow at E. It will be seen that the arc of intersection embracedbetween the radial lines B c and B d is about sixty-one and a halfdegrees for the roller, but the angular extent of the passing hollowis only a little over thirty-two degrees. The passing hollow E islocated and defined by drawing the radial line B c from the center Bthrough the intersection of radial line A i with the dotted arc 6,which represents the pitch circle of the safety roller. We will namethis intersection the point /. Now the end of the guard point Cterminates at the point /, and the passing hollow E extends on bsixteen degrees on each side of the radial line B c. The roller action is supposed to continue through thirty degrees. of angular motion of the balance staff, and is embraced on thecircle a between the radial line B k and B o. To delineate theinner face of the horn p of the fork F we draw the short arc g,from A as a center, and on said arc locate at two degrees from thecenter at B the pointy. We will designate the upper angle of theouter face of the jewel pin D as the point s and, from A as a center,sweep through this point ^ the short arc n n. Parallel with the lineA i and at the distance of half the diameter of the jewel pin D, wedraw the short lines / /, which define the inner faces of the fork. The intersection of the short line t with the arc n we will desig-nate the point r. With our dividers set to embrace the spacebetween the point r and the point f, we sweep the arc whichdefines the inner face of the prong of the fork. The space wejust made use of is practically the same as the radius of the circlea, and consequently of the same curvature. Practically, the len
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Keywords: ., bookcentury1900, bookdecade1900, bookidwatchclockes, bookyear1904
