This matter is of so much importance
that we will give further explanation. Suppose we bend the detent spring
_h_ so it is curved to the dotted line _t_, Fig. 136, and then the foot
_F_ would assume the position indicated at the dotted line _r_. We next
imagine the foot _F_ to be put in the position shown by the full lines,
the spring _h_ will become straight again and in perfect shape to resist
the thrust of the escape wheel.
Little "ways and methods" like the above have long been known to the
trade, but for some reason are never mentioned in our text books. A
detent spring 2/1000" thick and 80/1000" wide will stand the thrust for
any well-constructed marine chronometer in existence, and yet it will
not require half a pennyweight to deflect it one-fourth of an inch. It
is a good rule to make the length of the detent from the foot _F_ to the
center of the locking jewel pipe _j_ equal to the diameter of the escape
wheel, and the length of the detent spring _h_ two-sevenths of this
distance.
Pages:
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267