"
The chronometer escapement consists of four chief or principal parts,
viz.: The escape wheel, a portion of which is shown at _A_; the impulse
roller _B_; unlocking or discharging roller _C_, and the detent _D_.
These principal parts are made up of sub-parts: thus, the escape wheel
is composed of arms, teeth, recess and collet, the recess being the
portion of the escape wheel sunk, to enable us to get wide teeth actions
on the impulse pallet. The collet is a brass bush on which the wheel is
set to afford better support to the escape wheel than could be obtained
by the thinned wheel if driven directly on the pinion arbor. The impulse
roller is composed of a cylindrical steel collet _B_, the impulse pallet
_d_ (some call it the impulse stone), the safety recess _b b_. The
diameter of the impulse collet is usually one-half that of the escape
wheel. This impulse roller is staked directly on the balance staff, and
its perfection of position assured by resting against the foot of the
shoulder to which the balance is secured.
Pages:
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262