We shall also cut the drop down to three-quarters
of a degree. By these two economies we more than make up for the power
lost in unlocking. With highly polished ruby or sapphire pallets ten
degrees of draw is ample. But such draw must positively be ten degrees
from a neutral locking face, not an escapement drawn on paper and
called ten degrees, but when actually measured would only show eight and
a half or nine degrees.
THE PERFECTED LEVER ESCAPEMENT.
With ten degrees angular motion of the lever and one and a half degrees
lock, we should have eight and a half degrees impulse. The pith of the
problem, as regards pallet action, for the practical workman can be
embodied in the following question: What proportion of the power derived
from the twelve degrees of angular motion of the escape wheel is really
conveyed to the fork? The great leak of power as transmitted by the
lever escapement to the balance is to be found in the pallet action, and
we shall devote special attention to finding and stopping such leaks.
Pages:
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172