. Watch and clock escapements; . f our circular pallets : with oneleg of the dividers set at B we sweep through the points cad thearcs c a d. From B as a center, we continue the line B a to J, and withthe dividers set at five inches, sweep the short arc e e. From theintersection of this arc with the line B f we lay off one and a halfdegrees and draw the line B g, which establishes the extent of the 28 Watch a?id Clock Escapements. lock on the entrance pallet. It will be noticed the linear extent ofthe locking face of the entrance pallet is greater than that of theexit, although both represent
. Watch and clock escapements; . f our circular pallets : with oneleg of the dividers set at B we sweep through the points cad thearcs c a d. From B as a center, we continue the line B a to J, and withthe dividers set at five inches, sweep the short arc e e. From theintersection of this arc with the line B f we lay off one and a halfdegrees and draw the line B g, which establishes the extent of the 28 Watch a?id Clock Escapements. lock on the entrance pallet. It will be noticed the linear extent ofthe locking face of the entrance pallet is greater than that of theexit, although both represent an angle of one and a half , in practice, this discrepancy is of little importance, as thesame side-shake in banking would secure safety in either case. The fault we previously pointed out, of the generally acceptedmethod of delineating a detached lever escapement, is not as con-spicuous here as it is where the pallets are drawn with equidistant,locking faces ; that is, the inner angle of the entrance pallet (shown. Fig. 19 at s) does not have to be carried down on the arc d as far to insurea continuous pallet action of ten degrees, as with the pallets withequidistant locking faces. Still, even here we have carried theangle s down about half a degree on the arc d\ to secure a safelock on the exit pallet. THE AMOUNT OF LOCK. If we study the large drawing, where we delineate the escapewheel ten inches in diameter, it will readily be seen that although weclaim one and a half degrees lock, we really have only about onedegree, inasmuch as the curve of the peripheral line m divergesfrom the line B f, and, as a consequence, the absolute lock of thetooth C on the locking face of the entrance pallet E is but about The Detached Lever Escapement. 29 one degree. Under these conditions, if we did not extend theouter angle of the exit pallet at / down to the peripheral line m, wewould scarcely secure one-half a degree of lock. This is true ofboth pallets. We must carry the pall
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