Let us analyze these drawings. A little study of Figs. [41], [42] and [43] will show that there is really only one point of difference between them and [Fig. 32], which shows the elements of the Graham, or dead beat. The sole difference is in the fact that there are no separate locking planes in the recoil, the locking and run taking place on an extension of the lifting planes. Otherwise we have the same elements in our problem and it may therefore be laid out and handled in the same manner; indeed, if we were to set off on [Fig. 32], the amount of angular motion of the pallet fork which is taken up by the run of the escape wheel teeth on the locking planes, by drawing dotted lines above the tangents, T, we should then have measured all the angles necessary to intelligently set out the recoil escapement. We should have the lock at the tangent, T, the lift and the run (or recoil) being defined by the lines on either side of it, and the length of our running and lifting planes would be found for the entering pallet by drawing a straight line between the points of the two acting teeth of the escape wheel and noting where this line cut the lines of recoil and lift. A similar line traced at right angles to this would in the same way define the limits of run and lift on the exit pallet. It will therefore be seen that our center distances for any desired angle of escapement may be found in the same way ([Fig. 28]), for either escapement, and thus the method of making the pallets for the ordinary American clock, [Fig. 43], becomes readily intelligible. The sole object of curving the pallets, as explained previously, was to decrease the butting effect of the run on the points of the teeth. This is accomplished in [Fig. 43] by straight planes on the pallets and straight sides to the teeth with 20° teeth on the escape wheel; merely inclining the plane of the entering pallet about six degrees toward the escape wheel center, thus serving all purposes, while the gain in the cost of manufacture by using straight instead of curved pallets and wheel teeth is very great.
Fig. 45. Showing the Usual Position in Cheap Clocks and the Verge Wire.
Fig. 44. Recoil with Curved Planes.
One factory in the United States is turning out 2,000,000 annually of two movements, or about 1,000,000 of each movement; there are four other larger factories and several with a less product; so it will readily be seen that any decrease in cost, however small it may be on a single movement, will run up enormously on a year’s output. Suppose the factory mentioned were enabled to save only one-eighth of a cent on one of its million movements manufactured last year, this would amount to $1,250 per year, a little over $100 per month. Thus it will be seen that close figuring on costs of production is a necessity.
