Plate CCCVI. Fig. 3. represents that part of a repeater which is called the dial or motion work. It is seen in the instant where the button or pendant is just pushed home to make it repeat. In first taking off the hands, and then the screw which fixes the dial of repeating watches, we will see the same mechanism that this Figure presents. This is the kind of repeating motion work most generally adopted ; it is solid, and of easy execution. P is the ring or bow to which the pendant shank or push er is attached, and this enters into the socket 0 of the watch case, and moves within it its whole length, in tending towards the centre. It carries the piece 12, which is of steel, and fixed in the pendant shank, both compos ing the pusher ; the under side is filed fiat. A plate of steel fixed to the case inside, prevents it from turning round about, and permits it to move lengthwise only. The end part of the steel in the pusher is formed so that it cannot come out of the case socket, this being also pre vented by the small steel plate.
The end of the piece p acts on the heel t of the rack CC, whose centre of motion is at y, and at whose extre mity c, is fixed one end of the chain s s. The other end keeps hold of the circumference of a pulley A, put by a square on the prolonged arbor of the first wheel of the runners. This chain passes over a second pulley B.
If, then, we push the pusher P, the end c of the rack will describe a certain space, and, by means of the chain s, will cause the pullies A, B to turn. The ratchet R (Fig. 4.) will also retrograde, until the arm b of the rack comes upon the snail L ; then the main spring of the repetition bringing back the ratchet, and the pieces which it carries, the arm in will present itself to the teeth of the ratchet, and the hammer M will strike the hours, of which the quantity depends on the step of the snail, which is presented to the arm b.
In order to have a better idea of the effect and disposi tion of this repetition, it is only necessary to look at Fig. 4. where the rack y c is seen in perspective ; the hour snail L, and the star wheel E ; the pullies A and B, the ratchet R, the wheel a, the part of raising inn of the hour hammer ; and these are the principal parts of a repetition, which are drawn as if they were in action.
The snail L is fixed to the star E by means of two screws ; they both turn on the pivot formed from the screw V, carried by the all ur nothing piece T R, move able on its centre T ; the all or nothing piece forms with the plate a sort of frame, in which the star and hour snail turn —Let us now see how the quarters are repeated.
Besides the hour hammer M, there is another N, (Plate CCCVI. Fig. 1.), whose arbor of pivot comes up within the motion work, and carries the piece 5. 6 (Plate CCCVI. Figs. 3, 4.) The prolonged pivot of the hour or great hammer passes also within the motion work, and carries the small arm q : these pieces .5, 6 and ry, serve to make the quarters strike by double blows. This is the effect of the quarter rack Q, which has teeth at the ends F and G, that act on the pieces q, 6, and cause the hammers to strike. This piece or rack Q is carried about by the arm k, which the arbor of the ratchet R has on it, by a square above the pulley A, in such a manlier, that when the hours are repeated, the arm k acts on the pin G fixed in the quarter rack, and obliges it to turn and raise the arms q and 6, and consequently the hammers.
The number of quarters which the hammers must strike is determined by the quarter snail N, according to the depth of the steps /2, I, 2, or 3, which it presents : the quarter rack Q. pressed by the spring D, retrogrades ; and the teeth of the rack engage more or less with the arms ry, 6, which get also a retrograde motion, and are brought back by the springs 10 and 9 : The arm k bring ing back the quarter rack, its arm m acts on the extremity R of the all or nothing TR, the opening of which at x, traversing against a stud fixed to the plate, allows R to describe a small space : the arm in, coming to the ex tremity of R, this last pressed by the spring i x, is made to return into its place, so that the arm m rests on the end R, and by this the quarter rack cannot fall or retrograde, unless the all or nothing piece is pushed aside. The arm u, carried by the quarter rack, serves to overturn or set aside the raising piece in, (Fig. 4.) (which is moveable on the arbor of the hour hammer,) whose pin I, comes up within the motion work ; so that when even the hours and quarters are repeated, the quarter rack still continues to move a little way, and the arm u turns aside the raising piece ,n, by means of the pin 1, which comes within the motion work, and by this it is put from having any holding with the ratchet R, so long as the all or nothing TR does not allow the quarter rack to retrograde or fall ; which can only happen in the case when, having pushed borne the pendant against the snail, the arm b of the rack CC presses the snail, and makes it describe a small space, at the extremity R of the all or nothing : then the quarter rack will tall and disengage the bees or lifting pieces, and the hammers will strike the hours and quarters, given by the snails L and N.