These often give trouble from the bad mechanical arrangement of the parts. The great secret in repairing them is to reduce the friction as much as possible. The resistance to the rising of the "lifter" is often enormous, and may generally be reduced very much.
The mechanism of the cuckoo clock, as usually met with, is shown in Figs. 223 to 226. There are 3 distinct movements to be considered: (1) for the production of the sounds; (2) the appearance and retirement of the bird; (3) the movement of the wings and beak.
Fig. 223 shows the first. The dotted circle a represents the position of the pin wheel set within the frame, the pins of which have to raise 3 levers. Those numbered 1 and 2 raise the bellows 6, and 3 corresponds to the ordinary hammer tail. The bellows are connected with 2 small "stopped" organ pipes d, measuring externally about 6 in. long and 1 in. square; and the "stops" are pushed in till the right note is obtained. The bellows are about 2 1/2 in. long by 1 1/2 in. wide, and are connected with the lifting levers by the wires c.
Fig. 224 shows the second movement: - f is the hoop wheel, and g the detent, which, falling in the notch, stops the running of the striking train. A is a wire lever attached to the arbor of the detent, and moves with it. i is a vertical arbor carrying a piece j at right angles, on which is fixed the bird on the perch k. A spiral spring l keeps the short lever m in proper position, to be acted upon by the long lever h. As shown in the sketch, the cuckoo would be in; when the clock strikes, the detent g rises to the edge of the hoop wheel, moving the vertical arbor i with it, and the cuckoo on the perch k opens the door by means of a wire link, which unites the perch with the door. The bird remains out until the locking-plate detent allows the detent g to again fall into the hoop wheel, when the spiral spring l causes the bird to retire and close the door.
Figs. 225, 226, show the mechanism of the cuckoo. The body of the bird is hollow, and n is a block of wood in the centre of the body, firmly fixed upon the perch k. A pin o passes through the bird and block of wood, and serves for an axis, upon which the bird works when the tail is raised. The lower part of the beak is pivoted, and has a piece of wire attached; a wire projecting from the fixed wood block n terminates in a small ring which embraces the wire of the bill. When the tail is raised, the head lowers and the beak opens. The flapping of the wings p takes place in a somewhat similar manner; they are united to the body by wire-ring joints at r, and a short wire lever is fixed in the upper edge of the wings. The end of this lever is joined by a ring joint to a fixed wire on the block. When the tail is raised, and the body moves farther from the centre of motion, the wings open; when the tail is lowered, they close. A piece of wire, fixed in the tail, is bent until exactly over one of the bellows. When the bellows are raised, they lift the wire of the tail, and thus cause the beak to open and the wings to flap.
In putting the train together, be careful to have neither of the levers resting on the pins when finished striking; and make the other parts work easily.