Fig. 86.
The clicks for maintaining powers should not be short, and the planting should be done so that lines drawn from the barrel center to the click points and from the click centers to the points, will form an obtuse angle, like B, [Fig. 86], giving a tendency for the ratchet tooth to draw the click towards the barrel center. The clicks should be nicely formed, hardened and tempered and polished all over with emery. Long, thin springs will be needed to keep the winding clicks up to the ratchet teeth. The ratchet wheel must run freely on the barrel arbor, being carried round by the clicks while the clock is going, and standing still while the weight is being wound up. It is retained at this time by a long detent click mounted on an arbor having its pivots fitted to holes in the clock frame. The same remark as to planting applies to this click as well as the others, and to all clicks having similar objects; but as this click has its own weight to cause it to fall no spring is required. To prevent it lying heavily on the wheel, causing wear, friction and a diminution of driving power, it is as well to have it made light. There is no absolute utility in fixing the click to its collet with screws, but if done, it can be taken off to be polished, and the appearance will be more workmanlike. This click should have its point hardened and tempered, as there is considerable wear on it.
Fig. 87.
If the great wheel has spokes the best form for the two springs for keeping the train going whilst being wound is that of the letter U, as shown to the left of [Fig. 84], one end enlarged for the screw and steady pin and the blade tapering all along towards the end which is free. The springs may be made straight and bent to the form while soft, then hardened and tempered to a full blue. They are best when as large as the space between two arms of the main wheel will allow. When screwed on the large ratchet the backs of both should bear exactly against the respective arms of the mainwheel, and a pair of pins is put in the ratchet, so that any opposite pair of the mainwheel arms may rest upon them when the springs are set up by the clock weight. The strength of the springs can be adjusted by trial, reducing them till the weight of the clock sets them up easily to the banking pins.
There are two methods of keeping the loose wheels against the end of the barrel, while allowing them to turn freely during winding; one is a sliding plate with a keyhole slot, [Fig. 87], to slip in a groove on the arbor, as is generally adopted in such house clocks as have fuzees, as well as on the barrels of old-fashioned weight clocks; the other is a collet exactly the same as on watch fuzees. They are both sufficiently effective, but perhaps the latter is the best of the two, because the collet may be fitted on the arbor with a pipe, and being turned true on the broad inside face, gives a larger and steadier surface for the mainwheel to work against, whereas the former only has a small bearing on the shoulder of the small groove in the arbor, which fitting is liable to wear and allow the main and the other loose wheel to wobble sideways, displacing the contact with the detent click and causing the mainwheel to touch the collet of the center wheel if very near together; so, on the whole, a collet, as on a watch fuzee, seems the better arrangement, where there is plenty of room for it on the arbor.
There is an older form of maintaining power which is sometimes met with in tower clocks and which is sometimes imitated on a small scale by jewelers who are using a cheap regulator and wish to add a maintaining power where there is no room between the barrel and plates for the ratchets and great wheel.
The maintaining power, [Fig. 88], consists of a shaft, A, a straight lever, B, a segment of a pinion, C, a curved, double lever, D, a weight, E. The shaft, A, slides endwise to engage the teeth of the pinion segment with the teeth of the great wheel. No. 2, the straight lever has a handle at both ends to assist in throwing the pinion out or in and a shield at the outer end to cover the end of the winding shaft, No. 3, when the key is not on it.