It is quite possible that if the watch ever was closely rated it was due to counterpoise of the balance as with the present rate the poise, escapement and regulator pins were satisfactory and did not admit of further corrections that would be of advantage.
By examining the P. U. rate in second column Fig. 27, it will be found to be twelve seconds fast and then by referring to the separate P. D. (Pendant Down) rate at the bottom, it will be found to be four seconds slow. Adding these figures gives a total variation of sixteen seconds between these two positions.
| No. ...1483023.......... Make...Illinois........ | |||||||
|---|---|---|---|---|---|---|---|
| D U | - 3 | - 3 | - 1 | - 1 | P | ||
| D D | - 8 | - 5 | - 2 | - 1 | |||
| P U | + 4 | +12 | - 6 | - 4 | |||
| P R | 0 | - 4 | - 4 | + 2 | |||
| P L | - 6 | - 6 | - 7 | - 3 | |||
| - 4 | +11 | ||||||
Now if these rates were reversed and the P. D. rate was in the place of the P. U. rate the watch would have shown a very good position rate in the first five positions and the greater part of the sixteen seconds variation would have been in the pendant down position where it would be of the least disadvantage. In order to obtain this condition the collet pinning point was changed from the fast to the slow point, or from "E", Fig. 9, to "G", Fig. 11, Chapter VIII.
A pair of heavier screws were fitted to the balance to compensate for the difference in time caused by shortening the spring and the next five position test showed a variation of six seconds. A separate pendant down test proved that the pendant up and pendant down rates had been practically reversed as shown in the fourth column.
[73.]Causes of Extremely Fast Vertical Rates.
Extremely fast pendant up rates are not particularly unusual, although the causes and corrections may be widely different.
For instance, the poise and motion feature, No. 28, Chapter VII, may be responsible, or the balance may be in poise and the collet having a wide slot may cause out of poise and be responsible if the slot is located at the proper point. A defective escapement or regulator pins tightly closed may also be responsible. Should these points be found satisfactory, however, the rate is generally due to one of three causes.
1. Excessive side friction of pivots because of being too large in diameter.
2. Train wheels and pinions being of incorrect proportion and causing irregular motion and affecting the vertical positions mostly.