FIG. 65.
If the wheel on the crank-shaft A contains 45 teeth, and the wheel B 90 teeth, C 40 teeth, and E 60 teeth, the tappet-shaft S will be making one revolution for three revolutions of the crank-shaft; therefore these wheels will do for three-end twill tappets. This may be proved by multiplying the drivers together and the drivens together, and dividing one by the other, thus—
| 90 × 60 | = 3 |
| 45 × 40 |
It is usual to place two or three wheels on the bottom shaft of the loom, so that any one of them may be geared into the carrier wheel D, each giving the required speed for different tappets. If a 40 wheel, a 30 wheel, and a 24 wheel are placed on the bottom shaft in such a manner that they can be moved along the shaft and any one of them be geared into the carrier wheel, any 3, 4, or 5 pick tappets can be driven with these wheels. We have seen that a 40 wheel at C gives three picks to the round.
Suppose the 30 wheel at C is geared into the carrier wheel, we get—
| drivens | 90 × 60 | = 4 |
| drivers | 45 × 30 |
or the relative speed of the tappets and crank-shaft are as 1:4; therefore these wheels may be used for any tappets with four picks to the round.
If the 24 wheel is at C, we get:
| drivens | 90 × 60 | = 5 |
| drivers | 45 × 24 |