Example.—Find the wheel for the tappets, D, for 10 picks to the round, the other wheels being: first driver, 16 teeth; first driven, 32 teeth; second driver, 20 teeth.
| 16 × 20 × 10 | = 100 wheel required |
| 32 |
To find both intermediate wheels, multiply the given driver by the picks to the round, and as the product is to the teeth in the tappet wheel, so is the required driven to the required driver.
Example.—Find the two intermediates for 10-pick tappets, if the wheel on the crank-shaft has 18 teeth, and the wheel on the tappets 120 teeth. The 18 × 10 = 180, and therefore the two required wheels must be in the proportion of 180 to 120, the former being the driven wheel. Thus a 36 driven and a 24 driver will give the required speed to the tappets. That this is correct may be seen from the following:—
| 18 × 24 | = 10 picks |
| 36 × 120 |
That the required wheels must be in this proportion will be apparent from the fact that if the wheel B has ten times the number of teeth in A, then B is revolving at the speed at which the tappets are to move; therefore if the wheel C has the same number of teeth that D has, the speed of the tappets will remain the same.
FAST-AND LOOSE-REED LOOMS.
One of the most important motions in the power loom is that by which the loom is stopped automatically when the shuttle is caught in the shed or for some reason does not enter the shuttle-box. A motion of this kind has always been considered necessary since the introduction of the power loom. If the shuttle be caught in the shed as the reed is beating up, it is obvious that great damage to the warp must result unless the loom is brought to a sudden stop or the reed thrown out. The oldest form of protector is the “stop rod.” In this the reed is fast, and if the shuttle is caught in the shed or flies out, the loom is brought to a sudden stop before beating up. [Fig. 67] will illustrate the principle of this motion. If the shuttle enters the box safely it presses back the swell S, which projects inside the box and is held there by a spring. As the swell is pressed back it raises the lever B above the frog F as the slay beats up. If the shuttle for any reason does not enter the box, the swell is not pressed back, and as the slay moves forward in beating up, the lever B catches the frog F, which is moved a little and applies the brake G, and also knocks off the loom handle H, which removes the belt on to the loose pulley. Before the application of the brake to this motion the frog was fixed to the framework of the loom, and it will easily be understood that the concussion caused many breakages. A stop rod protector was patented in 1791, but the brake was not applied until 1840 or thereabouts.
FIG. 67.