pitch line

When two gears of equal size mesh together, the pitch line, or the pitch circle, as it isp.

You will note, from the above illustration, that the actual pitch line should meet the junction of the chord line and top line.

The pitch line is then drawn at a radius of 1.606 of the pitch from the worm axis.

The mortise spur-wheels have a diameter of 22 feet at the pitch line, with two rows of teeth, each 15 inches face.

The teeth are designated for measurement by the pitch; the height or depth above and below pitch line; and the thickness.