Patent ID: 7028572

Claim:
A pitch transfer gear assembly for transmitting drive from one gear having gear teeth separated by a first pitch and another gear having gear teeth separated by a second pitch, said transfer gear assembly including: at least a first gear having a plurality of teeth; at least a second gear having a plurality of teeth different in number to the teeth of the first gear; the first and second gears having being arranged in side by side relationship so that the teeth of the first gear and the teeth of the second gear overlap one another with the teeth of the first gear and the teeth of the second gear being out of phase with one another; the first gear and the second gear being arrange for rotation independently of one another; wherein at one position about the circumference of the first and second gears, the gear teeth of the first gear and the gear teeth of the second gear are out of phase with respect to one another by a certain amount and wherein the teeth of said one gear is able to engage the transfer gear assembly by a tooth of said one gear engaging in the space between a gear tooth of the first gear and a gear tooth of the second gear; wherein at another location about the circumference of the first and second gears a further gear tooth of the first gear and a further gear tooth of the second gear have a phase relationship different to that at said one position, and a tooth of the said another gear is able to engage in the space between one of the teeth of the first gear and one of the teeth of the second gear; and wherein as drive is transmitted from the one gear via the transfer gear to the said another gear, the first gear of the transfer gear assembly advances with respect to the second gear of the transfer gear assembly.