Mechanical screening device for machine-harvested sugar cane

Claim 1

In a mechanical screening device comprised of a set of spaced parallel toothed cylindrical horizontal rolls arranged on a slope and power-rotated to pass material deposited thereon up the slope, with the teeth on each roll arranged in spaced rows and the rows of teeth on each roll centered on the space between rows of teeth of the adjacent rolls, the following: a. each roller tooth has a substantially straight sweptback leading edge of about 52*; b. the rows of teeth are so located as to provide a lateral space between adjacent teeth of about 6 inches; c. the roll spacing provides a space of about 12 inches between adjacent rolls; d. the mechanical screening device also comprises means to drive the rolls at tooth tip speed of at least 350 feet per minute with each roll after the first one to three rolls rotated at a tooth tip speed which is about 15 percent higher than the next preceding roll; and e. the effective length of the mechanical screening device is at least 21 feet; whereby as a mat of dirty machine-harvested sugar cane is fed onto the lower end of the mechanical screening device, sugar cane stalks will be disentangled, extraneous material will be loosened from the cane stalks removing large rocks from the mat and all but rocks will progressively pass through the screening device, being spread out in length and thus separated farther because of the progressive increase in speed of the toothed rolls.