The main working part of the Roller Valley machine is a horizontal rubber roller or plastic roller which is bonded on a cast iron cylinder or a glue layer of a suit. Two rollers axis is located in the same horizontal plane or slightly height difference, with different rotational speed opposite rotation, one of the roll position fixed, another roll can be moved, so that the rolling distance between the two rollers can be adjusted.
The difference between two rollers is $number. 2 m/s and the line speed is not more than 30 m/s. The paddy passes through the board (or passes through the feeding roller and the plank) in the cots entire length on evenly feeds between two rollers, the equal diameter roller with different line speed reverse turns, through presses the weight of the mound the pressure causes through the roller between the paddy to be squeezed and rubs tore. Due to the two-roll extrusion and the two-roll speed difference produced by the rubbing action, most of the paddy rice to the shelling, into the chaff separation device, and then through the suction tuyere to $number m/s wind speed suction to remove the rice husk. After separating the grains from the rice husk, the coarse mixture is discharged from the discharge plate. The rolling distance adjusting mechanism has two kinds of constant pressure regulation and fixed distance adjustment. Constant pressure regulation can be carried out by air pressure, hydraulic pressure or thallium, in which the pressure thallium-type automatic roller (rolling distance adjustment) is China's first development in the 1960s. In order to maintain the correct line speed of the two cots, China has also developed a gear transmission and triangular belt combination of transmission mode. Plastic Roller Valley Machine shelling rate is high, brown rice surface smooth, rice less, but in high temperature when cots wear fast, brown rice burst waist more, production cost is higher.