door unit for a device for the holds of below the ground surface grown crop material, preferably potato

摘要

1498109 Root crop separators ROOT HARVESTERS Ltd 12 Feb 1976 [8 April 1975] 14270/75 Heading B2H A finger unit for a root crop separator comprises a housing 4, a finger 6 pivotably mounted at 56 in the housing and fitting across a chamber therein with a portion 64 of the finger cooperating with a piston 32, and an inlet for compressed air to the chamber, the arrangement being such that flow of air out of the chamber is confined to clearances between the finger and the' housing. In use the finger portion 6 is normally inclined at 45‹, it being held in this position by means of compressed air supplied to the space above the piston 32 through a passage 44. When an X-ray sensor detects the presence of a stone or clod of soil in a stream of falling material comprising potatoes, stones and earth, the finger is moved out of the path of the falling stream to the position shown. On receipt of the signal from the X-ray sensor, a solenoid valve 8 disconnects the passage 44 from the compressed air manifold 10 and brings it into communication with a passage 48 leading to the chamber so that the air is exhausted from above the piston 32. This enables a spring-operated piston 36 to move the finger 6 to the retracted position shown. The compressed air may contain a lubricant.