Patent GB-709001-A (GB)
Title: An improved apparatus for separating stones and the like from root crops
IPC: A01D33/04
Filed: 1950-03-13
Abstract: 709,001. Harvesting root-crops. SMITH, T. S. March 13, 1951 (March 13, 1950], No. 6222/50. Class 6 (3). [Also in Groups II, XXX and XXXVI] An apparatus for separating stones and earth from root crops comprises a conveyer for advancing crop, stones and earth along a predetermined path, a pair of electrodes disposed in said path and adapted to pierce the skin of a root, and root ejecting means which are connected in the electric circuit of said electrodes and when said circuit is completed by the penetration of the electrodes into a root are actuated to eject a root from said path. As shown in Figs. 1 and 3, a series of transversely extending bars 2 are attached to a pair of parallel, spaced endless belts or chains which are driven by means of sprockets 3. Terminal strips 4, 5, on opposite sides of the conveyer carry a plurality of electric brushes 6, 7, respectively, adjacent bars 2 being contacted by brushes on opposite sides of the conveyer. The brushes 7 are each connected by a lead 8', 8<SP>3</SP>, to a separate electrically operated air valve 9', 9<SP>2</SP>, and the brushes 6 are connected by a common lead 10 to an electric power supply, the other side of which is connected by a lead 11 to the air valves. The valves are opened when their associated brushes are connected by an electrically conducting object lying across a pair of bars 2, each valve being provided with a nozzle 12 which directs a jet of air upwardly from a compressed air supply. The bars 2 are provided with sharp edged rings, Figs. 4 and 5 (not shown), to pierce the skin of the potato and complete the circuit of a low voltage relay which operates the valve. The conveyer is provided with a number of passageways 15, 16 formed by means of guide plates 17, 18, the entrance to each passageway 16 being closed so that the whole of the material must enter the passageways 15. When the electrical circuit of an air valve 9' is closed by a root, the root is ejected upwardly from its passageway 15 and deflected sideways into the adjacent passageway 16. Each passageway 15 is provided with three valves spaced along the length of the conveyer. At the end of the conveyer the roots drop on a side delivery conveyer 19 and the stones are diverted to another side delivery conveyer 20. A number of soft rubber loaded rollers are fitted in front of each nozzle 12 to press down lightly on the material to ensure the penetration of the contacts, and a rotary brush may be provided on the underside of the conveyer to scour the contact rings as they pass thereunder. Potatoes may be graded into sizes before they reach the passageways 15, by means of a rotary brush 21 which is disposed above a picking conveyer 22 at an angle to the direction of travel of the roots and inclined to the horizontal. In a modification, Figs. 6 and 8 (not shown), a plurality of spaced parallel belts 23 of V-section pass over rollers 24. The air nozzles 25 are provided with two metal discs 26, Fig. 9, moulded into an insulated wheel 27 to provide a pair of rotatable electric contacts, the air from the nozzle 25 being directed up the sides of the discs 26. Carbon brushes 30 provide an electrical connection to the metal discs. Guide plates 17 and 18 deflect the roots into separate passageways.