GB1265438A - - Google Patents

Abstract

1,265,438. Photo electric plant-row thinner. EVERSHAM MFG. CO. 10 April, 1970, No. 17238/70. Heading A1B. A photo-electrically controlled plant-row thinning - implement removes, by cutting through the roots, plant whose stems have a thickness less than a pre-set value. The cutting elements oscillate about a longitudinal axis, parallel to the plant row andto the direction of travel of the implement which is from left to right in Fig. 2, at a speed of, say, 2 m.p.h. A transverse tool beam 12 carries several frame beams 22 each of which is aligned with the plant row. Fixed to each beam 22 is a channel-shaped mounting bracket 20 which supports a disc-weeder 78 and a longitudinally telescoping photocell-supporting arm 30. The angle of the arm 30 is adjustable by means of springs 33, 35 and rod 32. From the rear end of the arm 30 depends a row-spanning yokebar 39 on the opposite arms of which a lightsource 43 and the receiving photocell assembly are mounted. Supported on the light-shielding plates 46, which are attached to the yoke bar 39, are two discs 49 which gently raise the leaves of the plant so that the light beam intercepts only the stem of each plant. The electronic control box 73 processes the photocell output and controls the flow of compressed air through a four-way solenoid-actuated airvalve assembly 65 in order to operate a pair of thinning knives which have blades 52 and 53 mounted on arms 54 and 55 which oscillate, rigidly attached to each other, on a knife shaft 56 which is attached to the frame-beam 22 by the bearing-plates 57. A below standard plant stem is cut as in Fig. 10 by the blade running under the surface of the soil. When the light beam is interrupted by a plant stem for a sufficiently great length of time the knife assembly swings clockwise about the shaft 56 with the result that the blade 52, which was approaching the plant stem, is swung clear to the left while the blade 53 enters the soil ahead of the plant leaving the plant in an uncut gap of a length essentially equal to the spacing of the knife arms 54 and 55 on the shaft 56. The light beam is now automatically extinguished and the knife blade 53 cuts through the soil for a pre-set distance, regardless of any plants in its path, after which the blades swing back in an anticlockwise sense, the light beam is restored and the thinning cycle may repeat.