User:Sombir kundu

Agricultural engineering : Harvesting and Threshing equipment - Harvesting - It is the operation of cutting, picking, digging or a combination of these operations for removing the crop from under the ground or above the ground or the useful part fruits from the plants. Harvesting action can be done by four ways - 1. Slicing action with a sharp tool. 2. Tearing action with a rough serrated edge. 3. High velocity single element impact with sharp or dull edge. 4. Two element scissors type action. Principle of cutting of a crop : A crop is cut by shearing action of cutting elements. During the process of shearing, some bending and compression also take place. In practice, two opposed shearing elements meet and pass each other with little or no clearance between them. Either one or both of the elements may be moving to produce motion. The motion may be of three types : 1. Linear motion 2. Reciprocating motion 3. Rotary motion If ground is surface, single cutting element is sufficient to perform the job. The cutting element may be moving or stationary with respect to the machine.