Farm Machinery and Equipment-II: LESSON 1.HARVESTING AND THRESHING TERMINOLOGY

LESSON 1.HARVESTING AND THRESHING TERMINOLOGY

Harvesting and threshing is an important operation in the farming. This can be done either manually or with the help of power operated machinery. Harvesting of field crops continues to be one of the most labour intensive operations in agricultural production system. Manual harvesting with different hand tools continues to be dominant, which takes 170-200 man-hours to harvest one hectare of paddy crop. Due to high labour demand at the time of harvesting, the operation continues for weeks together, resulting in over drying of crops in the field causes grain losses to the extent of 5 to 15 percent and even results in loss of crop due to untimely rain during harvesting. Higher shattering losses occur while harvesting crops like wheat, barley and gram in over dried conditions. Harvesting of crops like maize, sorghum and arhar is done at relatively low moisture content. The crop stacks are thick and woody and the hand sickle is adequate tool used for harvesting. For other conditions, a hand chopper is sometimes also employed. Now mechanized harvesting devices such as reapers, combine harvesters etc. are being used for harvesting these crops.

Harvesting and threshing terminology

Combine: a machine designed for harvesting, threshing, separating, cleaning and collecting grain while moving through the standing crop. Bagging arrangement may be provided with a pick-up attachment. It may be used for handling crop that has been swathed. It may be self-propelled type or tractor operated type.
Self-propelled combine: a combine on which an engine of suitable power rating is mounted to serve as source of power, this may be wheeled type or track-laying type.
Wheeled Combine: A combine in which the pneumatic wheels are used.
Track-laying combine: A combine fitted with full or half tracks instead of pneumatic wheels.
Tractor operated combine: A combine which requires a tractor of suitable power rating to serve as a source of power for its working. It may be trailed type or side mounted type.
Header: The portion of the combine comprising the mechanisms for gathering the crop.
Gathering width: The distance between the centerlines of the outermost divider points expressed in millimeters. Where adjustable dividers are used the maximum and minimum dimensions shall be stated.
Grain header width: The distance between the side sheets of the header measured immediately above the forward tips of the sickle sections. Width shall be expressed in millimeters.
Corn Header width: The average distance between the centre lines of adjacent picking units multiplied by the number of units. Where the header width is adjustable, maximum and minimum di8mensions shall be stated. Width shall be stated in millimeters and the number of picking units shall be stated.
Knife or Sickle: The reciprocating component of the header fpr cutting the crop.
Knife or Sickle Frequency: The number of cycles which the sickle makes in a given period of time. One cycle is the full movement of the sickle in one direction and its return to the starting point. Frequency shall be expressed in whole cycles/minute.
Sickle Stroke: The distance that a point on the sickle travels with respect to the centre line of a guard n one half cycles. Stroke shall be expressed in millimeters.
Knife Registration: The alignment of centre line of knife section with the centre line of guard.
Pick up: A device for gathering a crop from a window.
Peg Drum: A cylinder having rows of spikes or pegs.
Rasp Drum: A cylinder having bar with serrations.
Cylinder Diameter: The diameter of the circle generated by the outermost point of the cylinder threshing elements, expressed in millimeters.
Cylinder Width: The length of the cylinder bar measured parallel to the cylinder axis, expressed in millimeters.
Concave Arc: A means of defining the width of a concave in degrees. This shall be measured from the front to the first bar to the rear of the last bar and in relation to the centre of the cylinder
Cylinder and Concave Clearance: The gap between the tip of the cylinder to the inner surface of the concave expressed in millimeters. The minimum and maximum clearance in a particular setting and adjustment range for both the front and the rear side of the concave shall be stated.
Concave Width: The minimum distance between the two panels of the combine in which the concave is mounted, expressed in millimeters.
Concave Length: The distance from the front of the first bar to rear of the last bar, measured around the contour formed by the inner surfaces of the concave bars, expressed in millimeters.
Concave Area: The product of the concave width and concave length expressed in square millimeters.
Concave grate area: That portion of the concave area which is permeable for separation. The area shall be calculated using the outside dimensions of the permeable surface and be expressed in square millimeter.
Concave grate extension: A permeable element approximately concentric with the cylinder and generally forming an extension of the concave contour.
Concave grate extension area: The product of concave ratio extension length and concave width expressed in square millimeters.
Transition grate: A permeable element to provide transition from the concave or concave grate extension to the straw walkers or rack.
Transition grate length: The contour length of the upper surface of the transition grate, ex[pressed in millimeters.
Transition grate area: The product of the transition grate length and the concave width, expressed in square millimeters.
Straw walker or straw rack area: The product of thee straight length and the inside width of the separator side structure immediately adjacent to the straw walkers or rack, expressed in square millimeters. Where walker extensions are used in the standard specifications of the machine.
Straw raddle area: The product of the raddle length and the exposed width of the raddle, expressed in square millimeters.
Shoe: The oscillating structure which supports the cleaning sieve of sieves and which may also support the chaffer sieve and chaffer sieve extension.
Sieve cleaning areas of the shoe: The chaffer sieve, intermediate sieve, cleaning sieve and extensions to them. The area of each shall be calculated using the outside dimensions of the permeable surface, and shall be expressed in square millimeters.
Pneumatic cleaning areas: Where chaff is removed by aerodynamic means alone. These areas shall be calculated as the product of the width and depth of the air stream at the point of contact of the air with the crop material. The depth shall be measured perpendicular to the direction of the air flow. The area shall be expressed in square millimeters.
Other cleaning areas: Dirt screens, re-cleaners and other auxiliary cleaning devices. These areas shall be specified.
Cleaning area total: The sum of the area of each chaffer, chaffer extension, cleaning sieve (s) and sieve extension (s), if any, obtained by using the outside dimensions of the sievable surface expressed in square millimeters.
Component areas: For purposes of combine specification, the areas defined in 28, 29, 31, 34, 35, 36, 38, 39, and 40 shall be listed individually and should not be used singly or in combination as a measure of machine performance or capacity.
Header loss: The loss of grains and ear heads being shed and left over on the ground as a result of operation of cutter bar and header unit.
Non-collectable loss: The loss of grains and ear heads being shed and left over on the ground as a result of operation of cutter bar and header unit.
Pre-harvest loss: The loss of grain or ear heads from the standing crop prior to the operation of harvesting machine in the field.
Cylinder loss: The loss of unthreshed heads and damaged grains passing out of threshing cylinder.
Rack loss: The threshed grains passing out in the straw.
Shoe loss: The threshed grains blown or carried out with the chaff.
Engine displacement: Engine displacement shall be expressed in cubic centimeters to the nearest whole number.
Turning radius: The distance from the turning center to the center of tire contact of the wheel describing the largest circle while the vehicle is executing its shortest turn without turning brakes in operation. The wheel base and guide wheel tread width shall be stated. Turning radius shall be expressed in whole centimeters.
Clearance radius: The distance from the turning centre to the outermost point of the combine executing its shortest turn without brakes in operation. If equipment options on attachment affect this dimension, such equipment shall be specified. The wheel base and guide wheel tread width shall be same as in turning radius. Clearance radius shall be expressed in whole centimeters.
Combine weight: The weight of the complete machine equipped for field operation. The weight shall be determined under the conditions specified in cutter bar height no. 16 and the fuel tanks shall be full. If other equipment options or attachments affect the weight, such equipped shall be specified. Combine weight shall be expressed in quintals.
Combine length: The overall dimension from the foremost point to rear-most point of the combine equipped for field operation measured parallel to the longitudinal centre line of a combine. The header installed shall be stated, and if other equipment options or attachments affect the length, such equipment shall be specified. Combine length shall be expressed in whole centimeters.
Combine height: The vertical distance from plane on which the combine is standing to the highest point on the combine. The height shall be measured under the conditions expressed in cutter bar height no. 16. The height with all components in position for field operation shall be specified. Combine height shall be expressed in whole centimeters.
Combine width: The overall width measured horizontally covering outer extremities of combine expressed in millimeters.
Ground clearance: The height of the lowest point of the combine from a level supporting surface when the combine is fitted with all its usual accessories, fuel, radiator, hydraulic, lubrication and grain tank full and tyres inflated to recommended pressure for field work.
Ground contact area (Track): Product of track chain length and width on ground multiplied by two, expressed in square millimeters.
Length of track-chain on ground: Length at base of track shoes disregarding the grouser, as measured between first and last track roller centers, on from front idler wheels centre line if they are so designed as to hold the track chain level with the track rollers expressed in millimeters.
Medium plain of wheels or tracks: It is equidistant from the two planes containing the periphery of the rim or tracks at their outer edges.
Specific ground pressure: The quotient of front axle mass and ground contact area, giving a rating comparable to tyre pressure in case of wheeled combine.
Wheel base: The horizontal distance between front and rear wheels on a wheeled combine measured at the centre of ground contact.
Wheel-base: The horizontal distance between front and rear wheels on a wheeled combine measured at the centre of ground contact.
Wheel track: The distance between the median planes of wheels or tracks on the same axle measured at the point of ground contact.
Width of track-chain on ground: Width of track shoes including rounded ends if any expressed in millimeters.
Discharge height of unloader: The vertical distance from the plane on which the combine is standing to the lowest point of the discharge opening with the unloader in operating position. The height shall be measured under conditions specified in cutter bar height 16; discharge height shall be expressed in whole centimeters.
Clearance height of unloader: The vertical distance from the plane on which the combine is standing to a point on the underside of the unloader located at a horizontal of 914 mm from the lowest point of the discharge opening.
Reach of unloader: The horizontal distance measured perpendicular to the longitudinal centre line of the combine from the lowest point of the unloader discharge opening to the outermost point of the header on the unloader side. The reach shall be measured under conditions specified in discharge height of unloader and expressed in whole centimeters.
Grain tank capacity: The number of the volumetric units of wheat that are unloaded by its own unloading system expressed in cubic meters.
Grain tank unloading time: It is the minimum time in seconds required to unload the grain tank capacity.
Reaper: A machine to cut grain crops.
Side delivery reaper: A machine which harvests crops and delivers them on the side having the space for the next run clear.
Windrower: A machine to cut crops and deliver them in a uniform manner in a row.
Binder: A machine for cutting standing crops and tying them into neat and uniform sheaves.
Cutter loader: A machine to cut crops and to deliver them to vehicle.
Ejection: Throwing of the tied bundles over the conveyor of a reaper binder.
Knotting: The operation of automatic tying of bundles in a reaper binder.

Last modified: Wednesday, 11 September 2013, 9:03 AM