Types of disc plough

(i) Standard disc plough:

• It consists of steel disc of 60 to 90 cm diameter, set at a certain angle to the direction of travel.
• Each disc revolves on a stub axle in a thrust bearing, carried at the lower end of a strong stand which is bolted to the plough beam.
• The angle of the disc to the vertical and to the furrow wall is adjustable.
• There is little inversion of furrow slice as well as little burying of weeds and trashes.

Some terminologies

a) Disc – It is a circular, concave revolving steel plate used for cutting and inverting the soil.

b) Disc angle – It is the angle at which the plane of the cutting edge of the disc is inclined to the direction of travel. Usually, the disc angle of good plough varies between 42° to 45°.

c) Tilt angle – It is the angle at which the plane of the cutting edge of the disc is inclined to a vertical line. The tilt angle varies from 15° to 25° for a good plough.

d) Scraper – It is a device to remove soil that tend to stick to the working surface of a disc.

e) Concavity – It is the depth measured at the center of the disc by placing its concave side on a flat surface.

f) Centre of power- It is the true point of hitch of a tractor.

g) Centre of resistance- It is the point at which the resultant of all the horizontal and vertical forces act. The centre lies at a distance equal to 3/4th size of the plough from the share wing.

h) Line of pull- It is an imaginary straight line passing from the centre of resistance through the clevis to the centre of pull (power).

i) Pull- It is the total force required to pull an implement.

j) Draft- It is the horizontal component of the pull, parallel to the line of motion.

Draft depends upon 1) sharpness of cutting edge 2) working speed 3) working width 4) working depth 5) type of implement 6) soil condition and 7) attachments.

k) Side draft- It is the horizontal component of the pull perpendicular to the direction of motion. This is developed if the center of resistance is not directly behind the center of pull.

l) Unit draft- It is the draft per unit cross sectional area of the furrow.

m) Theoretical field capacity- It is the rate of field coverage of the implement, based on 100 per cent of time at the rated speed and covering 100 per cent of its rated width.

n) Effective field capacity- It is the actual area covered by the implement based on its total time consumed and its width.

o) Field efficiency- It is the ratio of effective field capacity and theoretical field capacity expressed in percent.

p) Soil pulverization- It is the quality of work in terms of soil aggregates and clod size. This is measured by cone penetrometer.

ii)Vertical Disc Plough:

• It is the plough which combines the principle of regular disc plough and disc harrow and is used for shallow working in the soil.