Farm Power & Machinery

Types of Disc Plough

Disc ploughs are of two types’ viz., Standard disc plough and Vertical disc plough.
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 Fig.13.1.
• The angle of the disc to the vertical and to the furrow wall is adjustable. In action, the disc cuts the soil, breaks it and pushes it sideways.
  
• There is a little inversion of furrow slice as well as little burying of weeds and trashes.
  
• The disc plough may be mounted type or trailed type. In mounted disc plough, the side thrust is taken by the wheels of the tractor.
  
• Sometimes a rear wheel is fitted to take side thrust of the plough to some extent.
  
• In trailed type, side thrust is taken by the furrow wheel of the plough. Disc is made of heat treated steel of 5 mm to 10 mm thickness.
  
• The edge of the disc is well sharpened to cut the soil. The amount of concavity varies with the diameter of the disc.
  
• The approximate values being 8 cm for 60 cm diameter disc and 16 cm for 95 cm diameter.
  
• A few important terms connected with disc plough is explained below.


Fig. 13.1 Standard disc plough

Parts of the Disc plough

Disc - It is a circular, concave revolving steel plate used for cutting and inverting the soil.
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°.
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. The disc and tilt angles of disc plough are shown in Fig. 13.2.
Scraper – It is a device to remove soil that tends to stick to the working surface of a disc.
Concavity - It is the depth measured at the centre of the disc by placing its concave side on a flat surface.



Fig. 13.2 Angles of disc plough

Draft of disc plough
The disc plough is lighter in draft than the mould board plough, turning same volume of soil in similar conditions. In very hard soil, some extra weight is added to the wheel which increases the draft. The bearings and scrapers of the disc plough also affect the draft.