Disc Harrow Guide | Single & Double Action Disc Harrow, Structure, Adjustment & Uses for Tractor

A disc harrow is a widely used secondary tillage machine, applied after primary ploughing (reversible plough work). Unlike primary tillage ploughs that deeply turn over soil, disc harrows work on shallow topsoil without massive soil shifting, consuming less fuel per acre. It is a must-have tillage tool for family farms, agricultural cooperatives and large commercial farms in Mexico and South America.

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Secondary tillage aims to create loose, uniform seedbeds for sowing. Rotating concave disc blades cut, crush clods, uproot weeds, chop crop residues and mix organic straw into topsoil, solving soil compaction, stubble accumulation and weed overgrowth problems.

Disc harrows for tractors are classified by soil turning direction into two mainstream models, matching different field conditions:

Single Action Disc Harrow Two opposite gangs throw soil outward separately (right gang to right, left gang to left). Suitable for light clod breaking, small plots and sloped terraces, compatible with low-horsepower tractors.

Double Action Disc Harrow Front and rear gangs turn soil in opposite directions, completing double tillage in one pass. Working width ranges from 1.5m to 4.6m (5–15ft). It is the top-selling heavy-duty disc harrow for hard ground, heavy straw residue land and wasteland reclamation, highly popular among large-scale Mexico farms for superior straw cutting effect.

By traction type, disc harrows are divided into tractor drawn disc harrow and animal drawn disc harrow; global commercial farms all adopt tractor drawn models for high efficiency.

1.Disc Blades

Concave hardened steel plates, diameter 35–70cm for tractor harrows. Two mainstream styles:

Plain disc: smooth edge for regular clod crushing & leveling

Cutaway disc (notched disc): serrated edge for cutting tough straw, weeds and old roots, best for straw return farming Disc concavity directly decides penetration depth and soil pulverization effect.

2.Harrow Gang

A set of discs installed on one arbor shaft. Spacing between discs: 15–25cm for light harrows, 25–30cm for heavy-duty disc harrows. The angle between gang shaft and tractor forward direction is gang angle, the core structure to adjust tillage depth.

3.Gang Bolt / Arbor Bolt

Heavy-duty long bolt with square head to fix the whole disc gang, impact-resistant for long-hour continuous field work.

4.Spools & Spacers

Flanged sleeves between every two discs, standard spacing 17.8cm (7 inches), prevent disc shifting and ensure uniform tillage.

5.Bearings

Heavy cast iron bearings bear radial and axial thrust from soil pressure, low failure rate and long service life.

6.Transport Wheels

Equipped on drawn disc harrows to lift blades during road transportation and avoid blade abrasion; mounted disc harrows require no transport wheels.

73Scrapers

Stick closely to concave disc surfaces to remove sticky mud and prevent blockage during continuous operation.

8.Weight Box

Add extra counterweights to increase downward pressure, boost disc penetration depth for hard compacted soil.

Many farmers struggle with shallow penetration and poor pulverization, adjust the machine by the following methods to fit dry land, stubble land and wasteland:

1.Enlarge the gang angle of disc blades

2.Add counterweights in the weight box to increase downward pressure

3.Lower the tractor hitch point

4.Replace sharp small-diameter low-concavity cutaway disc blades

5.Operate at recommended constant working speed for optimal clod crushing result