Plough disc blades, 24″ and 26″
Our largest diameters in the full 5 mm gauge, pressed to a deeper concavity, for disc ploughs, one-way ploughs and vertical disc ploughs in black cotton soil and hard land. 26″ is the biggest disc we make.
A plough disc is a different animal
People often ask for “a big harrow disc” when what they need is a plough disc. The two look similar and are not interchangeable. A harrow disc runs in a gang, shallow, sharing the load with its neighbours. A plough disc works alone on its standard, cutting deep and lifting a full furrow slice, and the soil pushes back hard against one face the whole time.
So a plough disc is built heavier in three ways: the largest diameter we make to reach depth, the full 5 mm section to carry the bending load, and a deeper dish so it turns the slice over instead of just slicing it.
Concavity is the part people overlook
Concavity — the depth of the dish — is what decides how aggressively the disc turns soil. Too flat and the furrow slice falls back where it came from. Too deep for the job and the plough pulls heavier than the tractor can comfortably manage, and the disc wears unevenly.
We press concavity in a die while the blank is hot, against a master gauge, and check it again after heat treatment. A disc that has been pressed cold, or pressed and then warped in the quench, will wobble on the hub and wear on one side — which is the usual reason a cheap plough disc fails early.
Sizes we make
| Diameter | mm | Thickness | Concavity | Centre hole |
|---|---|---|---|---|
| 24″ | 610 | 4.5 / 5.0 | 55 mm | 1¼″ sq. |
| 26″ | 660 | 5.0 | 60 mm | 1¼″ · 1½″ sq. |
For stony or black cotton land take 26″ at the full 5 mm. If your plough needs a disc larger than 26″ or thicker than 5 mm, tell us honestly — that is outside what we manufacture.
Typical applications
- Disc ploughs — primary tillage in hard and dry land where a mouldboard will not enter
- One-way ploughs — combined cutting and turning in one pass
- Vertical disc ploughs — deep work in sticky black cotton soil
- Land reclamation and orchard work — breaking root-bound and long-fallow ground
Built for shock, not just for wear
At ploughing depth a disc will meet stones and old roots, and a disc that is only hard will chip or crack. Ours are quenched and then tempered to 42 HRC, which gives up a little surface hardness in exchange for the toughness to survive that impact. Every batch is hardness-tested and gauged for concavity and flatness before it is blasted, painted and stamped with the Hippo® seal.
Send us a drawing, a photo, or simply one worn-out disc by transport. We will match the diameter, thickness, concavity and hole, and send you a sample before you commit to a batch.
Questions we get asked
What is the difference between a plough disc and a harrow disc?
A plough disc is larger, thicker and more deeply dished. It is built to turn a furrow at depth on a disc plough, so it carries far more side load than a harrow disc, which works shallower and in a gang.
Which size plough disc do I need?
It is set by the plough, not by preference - the frame, the bearing hub and the standard are all built around one disc size. Measure the old disc across the face and the square hole across the flats, or send us a photo.
Do you make discs for one-way and vertical disc ploughs?
Yes, in 24″ and 26″ at 5 mm with deeper concavities. Send the drawing or one old disc as a sample and we will match it.
What thickness is right for black cotton soil?
Heavy black cotton and hard, stony land call for our full 5 mm gauge in the largest diameter, because the disc carries shock loads as well as wear. We do not make discs thicker than 5 mm.