How to Handle Disc Coulters That Stop or Turn Slowly on Reversible Ploughs

Disc coulters cut a clean slit ahead of each plough body, slicing residue and opening the furrow wall. When a coulter stops rotating or turns slowly, it drags instead of cuts, and the plough's front edge stops doing its job. Coulter problems are usually simple bearing and pivot issues, but they need attention before the disc itself wears into a groove.

Why coulters stop turning

The most common cause is a bearing that has lost its seal and taken on mud. Once grit enters, the bearing seizes and the disc stops. Bent arms, loose pivot bolts and packed residue around the disc also stop free rotation. A disc that has run seized for a while shows a flat worn spot on its edge, which is a sign the bearing failed some time ago.

Start with grease and cleaning

Most coulters have a grease nipple on the bearing housing. Grease until fresh grease appears at the seals, and clean residue from around the disc. Try turning the disc by hand with the tractor off: a freely spinning disc means the bearing is still alive, and regular greasing keeps it that way. A disc that grinds or will not turn by hand needs further work.

Inspect the bearing and arm

Remove the disc and inspect the bearing for play, rust and rough spots. A bearing that feels gritty when turned slowly is replaced, not repacked with grease. Check the coulter arm for bends and the pivot bracket for cracks. A bent arm holds the disc at the wrong angle, which makes it cut sideways and wear on one edge even when the bearing turns freely.

Set the disc position correctly

After servicing, set the coulter to run directly ahead of the share, just ahead of the furrow wall. A disc set too far out or too far in cuts the wrong line, and the plough body follows an uneven slit. Adjust the arm so the disc sits at the correct depth, just touching the soil, without pressing hard against the ground.

Build coulter checks into the season

At the start of spring and after every stony run, spin each coulter by hand. A free-spinning disc cuts cleanly; a seized one needs attention that day. Keep a couple of spare coulter bearings on the shelf, since they are the part that fails fastest on the front of the plough. Smooth-turning coulters keep the furrow edge clean and the whole plough working at its best.

References

BROWN R T, DAVIES M K. Coulter bearing failure in reversible ploughs[J]. Biosystems Engineering, 2021, 203: 120-128.

Brown, R. T., and M. K. Davies. "Coulter Bearing Failure in Reversible Ploughs." Biosystems Engineering, vol. 203, 2021, pp. 120-128.

Brown, R. T., & Davies, M. K. (2021). Coulter bearing failure in reversible ploughs. Biosystems Engineering, 203, 120-128.