Operating tips

Get the most out of your rotary tiller and ensure your own safety by follow­ing the following operating tips:

• Do not leave the tractor’s seat while the engine is still running.
• Shut the engine off before lubricating, inspecting, or adjusting the cultivator.
• Do not allow anybody near the tiller while the tractor is running.
• Lift the tiller clear from the surface, engage the PTO-shaft and thereafter lower the tiller to the soil for tillage purposes.
• Raise the tiller before making turns.
• If the engine speed drops while working with the tiller, the PTO speed will also drop, and the tractor must be shifted to the next lower gear to maintain a PTO speed of 540 rpm (or 1 000 rpm).
• Use the slowest rotor speed which provides the desired tilth. This uses the minimum of power input and results in less wear.
• Do not transport the cultivator at a high speed over a rough terrain.
• Do not attempt to block the rotor by hand to test the slip clutch.
• Use a piece of wood and position it securely.
• Use only recommended PTO-shafts.
• Keep the PTO-shields in place.
• Do not work near, or step over the PTO shaft while it is running.
• Use adequate tractor front-end weights for stability when transporting three-point-hitched rotary tillers.
• At least 55% of the static tractor front-end weight must be retained on the front wheels when the cultivator is raised for transport.

 Troubleshooting

Improper operation and adjustments are the usual causes of unsatisfactory rotary tiller performance. If the tiller is not functioning correctly, check the following symptoms and make the necessary corrections:

If the rotor does not turn when it should, it can be due to one of the fol­lowing causes:

• The PTO-shaft or gearbox could have seized or failed.
• The slip clutch could be worn, or out of adjustment.
• The rotor can also be obstructed.

If a rough and uneven operation is experienced, it can be related to a machine that is either too high or too low for the universal joins on the PTOshaft. It can also be that the universal joints are worn out, or that the blades on the rotor are not arranged in the correct scroll pattern.

If excessive noise comes from the cultivator, it can be related to a gear failure in the gearbox or in the drive train. Bearing failure also creates lots of noise. Check the oil level in the gearbox and a possible stone obstruction wedged between two blades.

If the tiller tends to sway to one side, one of the sway blocks on the tractor may be missing or the sway blocks on the tractor are improperly placed. Other possibilities are that the tiller is not working well, or that the tractor’s three-point-linkages, or the depth-wheels on the cultivator, must be adjusted.

If the blades fail to penetrate the soil or do not remain working at the correct depth, the hydraulics on the tractor must be set correctly, or the land speed must be reduced. The blades may also bent or not arranged in the scroll pattern. The rotor speed can also be too low. If severe blade breakages occur, it can be related to loose blade bolts or too many obstruc­tions in the soil, in which case more than one run is recommended with a deeper blade setting during every run.

If the power requirement is very high during the tilling process, the rotor speed may be too high or the blades may be bent, broken, or incorrectly arranged. It can also be that the tiller is set too deep for that specific run, or that the land speed is too high.

If the rotor plugs with soil, it can be that the soil is too wet to be cultivated or that the rotor speed is too slow in relation to the land speed. The blades can also be bent or incorrectly ar­ranged. The rotor will tend to plug when wet soil sticks to the rear shield.

Rotary versus conventional tillage

Interest in rotary tillage has been spurred because of soil compaction and the extreme weight required to develop sufficient traction for large tractors to pull big ploughs and disc harrows.

Compaction is reduced with a rotary tiller because fewer trips are made over the field, and by reducing tractor weight. In some cases, rotary tillage is referred to as minimum tillage because of the limited number of operations re­quired to prepare a seedbed. However, if not used correctly, rotary tillage may be excessive tillage that damages soil structure and results in surface pud­dling and crusting.

In most cases, rotary tillers actually provide a negative draft. That means that the rotating blades tend to push the tractor forward as the soil is culti­vated. The land speed of the tractor is controlled by the engine and therefore the tractor must have a direct-drive gearbox to oppose free-wheeling in the forward direction.

Because the soil is stirred only once or twice in one season, more moisture is retained in the soil than with conven­tional tillage, and potential purchas­ers of rotary tillers must consider all advantages of their use compared to conventional ploughing, disking, har­rowing and other types of cultivation.

Rotary tillers are versatile and use­ful implements, but their principles of operation are unique, and must be understood for satisfactory results. They are heavy consumers of energy, and may use as much energy per cubic metre of soil moved as all three operations of ploughing, disking, and harrowing. Time and manpower sav­ing is possible, implement investment may be less than for traditional tillage methods, tractor-wheel soil compaction is reduced and less soil moisture is lost by one operation than would be by three.

Each farmer should determine for himself whether he should include rotary tillage in his soil management, and a discussion with a nearby farmer who already has adopted rotary till­age would be an excellent first step towards such an important decision.

We thank the ARC Agricultural Engineering in South Africa who made the information on rotary tillers available to the readers of ProAgri Zambia.