Categories: Articles, TillingPublished On: 19th July 2021

Rotary tillers are simple but effective: Part 1

By 5 min read

The self-propelled, walk-behind garden model

This month we start a new series on a very popular implement. A rotary tiller should be regarded as an alternative soil cultivation implement that can function in cooperation with other implements, for example tine implements. Some of the rotary tillers are self-propelled and some are tractor driven.

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

Some people refer to rotary tillage as minimum tillage because of the limited number of operations required to prepare a seedbed. But, if not properly used, rotary tillage may actually be excessive tillage that damages soil structure and results in surface puddling and crusting.

Four types of horizontal-axis rotary tillers are available for agricultural applications, namely:

  • The tractor drawn, or mounted model, powered by the PTO-shaft of the tractor
  • The tractor drawn, or mounted model, with an auxiliary engine for the cultivator
  • The self-propelled four-wheel model

The self-propelled, walk-behind garden model

This type of rotary tiller can do thorough, spade-deep hoeing in heavy soil (see Figures 1, 2 and 3).

Figure 1: The walk-behind garden model.

Figure 2: The small garden model is easy to handle.

Figure 3: The heavy-duty blades on the rotor can cut spade-deep into heavy soils.

This type of rotary tiller is compact and light weight and is also very manoeuvrable. In some cases, the handlebar can be turned 180° to allow the operator to work in both directions. The handlebar can also be stepwise adjustable in height and width. The handlebar can be adjusted to allow the operator to walk beside the cultivator (see Figures 4 and 5).

Figure 4: A small two-wheel tractor can be equipped with a rotary tiller and consists of the following:

1) The rotor with its protective shield

2) The implement coupling device

3) The handlebar which can swivel 180° and is adjustable in height

4) A four-stroke petrol engine

5) The gear lever that can be switched from forward to reverse

6) Adjustable track width of the wheels for different tasks

Figure 5: The handlebar can be turned sideways to allow the operator to walk next to the machine and not in the loose tilled soil.

Typical working widths are 10 to 100 cm and gears can be switched from forward to reverse. A safety device prevents the rotor from rotating when the machine is reversed and the engine stops immediately when the handlebar is released.

The rotor is normally equipped with a support wheel to ensure sufficient ground clearance to prevent damage to the blades during the transport process (see Figure 6).

Figure 6: The support wheel is used to prevent the rotor from being damaged during transport.

The required tilling depth can be adjusted between 2 and 20 cm and some of the machines have up to three different land speeds.

The rotor is independent of the land speed which makes it possible to reach an optimum tillage, even in soil with a high moisture content.

Small rotary tillers can be equipped with one or two drive wheels. The one-wheel rotary cultivator makes it easy to till between narrow rows for instance (see Figure 7).

Figure 7: The one-wheel rotary tiller makes it easy to till between narrow rows.

In some cases, the small rotary tillers consist only of an engine and a rotor with blades for cultivating purposes. No land wheels exist and the rotating action of the blades moves the machine forward. The power is transferred from the engine, through a gearbox and differential to the rotor (see Figure 8). The working depth of the rotor is controlled by adjustable skids at the bottom of the frame (see Figure 9).

Figure 8: The rotor and blades on a small garden model without a drive wheel.

Figure 9: The bottom of the cover also serves as skids to control the working depth of the blades.

Some of the small two-wheel tractors can be equipped with rotary tillers. Some are equipped with up to 10 kW engines, with five forward and two reverse gears as well as a PTO-driveshaft. The rotary tiller is then driven by the tractor’s PTO-shaft and can be especially useful as garden tillers. They can also be used by a small-scale farmer that wants to cultivate a field up to one hectare in size (see Figure 10). These tillers are not only intended to loosen the soil, but to control weeds as well.

Figure 10: The movement of the rotor blades loosens the soil and can also destroy weeds.

The rotary tiller produces a fine tilt because the clods, loosened by the blades, are whirled up to the top cover and are broken into smaller pieces by the impact, before they fall back onto the rotor and are chopped again. This process loosens and aerates the soil while preparing it for sowing or planting (see Figure 11).

Figure 11: The clods are whirled up to the protective shield (top cover) and broken into smaller pieces by the impact before being chopped again.

Note that the operator can work in forward or reverse gear with the tractor. This can be done by swivelling the handlebar 180° and by turning the rotor the other way around (see Figure 12).

Figure 12: The handlebar can be turned 180° to allow the operator to operate the tractor in reverse gear.

Next month we shall look at the tractor-drawn model. We thank the ARC Agricultural Engineering in South Africa who made the information on rotary tillers available to the readers of ProAgri Zambia.

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