Accidents caused by agricultural machinery are widespread but rarely talked about. The accidents usually result in serious injuries, amputations and, in some cases, death.

Livestock farmers are most affected, sometimes losing limbs as they feed into the chute of chaff cutters.

In response, Egerton University has developed a pneumatic chaff cutter and improved the existing model to reduce this menace.

Dr Joseph Alele, from the Department of Agricultural Engineering at Egerton University, explains to MtaaWangu how the pneumatic and improved chaff cutters work and their key safety principle.

Dr Joseph Alele, from the Department of Agricultural Engineering at Egerton University.

Photo credit: Leleti Jassor/Mtaa Wangu

"The pneumatic chaff cutter works by sucking in the material with a powerful stream of air created by an inverted fan. As the material enters the hopper, the air suction takes over from gravity and pulls the material towards hidden knives that cut it into smaller pieces," explains Dr Alele.

The standard of hidden knives, he says, is a guideline set so that the knives cannot be reached by hand, to avoid any chance of accidents.

"The new technology was prompted by the number of injuries people were suffering when preparing fodder, particularly when using chaff cutters. People were losing fingers, especially when using the panga, hand-rotated and electric chaff cutters," he notes.

The machine also has a discharge chute with a screen. The sieve comes in different sizes, depending on the fineness of the material you want. If you want very fine material, you'll have a sieve with smaller sieves, and if you want larger material, you'll increase the size of the sieve opening as you go along.

The traditional chaff cutters.

Photo credit: Leleti Jassor/Mtaa Wangu

Using the same air principle, the machine can still blow material 10 metres away from it. For organised trough setups, you can use a board to block the first trough, fill it, then remove the board and extend the feed into the next trough until finished.

"The machine can chop both dry stalks and fresh vegetables, such as sukuma wiki and cabbage, and shred them into very fine materials. It can chop up to half a tonne in an hour and you can get 4 tonnes in 8 hours, which is impossible to do by hand."

The machine is made from locally sourced materials and costs Sh65,000.

"When we introduced the pneumatic chaff cutters as a safety-enhancing machine, many farmers asked what they could do with the existing normal cutters they had. We then went back to the drawing board to see how we could improve the safety of the cutters," says Dr Alele.

Normally, when the normal chaff cutter grabs the material, there's no way of stopping it from pushing the material in unless you switch it off. The switch is hidden and the cable almost always goes to the kitchen or a power source far away.

"Safety is paramount with this machine. The exposed knives in traditional chaff cutters have caused people to lose fingers and even hands. With our invention, we've addressed this by moving the switch closer for easy on/off operation and encasing the knives, significantly reducing the risk of injury."

The improved chaff cutter with it's casing.

Photo credit: Leleti Jassor/Mtaa Wangu

The improved chaff cutter costs Sh95,000 and can chop one tonne of fodder in an hour for a machine with two knives. Output and fineness can be increased by adjusting the number of knives to suit the farmer's requirements.

In addition, its main advantage is that it does not spill the material. It gathers all the chopped material in one place, allowing direct bagging during operation.

New chaff cutter technology hopes to reduce farm accidents

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Leleti Jassor