23 August 2002

Giant step for onions is claim for windrower

Machinery to harvest

root crops continues

to become more

sophisticated and

more expensive. Our

Root Harvesting

Special takes a look

at the latest

developments for the

harvest of several

crop types.

Andy Collings starts

proceedings with a

look at a new onion

windrower

Derek Scott: "The point to remember is that the less soil lifted with the onions, the smaller separation area required and the result is a lighter machine overall."

IT IS the most significant development in onion harvesting during the past 15 years, claims Derek Scott for his companys new onion windrower.

Heading up Boston-based Scotts Potato Machinery, Mr Scott has been involved in the development of machinery for harvesting and planting potato crops, since he started his company eight years ago. But now he has decided to apply his expertise to the design and construction of machinery for other crop types.

"I have often thought that existing onion windrowers could be improved," he says. "In the main, they tend to be too heavy, poorly constructed and do little to help the following harvesting operation."

Like several other windrowers Mr Scotts primary cutting and lifting unit comprises a rotating steel rod having a 40mm square section which runs the width of the machine.

But unlike other machines the Scott development has a bar with a 90í twist in it.

"This overcomes the vibration problems which usually occur when an rotating, untwisted square section bar first presents a flat face to the ground and then an angle, and so on," he says. "You have to remember that the ground beneath onions at harvesting time can be rock hard and the constant flat face, angle presentation of the bar as it rotates can cause so much vibration.

Once cut and lifted the onions are assisted on to the first web by a rubber paddle. A gentle agitation occurs at this point before the crop passes on to the primary cleaning web, where a hydraulically driven variable speed agitator wheel helps to shake free any remaining soil.

Onions are then funnelled off the machine into a neat windrow on soil which has been firmed by a roller running beneath the second web.

"The point to make here," says Mr Scott, "Is that the less soil lifted with the onions, the less amount of separation area required. That is why our machine is relatively short in length and light enough for it to be tractor mounted."

Weight saving has also been achieved by constructing the windrower as a monocoque rather than from a chassis.

Mr Scott is keen to point out that, despite achieving a lightweight build, strength has not been compromised.

"It is all about using the correct design technique," he says.

Other notable features on the windrower include spring-loaded side discs which can be pre-loaded to a set degree so that different soil conditions can be catered for.

Machines without this spring loading system frequently end up with bent discs and broken brackets, says Mr Scott.

Similarly, at the rear of the machine where the onions are funnelled into a row, the deflectors also have the ability to lift in respect of changing terrain.

Mr Scott has built only one machine so far and intends to use it this season to iron out any problems.

"The only real fault we need to address is the build-up of trash in the gap between the discs and the body of the machine. Other than that, I feel we have got things about right with clean lifting and gentle handling."

The single-bed windrower will cost about £9000. Versions, which can handle beds with widths from 72-80in and 60-72in, will be available. &#42

Vibration-free onion windrowing …currently a prototype, there are plans to build a three-bed tractor mounted version next year.

Derek Scott has also developed this six-row potato ridge press, which is used after the potatoes have been desiccated to prevent green potatoes forming when the soil is cracked. Refurbished Diablo rollers are used to help keep costs down. Each roller unit has its own adjustable spring loading.