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De-stoner comparisons<br />

Do you search the web or reach for the<br />

stars? Confused? We hope not, but<br />

putting de-stoning into perspective<br />

should help:-<br />

25 years of de-stoning experience is<br />

reflected in the types of machines that<br />

<strong>Grimme</strong> offers in today’s demanding<br />

market place. With ever closer examination of<br />

all costs, this very important operation for the<br />

majority of <strong>UK</strong> growers has to be done<br />

correctly, whether it is the need to remove stones<br />

or clod or both from the prepared bed.<br />

Machine<br />

Types<br />

<strong>Grimme</strong> offers<br />

three separator<br />

systems within<br />

the de-stoner<br />

chassis to give<br />

the grower a<br />

solution that is<br />

tailored to<br />

individual needs.<br />

1: Star and Web 3: All Web<br />

This layout consists of share, intake<br />

roller and 7 rows of stars followed by a<br />

web. The star spacing has to suit the<br />

requirement and so does the web. The<br />

star system also offers the optional<br />

facility to increase separation by<br />

altering the relative height of 3<br />

alternate star shafts within the bank of<br />

7. This feature is extremely useful where<br />

the machine works in varying soil types.<br />

This layout is preferred where declodding<br />

is the norm. The more stars in<br />

a machine, the more separation can be<br />

achieved. However, <strong>Grimme</strong> recognises<br />

that the star section needs to be kept<br />

full to prevent unwanted material being<br />

extracted into the bed. As a result, 7<br />

rows of stars and a web combine to<br />

prevent this and to enable the machine<br />

to work more efficiently where some<br />

stone is present.<br />

2: Star - Web - Web<br />

This layout consists of share, intake<br />

roller, 3 rows of stars and then two<br />

webs. Both the star spacing and the<br />

web spacing must be configured to suit<br />

the individual grower’s requirement.<br />

Fitted with or without spacers the star<br />

pitch matches the web pitches. In<br />

principle, the rear 2 webs operate in<br />

the same way as the rear webs of the<br />

All Web machine.<br />

This system has a stronger share<br />

assembly, well suited to stony<br />

conditions and with the intake roller<br />

improves the feed into the machine,<br />

especially on downhill work.<br />

Note Web – Star – Web: The<br />

positioning of stars behind a web within<br />

the machine was found to slow soilflow<br />

through the machine and created<br />

the further problem of marrying the<br />

web/star/web combination to prevent<br />

material loss – Note: <strong>Grimme</strong> rejected<br />

this system at the development<br />

stage.<br />

This layout consists of a share followed<br />

by 3 webs. The web pitches (sizes)<br />

remain the same or reduce in pitch<br />

through the machine. The progression<br />

of the sieving requires smaller pitches<br />

that keep in unwanted material, which<br />

is then buried in the trench.<br />

The All Web system suits land with<br />

abrasive stone content, or where star<br />

type systems are not accepted or<br />

required. In the early days of de-stoning<br />

all machines were produced in this<br />

format.<br />

The need for clod removal rather than<br />

stone removal was responsible for the<br />

introduction the newer concept of star<br />

systems, all based on <strong>Grimme</strong>’s original<br />

harvester star separation systems.<br />

The Future – What<br />

does it hold?<br />

Multi-bed de-stoning systems do not<br />

provide the advantages seen with<br />

bed openers and multi row<br />

planters.<br />

The three bed system has been tried<br />

but it is now accepted that using a<br />

machine in varying soil types and<br />

trying to dispose of varying amounts<br />

of stone/clod is impracticable as a<br />

reduced cost system.<br />

The one man - one machine scenario<br />

glosses-over the practicalities. Similar<br />

difficulties exist with a two-bed<br />

system as does the fitment of a<br />

power unit to match the wheelings.<br />

Given these constraints we must<br />

continue to develop the existing<br />

single bed system.<br />

With technological advances in<br />

design, construction and material<br />

development we look forward to a<br />

future of stars, webs and<br />

combinations of the two.<br />

Still confused? – watch this space!<br />

DE-STONER APPRAISALS DE-STONER COMPARISONS 1: STAR & WEB 2: STAR - WEB - WEB 3: ALL WEB

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