14 April 1995

Coppice harvesters are put to test by Forestry Authority

By Andrew Faulkner

FOUR short rotation coppice harvesters are being evaluated by the Forestry Authority as part of an ongoing trial to assess coppicing machinery.

The trial is part of a three-year project, jointly funded by the Forestry Authoritys Technical Development Branch (TDB) and the Energy Technology Support Unit (ETSU). It aims to find out which types of harvester are most suited to UK conditions – the harvesters were initially developed to work in Scandinavia.

TDBs Richard Deboys explains: "There are two main differences between harvesting conditions in Scandinavia and the UK. Here we harvest between November and March in wet ground conditions, whereas in Scandinavia the surface is frozen. They grow only willow, while we also plant poplar."

The TDB is currently testing four machines: A Claas self-propelled "cut and chip" harvester, a Salix Maskiner tractor-mounted "cut and chip" harvester, a John Deere self-propelled forager and a Segerslatt Empire 2000 self-propelled stick harvester. All four machines work differently.

Based around a conventional self-propelled forager, the Claas machine uses a modified twin-row sugar cane header for harvesting short rotation willow and poplar coppice.

Stems are funnelled by a V-shape bar into the header, cut by a pair of saw blades and fed into the drum chipper. The 30mm (1in) chips are then blown into a ferrying trailer.

Salix Maskiners Bender harvester, as its name suggests, bends the coppice stems in two before chipping. Designed to fit on a reverse-drive tractor, the harvester uses transport chains to feed the bent stems into a chipping mechanism. Again, the Salix machine produces chips of about 30mm in length.

Probably the machine most closely related to its farming equivalent is the outfit from John Deere. Only minor modifications are made to the forager/Kemper header to make it suitable for coppice harvesting.

Gathered by dividers

Stems are gathered by dividers, clamped between specially shaped points on the feed drum, and cut. The cut stems are then directed through the chipper before being blown into the ferrying trailer.

The final machine on test, the Segerslatt Empire 2000 stick harvester, is still in prototype form. Based on a Case IH combine harvester, the machines front augers gather the coppice stems for cutting by twin discs. Transport belts then transfer the stems to a collection chamber, ready for dropping off at the end of the row.

Because the project is still mid-term, the TDB says final conclusions have yet to be drawn.

According to Mr Deboys, initial impressions are that all the harvesters are capable of successful operation in the UK.

"All show useful potential, but still need further minor modification to cope with the thicker, more brittle poplar stems and what are often very wet ground conditions."

Included in the final stage of the TDBs trial will be work on the effects of ground damage at harvest on coppice regrowth.

Segerslatts Empire 2000 differs from the other three machines on test; its a "stick", not a "chip" harvester. Cut sticks are dropped on headland.

Above: The Claas forager uses a modified sugar cane header to harvest short rotation coppice. Below: This Kemper header/John Deere forager combination has only undergone minor modification from its forage maize mode. Both Claas and Deere machines blow chips into trailers.