2 June 1995

Trials show big potential for HPC conditioner

Greenlands prototype HPC conditioning unit appears to be causing quite a stir among high dry matter silage enthusiasts. Andy Collings went to see whether such interest holds water

"DEVELOPMENT of the Green-land HPC conditioner is one of the most significant advances in the production of high dry matter silage," says Shropshire contractor Richard Furber.

Based at Audlem, Mr Furber is one of a handful of contractors and farmers trialling the unit this year before the start of commercial production due next year.

"We sent two samples of grass for laboratory testing – one which had passed through the HPC conditioner and another which had not. Both were cut at the same time and sampled at the same time later that day," he explains. "The results revealed the conditioned sample had a 32.3% DM and the other 24.5% DM."

Similar results are also reported to have been recorded in independent trials at IGER Aberystwyth.

Avoids tedder pass

Mr Furber adds that the HPC leaves grass spread evenly over the width of the mower avoiding the need – and the cost – for a pass with the tedder. "We leave the grass just as it leaves the conditioner," he says. "The only operation is to row up just in front of the forage harvester, usually within 24 hours of mowing."

All of which must be music to the ears of Greenland UK, which clearly has high expectations for its High Performance Conditioner (HPC).

Still considered to be in its "development" year, the HPC system is, on the face of it, reasonably simple: Cut grass passes through a small gap between two rollers – one having stiff nylon bristles and the other horizontal bars.

Both rollers are powered, with one rotating faster than the other to cause a "rasping" action designed to break down the outer covering of the stems and speed wilting.

A freewheeling third roller having a box section deflects the exiting grass on to the ground. But there is more to the system than this description perhaps suggests.

At a demonstration held on a farm near Nantwich, the HPC was fitted to a PZ CM 300A trailed mower – itself a new development for this season from the Greenland camp.

Cut off one edge

A four-drum mower having a 3m cut, it has a pivot point at the drawbar to enable it to be operated to the left and right of the tractor – the advantage being that a field can be cut off one edge rather than in lands.

Drive to the conditioner is taken from the drum drive and down the right-hand side of the unit. Four Vee-belts convey the drive from the primary pulley around the two roller pulleys – one of them having a reduction box to create the required roller speed differential. Belt tension is maintained by an idler pulley which is also connected to an over-centre device which, in the event of an overload or a blockage, springs the idler pulley away from the belt to slacken the belts and stop the drive. Straightforward so far, but the two driven rollers are also linked to the overcentre device with the result that when tripped, the rollers are parted a few inches to release any trapped grass.

The gap between the two rollers is thought to be a critical factor in ensuring correct conditioning of the crop, although the manufacturer appears to be still working on assessing just what the setting should be.

A lever on the left of the machine is able to increase or reduce the gap in much the same way a combine harvester concave gap is set. For most circumstances the gap is set to one of less than 2mm.

Fine-tuning needed

Impressive as the HPC clearly is – grass exiting the conditioner had a distinctly moist feel to it – there is still a degree of fine-tuning necessary before the machine is launched.

One area which Greenland engineers are working on is to fit variable deflectors for the exiting grass. Current models are only able to deflect the grass to the left, which is not over-satisfactory if the potential of left- and right-hand-cut mowers like the CM 300 A is to be fully exploited.

It is also too early to assess the wear rate of the nylon bristles on the top roller. Technical manager Tim Baker believes that a contractor like Mr Furber, who reckons on cutting 1200ha (3000 acres) of grass each year, could expect to change the nylon roller at the start of each season. In terms of power requirement Mr Baker estimates the HPC to put another 20-30hp on the bill.

HPC versions under test in the UK this year comprise those for attachment to 2.4m mounted disc, 2.6m mounted drum, 2.8m trailed disc and 3m trailed drum mowers. &#42