30 October 1998

High-tech to fore in Valmet range

Three new tractors, a

computer controlled

transmission and front

suspension – Valtra keeps

pace with modern technology.

Andy Collings reports

TRACTOR sophistication continues – it seems every manufacturer now has a mandate to offer an ever higher degree of technology to its tractor line up.

Finnish tractor manufacturer Valtra is no exception having announced a new computer controlled transmission – HiTech – and a front suspension system which employs air, rather than oil. This announcement coincides with news that three new tractors – the Mezzo 6550, 6650 and 6850 (100hp, 110hp and 120hp) – now join the Valtra range.

But first a look at the transmission. Designated the HiTech system, it has as its centrepiece, a dashboard mounted lever used to control the direction of the tractor – forward or reverse – without having to use the clutch pedal.

This lever has four positions – forward, reverse, neutral and park. In operation, when a change of direction is required, the lever is moved from say, forward position into reverse. Violent directional changes are avoided firstly by the system automatically slowing the tractor to 6.2mph before changes are activated and, secondly, by a smooth take up of power when the directional change has been made. A secondary function allows the reverse and forward speed to be set at different rates so, for example, headland turns requiring a reverse shunt can be made safely without any change of engine speed.

Pulling the collar of the lever while pushing it into its neutral position engages the parking brake. When the engine is turned off the parking brake is automatically engaged – irrespective of the levers position.

Further sophistication is to be found in Valtras 12-speed, Delta powershift transmission which offers three modes of operation.

In position one, the driver is in command of his gear selection – both in terms of the actual gear and the power shift ratio – but still receives advice from the computer regarding a suggested ratio change to optimise efficiency and work output. Position two – "field position" – is designed to maintain optimum engine speed with the computer automatically selecting the most suitable powershift ratio for the job in hand.

The third position is designed for on-road use and instructs the transmission to act as a true automatic transmission, changing up or down according to load. Valtra also maintains that this mode changes down ratios within the powershift ratios to create engine braking when the throttle is closed. Operation of the HiTech transmission does raise the question whether the future of the clutch pedal is secure. Gear selection is achieved using the push buttons on the gear levers. The clutch button is pushed as the gear lever is moved to a new position, sending a signal to the computer which activates the clutch. The result, says Valtra, is a smooth shift through the gear range with the clutch retained only for engine starting, safety and emergencies.

HiTech is available on the new Mezzo models and the Mega range although it is understood that Mega models will still be available with standard transmissions.

Valtra Mega tractors with 6-cylinder engines are now also available with front suspension. A new system which employs air – the Aires system – Valtra claims that it is immune to temperature changes which, in extremes of hot or cold, can affect the operation of hydraulic systems.

The front axle is fitted to a subframe which pivots on bearings at one end and has air suspension and shock absorbers at the other. It is, in effect, the same technology employed by heavy lorries and, by virtue of the fact that an onboard compressor is required, means that there is an air supply which can be used to power trailer brakes.

While Valtra intends to have a few models in the UK early next year, purchasers will have to wait until the summer before they come on stream in volume. Prices are due to be announced at the Smithfield show. &#42