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Valmet H800 | Picture made by valtradriver
Photo of a Valmet H800, busy posing. Sometimes you come across special things at the W.W.W. like this Valmet: Valmet's continuously variable H800 The continuously variable VPS transmission is not the first of its kind in the history of Valtra. As early as 1966, the Valmet 565 was presented with a hydrostatic creep gear, which was later the mid-1970s was introduced on the Valmet 702 and 702S models. Creep gears were especially useful in the peat bogs. The first model with a fully hydrostatic transmission was the Valmet H800. In the mid-1980s, the Tractors Group Valmet appointed a special project team to develop a tractor concept purchased from an external tractor concept purchased from an external series production. This was an extremely interesting tractor. It was split down the middle and all four wheels were the same size. The cab was on the front half along with the engine. The remarkable thing was that the steering wheel, the pedals and the seat formed a platform that could could rotate 180 degrees within the cabin. This allowed the tractor to be driven in both directions just as easily controlled. The loader was then also mounted on the rear half so that the tractor could be used as a bulldozer, since the chassis was articulated and the driver had excellent visibility of the loader. The H800 was powered by a Valmet 411 DS Turbocharger four-cylinder 4.4-liter engine that produced 110 horsepower (DIN). The transmission was fully hydrostatic. At that time, suppliers of hydraulic components began to supply rotary motors that were mounted on the wheel hub. The capacity of the motors was also variable. At low travel speeds a large capacity was used for each revolution of the wheel, while at higher speeds the capacity was reduced so that the oil flow rate was reduced. There were three hydraulically selectable gear groups, and shifting between forward and reverse was occurred by reversing the direction of flow. Of course, the speed was infinitely adjustable. The H800 had separate pumps for the front axle and the rear axle. There were no mechanical transmission parts between the engine and the wheels. The revolutionary nature of this tractor was further enhanced by the fact that it was equipped was equipped with a load-sensing hydraulic system whose variable piston pump had a capacity had a capacity of 140 l/min. Four external hydraulic valves were standard. The Valmet H800 was unveiled as a concept tractor at the SIMA exhibition in Paris in 1987 where it received considerable attention. Subsequently it was further developed to reach series production production. Since most of the design work had been done by an outside project team, the the construction did not match the in-house methods of the factory, which caused problems. When all over the world the tractor industry was hit by the depression in the early of the 1990s, Valmet was forced to discontinue the H800 program to be discontinued. Nevertheless, a single H800 has been working in the field for the past twenty years in practice at the site of the Suolahti plant - proof that the concept does indeed work. Hannu Niskanen
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