On the Dot... - May 2008
There’s plenty of room in the new Valmet harvester cab. Valmet addresses some crucial areas in its product range.

In the middle of last month, Valmet invited the international forestry press to a snowy Umeå, in northern Sweden, to view the latest additions to their range. The launch raises the machines’ ‘dot’ level, with two harvesters and two forwarders reaching .4 status. The most important changes centre around an enlarged cab, a ‘Comfort’ bogie and a new control system for the harvesters.

The Valmet 901.4 and 911.4 harvesters are fitted with the new cab, which is far more spacious than before. Cab length is 18% greater at 6 feet (184 cm), while the width is increased by 6%. There is also 6¾” (17 cm) more headroom in front of the driver’s seat which, according to Valmet, is more than any other harvester cab on the market. The cab is large enough to carry an instructor without a problem.

Other changes to the cab include a larger air intake and an extra prefilter on the air conditioning. Also, the driver’s seat can be rotated 180 degrees. The 911.4 harvester and the new 840.4 and 860.4 forwarders are all equipped with the Valmet ‘Comfort Bogie’. The new design, which is to be found only on Valmet machines, is an improved version of a well known concept which places more weight on the front wheels of the bogie, and less on the rear wheels. The new design will, according to Valmet, be less prone to burrowing into soft ground, and the fact that the stresses generated are lower should increase the life expectancy of the bogie. Designed by Valmet and manufactured by NAF, the hardening of the surfaces and the meshing of the gears have been modified which again should increase service life – though of course the only way of proving this is to find out over a number of years.The steel in the gears can be either too hard or too soft, apparently, but Valmet are confident that they have the formula spot on. In practice the bogie provides more even ground pressure, which offers a number of positive handling characteristics such as increased climbing ability and greater stability.

Manoeuvrability is improved. The high wheel arch and large bogie suspension have been retained. Another area in which the bogie will make life easier for the contractor is in its maintenance: it needs greasing only every six months, and this can be performed from above. The company noticed that on the old bogies the lower nipples were often ignored by operators, possibly because they could only be reached from underneath, which frequently involved crawling around in the mud. Also, the clearance between the wheels on the Comfort Bogie has been increased by 20mm to enable chains to be attached to both front and back wheels if desired.

Other points that have been addressed on the 901.4 and the 911.4 are that they have a new 115cc hydrostatic pump and 166cc motor. The 901.4 shows an increase in speed over the .3, while the 911.4 has a new gearbox. Pulling force increases from 133 to 162kN. Despite a 4% increase in power, fuel consumption has actually been reduced on the 911.4, while pressure has risen from 250 to 280 bar. Other modifications to the forwarders include the introduction of hydraulic height-adjustable pins on the Valmet LoadFlex option. The pins can also be lowered further than manually adjustable supports, which facilitates transport on a trailer. The supports are activated via buttons in the cab, and each side is controlled separately. Both the Valmet 840.4 and the Valmet 860.4 are equipped with a new PC with a remote screen display for better cab ergonomics.

The forwarders also have a new software suite for the integrated MaxiForwarder control system, MaxiForwarder 4.7, and new features include grapple selection and a hydrostatic motor monitor. The Valmet 860.4 now has greater traction force, and its CRF 11 loader’s lifting capacity has increased by 10% to 126kNm. As we all know from experience, nothing changes faster than computer systems. Valmet’s MaxiHarvester system had been in use since 1998.

Now Valmet has decided to cease updating it, and instead to rewrite the entire system from scratch. The new control and information system, MaxiXplorer, has an interface based on Windows XP. The new PCX computer has 40% more processor capacity than its predecessor, and four times as much RAM – 1 gigabyte. It comes with USB ports and a 12-inch flat screen display. As for the software, the system holds production figures in a database, and the operator never has to leave this environment. There is no need for cumbersome file handling
– the database software does all this for you. The system has a bucking module, MaxiB, which makes it easy to prioritise particular assortments of logs without reference to a price list. Simply select the assortment with the mouse, eg 3.7-metre logs with a maximum diameter of 600mm and a minimum diameter of 160mm, and move it up or down the list by clicking the arrow keys.

The system uses the MHC crane control module that has already been used on the 941. This enables the operator to make the crane behave as if it is of parallel design. As a further refinement, the movement of the head can easily be modified to follow the terrain more closely, even when working up or down a hill. Why should this be necessary? Remember, the crane on a Valmet harvester is fixed to the cab. The operator will naturally tilt the cab to be more or less horizontal, meaning the head has now to move up or down if it is to travel parallel to the terrain.

One of Valmet’s aims is to use software to make their machines more profitable: “It’s not all about iron and oil,” we were told. Perhaps an example of what they mean is that, whilst the 360.2 head now cuts 12% faster, which should lessen the possibility of cracking valuable logs, MaxiXplorer can automatically drop them to the ground during cutting, to support them at this vital moment.