At first glance it seems that it is impossible to keep on improving combine harvester outputs but manufacturers keep proving otherwise.
It is no easy task thanks to a number of physical constraints. European combines can’t be any wider if they are to travel legally on the highways. They can’t be much higher or they snag power lines and they shouldn’t sensibly be much heavier if following crops are to have a chance.
Even header width must be near its maximum. Apart from anything else spreading chopped straw beyond 40ft is hardly feasible.
Where now then? One small-scale American firm has taken a farmer-designed articulated chassis combine into limited production but it seems unlikely to suit European conditions.
Enter stage left then the engineers from German firm Claas. Their forebears designed the company’s first combine back in 1936 and for many UK farmers their first combine was a trailed Claas Super or a self-propelled Mercury.
Progress in the post war years was of course rapid and for Claas the introduction of the Lexion range in 1996 might have been seen as reaching a plateau. In the intervening 20 years however there has been incremental change and it hasn’t just been confined to model numbers and cosmetics. For example the introduction of Terra Trac rubber track technology has helped keep combines on the move in tricky conditions.
As the next step Claas has introduced its 2016 Lexion 700 range with the focus on a number of new features and improvements to the cleaning and residual grain separation systems, the straw chopper and the electronics.
The company has also followed a well-trodden path much used by manufacturers and rolled out to smaller models some premium features previously only available on top-of-the-range models. This is a good low-cost way to enhance the value of the more basic models.
A key feature is further development of the systems that surround the Lexion’s hybrid threshing system. The claimed result is further increases in performance and operational reliability.
In addition to these new features the range will include a new hillside Montana version of the Lexion 750, which like the larger Lexion 760 Montana will automatically self-level on slopes of up to 17 degrees. Very handy for some Scottish conditions.
Under the bonnet, the latest series combines will be powered by engines which meet ultra-tough Tier 4f emission regulations. Currently the Lexion range is powered by either Mercedes Benz or Caterpillar engines, but all the latest models will be powered by Mercedes Benz engines, with the exception of the Lexion 760 which will be fitted with a 12.5 litre Perkins.
The top-of-the-range 780 and 770 models will be powered by the latest 15.6 litre Mercedes engines, with maximum power outputs of 625hp and 585hp respectively, compared to 598hp and 551hp on current models. Lexion 750 and 740 models will be fitted with a 10.7 litre engine.
Increasing performance while using less engine power is a worthy target. It saves fuel and makes more power available for other components. One example of this is the Dynamic Cooling system introduced two years ago on the larger models and now to be fitted on the 750 and 740. This provides “cooling on demand”, so only ever provides the cooling output that is actually required by the machine. As a result, power requirement is reduced by around 15hp and up to 20hp on higher powered machines.
The package incorporates a charge-air pressure cooler, hydraulic fluid cooler and engine radiator. Unlike standard cooling systems, which are vertically mounted, the Dynamic Cooling package, complete with the variable fan and a 1.60m diameter filter, lie horizontally behind the engine to achieve a larger surface area.
This draws clean air from above the combine into the radiator, which is then forced downwards over the engine, before exiting through louvres in the side of the engine bay. This creates a curtain of air that flows down the side of the combine to actively prevent dust rising. This not only ensures that clean air is being continuously drawn into the engine, but that the whole engine bay area is cleaner.
All five Lexion 700 models feature the Claas Hybrid threshing system, which uses the APS primary threshing system to remove the easily threshed grains, leaving the main threshing rotors to extract the remaining harder to remove grains.
On 770 to 740 models, the two Roto Plus rotors are each fitted with five concaves, with the 780 having six, which incorporate hydraulic cover plates or “bomb doors” on the first two segments to alter the separation area.
A Claas feature for many years has been the clever 3D system which levels the grain on the upper sieves when working across slopes. Now a new 4D cleaning system takes this a stage further by using a slope dependent rotor cover plate control and automatic fan control.
Essentially 4D specified combines will have a third pair of rotor cover plates split in two. These are automatically adjusted according to the lateral and longitudinal angle of the combine, but with the current separation and cleaning output also taken into account.
As the combine angle changes, the cover plates on the up-hill side of the rotor is automatically opened or closed. When the combine is working directly up or down the slope, the 4D system will also automatically adjust the fan speed dependent on the angle, reducing the wind speed when working uphill and increasing the speed on the way down, in addition to adjusting the lower sieve.
To accommodate the potential increased capacity possible due to the higher engine power and the 4D system, the top-of-the-range 780 now features a 13,500-litre capacity grain tank. The discharge rate from the tank is 130 litres per second, which means that the tank can be emptied in less than two minutes.
With more minimum tillage now taking place an even spread of chopped straw and chaff across the full cutting width of the combine is essential for efficient incorporation and breakdown in the soil. Cutting widths of up to 12.3m and generally bigger crops of straw have made a new straw chopper an essential.
The chopper drum has been increased in width by 5cm. It seems a small change but as a result, crop flow into and through the chopper is claimed to be more uniform, resulting in a more even chop length. The larger chopping drum also improves acceleration of the chaff, resulting in a wider spread pattern. Instead of being hydraulically driven, the radial spreader is now mechanically driven, which means that it maintains a consistent speed and reduces fuel consumption.
To avoid blockages Claas has developed a new Automatic Crop Flow control which monitors and compares the rotation speed of the engine, the primary and the secondary separation systems. The operator sets a preferred “slip level” and when this is exceeded the system will alert the operator, while at the same time shutting down the cutterbar drive and feederhouse, engaging the cutterbar brake, disengaging the unloading auger and reducing the cruise control speed to the minimum.
The old trailled Super of the 1950s couldn’t do that.