Case IH has become the first combine manufacturer to work with Canadian firm Redekop to bring its MAV straw chopper design to the UK market, forming part of a new Axial-Flow Xtra-Chopping package.
This move by Case IH is designed to optimise straw processing, distribution and breakdown to benefit subsequent crop growth.
With straw and stubble management becoming an increasingly important part of following crop establishment where minimum or no tillage systems are practised, the new package creates a finer chop and more even spread of straw, leading to faster decomposition and incorporation into the soil.
After two years of trials here, during which Case IH engineers have worked closely with those from Redekop to ensure the package’s suitability for UK conditions.
Xtra-Chopping will be an option for the flagship 240 series Axial-Flow models for the 2016-17 sales year, and can be retro-fitted to existing 230 and 240 series combines.
Xtra-Chopping retains the existing integral two-speed Case IH Magna-Cut 120-blade chopper, this being used as a discharge beater to pre-chop residue and propel it into the hood-mounted Redekop MAV chopper.
Internal brackets and deflectors are removed to expose the total internal width of the combine, and the Redekop MAV chopper is then fitted to the combine’s upper frame, with a new full-width internal chop-to-swath door also being installed, and crop deflectors fitted to the integral chopper concave.
Existing actuators and speed sensors are retained when the driveline from the combine to the Redekop chopper is installed and the fitment completed, with Xtra-Chopping then fully controllable via the combine’s AFS Pro 700 terminal. The rear access ladder is unaffected.
While conventional chopper design depends on the effect of the chopping blades to also eject the chopped material from the combine, Redekop MAV, designed for European conditions, consists of separate zones for chopping and spreading.
12-blade paddle fans
The patented design feature 12-blade paddle fans – 35mm blades for headers up to 10.7m (30ft) and 50mm units for wider cutterbars - at each end of the chopper rotor.
These generate maximum air flow velocities of up to 90mph (145km/hr), aided by specially-designed shrouds.
The airflow created helps to draw both the straw and the chaff through the chopper as it is ejected from the rear of the Axial-Flow rotor on wide-body 240 series models.
“This use of air velocity to carry the residue is the key to the presentation of the material to the conventional chopper blades in the zone across the centre of the chopper rotor,” says Case IH combine product specialist, Paul Freeman.
“Almost two thirds of the blades’ rotation is within a shroud to maximise its efficiency, and air is also scavenged from the cleaning shoe, drawing the chaff into the chopper so it’s mixed and distributed with the chopped straw.
“This airflow also helps to present the straw lengthways to the 96 reversible carbide-coated blades mounted in eight rows on the rotor.
"These operate at 3,250rpm and work in conjunction with an adjustable counterknife, helping to slice the straw longitudinally as well as conventionally.
“This finely-chopped material is then more easily ejected from the combine and blown down into the stubble across the full width of cut, an effect that’s aided significantly by the airflow created by the paddle blades.”
'Durability and longevity'
The tailboard vanes are independently-adjustable from the AFS Pro 700 terminal to allow the spread of chopped straw to be fine-tuned so that it covers the full cutting width of the combine, with independenet left and right adjustment.
“For combines operating cutterbars of 12m (40ft) and more, there is an MAV Plus+ option, which uses a rotor with forged ends running in larger 50mm bearings for even greater durability and longevity.
It also features larger fan/paddle blades which increase the air velocity to 150mph (240km/hr), plus specially-scooped tailboard vanes which help spread chopped straw and chaff across the full cutting width.”
The result, says Mr Freeman, is chopped residue that is taken into the field surface far faster and more evenly than material from a conventional chopper.
“The splitting of the stems lengthways as well as crossways allows moisture and natural soil bacteria to get at the straw’s internal structure and break it down more quickly."
"Worms are more easily able to pull it into the soil surface, boosting organic matter levels and providing the next crop with the best possible environment for germination, emergence and early growth.
"Meanwhile, soil nitrogen can be better utilised by the growing crop, rather than being locked up by decomposing straw.”
Xtra-Chopping will be an option for the flagship 240 series Axial-Flow models for the 2016-17 sales year, and can be retro-fitted to existing 230 and 240 series Axial-Flow combines.
