Setting a twin rotor rake to run sweetly this grass season could be the difference between producing high quality silage, free from contamination, whilst leaving a clean sward, compared to uneven swaths, mixed with dirt and debris, and cut grass on the ground after the rake has passed through.
With first cuts likely to be lower yielding than in some years, ensuring all material is raked into the swath, and presented correctly to the following forager or baler, is key. We spoke to Rhodri Jenkins, grassland product specialist at Kuhn UK, who highlighted some essential points for both twin and four rotor rakes this season.
Rotor height
Setting the correct rotor height is one of the most important settings on any size of rake. Operators should be looking for a finger’s width between the tine tip and the ground to achieve a good raking consistency, whilst preventing dirt and debris entering the swath. This may need altering if fields are rutted, which can be done via a manual crank handle or hydraulically on Kuhn’s four rotor GA models.
Rhodri stressed that when operators change settings on their rakes, they should be aware of how small adjustments can affect other settings.
“A small change to forward speed requires the rotor speed to be altered, while working width tweaks will impact rotor speed performance. Small adjustments can have a big impact on other settings.”
Rotor suspension can also help maintain rotor and tine height as it can increase or decrease downward pressure depending on the soil condition. For example, if the ground is wet, pressure can be decreased to allow the rake to glide over the wet spots, reducing the chance of tines contacting the stubble. Rhodri says this feature is standard on hydraulically driven four rotor rakes and on the four largest twin rotor Kuhn models.
Rotor speed
The ideal rotor speed is to match the forward speed to the rotor rotation. Too fast and the rotor will be flinging crop across the swath and out the other side, too slow will mean crop may be missed as the rotor can’t keep up.
Rhodri says producing a clean and airy swath is the aim, which may mean adjusting the PTO driveline to run below the 540rpm target to achieve the correct speed.
“What operators want to avoid is forming a hollow in the middle of the swath and two small rows on either side. This creates a lumpy crop delivery and, for balers, will lead to an uneven bale in the chamber as the swath isn’t uniform across its width.”
Swath width adjustment
An uneven swath can also be created due to an incorrect working width adjustment. If operators are noticing that the tines aren’t bringing crop in far enough, adjusting the swath width is the first place to start.
“If two small rows are being created, narrowing the swath width to form a complete row and adjusting the rotor speed to suit could be two small changes to produce better quality swaths.”
Rhodri continues: “Likewise, on heavier crops, it could be that a slower forward speed, wider swath width, and reducing rotor speed could deliver a fluffy swath with a consistent size.”
Again, swath width is hydraulic on four rotor rakes and a tractor’s droop setting won’t affect hydraulic flow. However, on PTO driven units this could be an issue, so operators will have to monitor it to ensure consistent output.
Kuhn’s cranked tine arm helps the machine gently bring crop in and release it, being kinder to swaths and preventing damage to the leaf. The cranked design means it has a higher release point than a straight arm, which means releases the crop quicker to form a square edged swath.
Similarly, a cranked tine means contact with the ground is always flush and doesn’t force the crop into the ground. The sweeping motion delivers a cleaner gathering of the crop.
Headland control
An essential part of raking is to ensure raked crop isn’t moved again, as this could easily allow contamination to creep into the swath and damage leaf structures. Headland control systems make this easy for the operator and can raise rotors into a high headland turn position, with up to 40 degrees of rotor tilt and 750mm of clearance possible on the Kuhn GA range.
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