Mowers and foragers get most attention when it comes to the grass harvest, but rakes play a key role and need careful operation. Jane Carley reports...
High capacity foragers, balers and wagons offer considerable output potential, but also come with a price tag and running costs to match, so it is worth considering whether the rest of the grass harvesting outfit is performing well enough to get the most out of them.
One such piece of equipment is the rake, says James Duggleby, marketing manager, Krone UK: “The rake is often overlooked, but plays a key role in preparing the swath for the harvesting machine.
“Rake purchasers often ask what is the best machine to match their chosen mower. It is more important to consider what it is feeding.”
Rakes, he points out, should produce a swath wide enough to fill the width of the pick-up of the harvesting machine.
“If the swath is too narrow for a baler, you will get too much crop in the centre of the bale and a poor shape, while chop consistency will suffer on a forager. Forage wagons are forgiving, but you may as well utilise the full width of the machine and get a more consistent chop.”
DIFFERENT types of rakes can produce different results, says Mr Duggleby. He says: “A two-rotor rake gives a wider swath width as the working width increases, but fourand six-rotor rakes can produce a swath width independent of their working width.
“This enables you to make sure you can pick up enough crop without making too wide a swath width for your harvesting machine.
For contractors raking in front of a variety of machines through the season, there is always going to be a degree of compromise to what is the ideal rake.”
Producing a regular box-shaped swath to get an even mat of crop into the forager is the main objective, he points out.
“It wants to be consistent, not full of lumps or loose bits, which will prevent the forager working to its best,” he says.
The ideal raking outfit, Mr Duggleby suggests, is one that is reliable, set up correctly and operated skilfully.
GRASS equipment is increasingly automated, and rakes may be set up and operated from a control box, IsoBus terminal or even a joystick. This makes tasks such as setting the tine working height easier.
“Aim to adjust the rake for each field, which is made easier by features such as electronic rotor height control, adjustable on the move. This helps with time pressure from the rest of the foraging team compared to getting out and adjusting the rake manually, and allows you to fine tune it to the conditions,” says Mr Duggleby.
“One of the most important settings is the height of the tines above the ground. Too low and soil can get into the swath, bringing bacteria with it.
“Stones can also be picked up which will blunt blades on a baler or forage wagon, and pose a danger to livestock,” he says.
“But set the tines too high and forage will be left on the ground, which is not only wasteful but can also rot into the following sward.”
He adds that it is easy to check the height is correct - lines left in the soil or dust flying showing it is too low and a mat of crop left behind, too high.
Tine height also varies on fourand six-rotor rakes, with the rear rotors often needing to run lower as they carry more crop, causing the tines to bend back further.
MR Duggleby comments that driving technique is also important, matching forward speed to rotor speed and the crop conditions.
“In a heavier crop, go slower, and in a lighter crop you can go a bit quicker, but watch out for the crop blowing over the top of the swath and hanging onto the tines.”
Rotor speed is dictated by pto speed on mechanically driven rakes.
“A visual check will tell you if it is right, but generally a higher pto speed is needed in a heavier crop, and a lower pto speed should be selected for light crops, such as hay and haylage.”
On some rakes it is necessary to adjust the cam track to achieve the desired swath width and shape.
IN undulating conditions the rake may benefit from an extra pair of bogie wheels, with a six-wheel layout riding better over rough or bumpy ground by pivoting at the rear.
Cardanic suspension is also helpful to let the rotor pitch from front to back and side to side, following the ground well in ridge and furrow.
“We also have the ‘jet effect’ on Krone rakes which puts the back of the rotor down first, preventing it from digging in,” Mr Duggleby comments.
When setting the rake up, the position of the bogie wheels should be checked and the side pitch of the rotor adjusted.
“Rotors should not travel parallel to the ground as when the tines are loaded, the gap between the tine tip and ground will increase. Pitching them slightly to the inside will help keep the gap equal.”
AS explored in Farmers Guardian’s May 3 edition, maintenance is also key to rake performance, with checking tyre pressure regularly being an easily forgotten point.
“If the tyres run flatter on one side than the other, this affects the rotor height,” he explains. “Also replace any worn or damaged tines; if one of a pair is snapped it will not carry the crop over as effectively, while a bent tine arm should be straightened as it affects tine height.
“Finally, pay attention to routine greasing.”
MR Duggleby adds that swath quality is about more than just the rake.
“Pay attention to tedding quality – if you put lumps into the harvested swath you are not
necessarily going to be able to get them out with the rake.”
Good technique also goes back to the mower, when operators should avoid driving over the mown crop and leaving lumps in the swath.
“Mower size in itself is not crucial, but the key is to avoid bottlenecks. If you have a high capacity mower and rake, then you need a tedder to match.”