FARGO, N.D. – A side delivery hay rake that’s hefty enough to handle rocks and roots would simplify the process of clearing new land.
David Trevilyan builds that machine.
The Australian farmer, inventor and manufacturer attended this year’s Big Iron Show in Fargo to introduce his Multi Farming Systems Rock Rake to North American farmers.
The rake he displayed, which is the first he has shipped to this continent, has 10 giant steel pronged pinwheels to windrow trash on newly cleared land.
The aggressive mechanical mammoth handles a swath up to 22 feet wide, leaving a windrow of sticks, stones and broken bones that the dozer left on the surface after it passed.
When Trevilyan built the first version of his pinwheel rake more than 25 years ago, he thought it would be used as a cultivator on already-cropped fields.
However, Australian farmers saw the pinwheel as an efficient way to quickly put new ground into crop production.
Bush clearing in that country is similar to how it’s done in North America: trees are cut and removed and roots burned.
Rather than pay for expensive dozer time to push and pile, producers can hook their Rock Rake to an appropriately sized farm tractor and rake the rubble into long windrows.
Wind and weather are allowed to do their jobs, and the remaining rocks can then be hauled away when convenient.
David’s daughter, Kris Trevilyan, said the 10 pinwheel Rock Rake is the second smallest unit their company builds and requires only 120 horsepower when it’s scratching trash on hard ground.
“But on soft soil, where you want more penetration for rock removal, you may need 150 to 300 h.p.,” she said. “It also depends on how wide you run the frame. If there’s a light load, you can extend it out to the full 22 feet. If you’re windrowing a lot of heavy material, you’ll need to pull it in so it’s narrower.
“You’ll know when you’re biting off too much of a load when the pinwheels start jumping.”
She said tractor power requirements depend on ground speed, swath width, amount of trash to be moved and depth of penetration.
Swath width is adjustable on the go from the cab.
The two 30-ply jumbo jet tires support the frame’s back end and are as close to puncture-proof as the Trevilyans could find. They also provide steering adjustment through a pair of phased hydraulic rams.
Working in heavy trash, the operator selects a narrow angle so the rake doesn’t cover as much ground. This gives each pinwheel a smaller patch on which to concentrate.
The operator swings the two rear tires out when approaching relatively clean ground so the machine widens and gathers up a wider swath.
The tractor towing point is at the centre of the frame to prevent sideways crabbing. The rams connect directly to the rear wheel mounts so there are no tie rods ends.
Kris said there’s no reason to worry that the prong tips can remove significant topsoil from knolls and slight rises.
Pinwheels allow loose soil to flow through, while trash is fed from wheel to wheel toward the back, thus creating a windrow coming out of the last pinwheel.
“Each pinwheel is on it’s own jumper (pivot and arm) so it follows its own course across the soil surface. Plus the frame has a hinge point at every five pinwheels. So you can work in hilly areas and not cause soil erosion or too much soil movement.”
She said field operations are similar to haying with a side delivery rake, but a big difference is that the rock windrower can be fitted with an optional flamethrower at the back to ignite windrows.
“The tractor is actually sitting inside the swath of the machine, so you always go counter clockwise,” she said.
“You continue going around the field moving that windrow onto the dirty ground. The steering hydraulics plug into your regular tractor hydraulics. We have phased rams, so they work together to steer the rear tires. The truck tire at the front is on a caster, so it follows the tractor.”
In transport, the Rock Rake is an end-pull implement with a simple straight tow bar attaching at the front caster wheel. The tractor hitch folds into the frame and the rear wheels are set to the straight forward mode during transit.
The prongs on the pinwheels are made of mild steel. New lengths of common bar stock are welded on when the old ones wear or break.
Kris said efficiencies designed into the company’s implement line include using the same NTN 2.25 inch bearings on the Rock Rake, no-till drill and deep ripper.
The exposed forward-facing bearing on the Rock Rake takes all the abuse and has an extra protective cover to keep sand and grit out of the bearing.
“Those bearing housings are the only castings on our Rock Rake. David hates castings of all kinds because you can’t fix them, but there’s no choice with bearings,” Kris said.
“And he hates grease nipples because they take time and money and are messy. The bearings on our machines only need to be greased once or twice a season.
“The other thing David hates is springs. They do so much damage, especially to drill frames. As they compress they become stronger, so when they release they give a tremendous jolt to the frame. That causes short-term breakages and long-term stress and fatigue.”
The eight wheel Rock Rake handles swaths up to 18 feet in width, the 13 wheeler does swaths up to 29 feet and the 18 wheel machine handles swaths up to 41 feet wide. The 24 wheel rake on the drawing board will handle swaths up to 53 feet wide.