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Buyers’ Guide: Flex-Wing Rotary Cutters

Tackle tall weeds with these versatile machines.

Cleaning up weeds, tall grass, and brush along field edges before harvest requires a durable, hardworking machine. That’s where flex-wing rotary cutters shine. Sometimes called a Batwing mower (Batwing is a registered trademark of Woods) or a Bush Hog (a registered trademark of Bush Hog), a flexible-wing rotary cutter can make short work of brush and weeds.

When choosing a unit, first look at the width. Three common sizes are 12, 15, and 20 feet wide, with the most popular being the 15-foot unit. Each rotary cutter requires the right amount of horsepower, balance, and ballast. A lighter-duty 12-foot unit works well on utility tractors of 50 to 80 hp. The popular 15-foot models work best on tractors 75 hp. and up. The 20-foot models require higher horsepower and are used more by road crews and farmers in the Northern Plains.

The machines are extremely versatile. “Most farmers buy them for roadside maintenance or to clean up around row crops before harvest,” says Tom Elliott, product marketing manager for John Deere Small Ag. “Livestock folks use them to clip pastures. By clipping the weeds and tall grass, it leaves more forage for the livestock to eat and reduces insect issues such as flies that cause pinkeye.”

How to select

When choosing a flex-wing rotary cutter, match it to your chores and terrain, says Rob Dewey, vice president of engineering for Woods, based in Oregon, Illinois. “Look at the types of material to cut. If you are cutting pastures and brush, you can use a lighter-duty mower. If you are shredding cornstalks or wheat stubble, you need a heavier-duty cutter.”

If you are mowing CRP land, you may need a heavier model for small tree saplings. Lighter-duty rotary cutters can handle tree saplings with 2-inch-diameter limbs. To handle a 4-inch limb, you need a heavier model.

“Look at your terrain,” says Dewey. “If it has ditches, waterways, and obstructions, choose a heavier cutter.” 

Also, consider the number of hours you will use the cutter per season. “Larger farmers use them for 200 hours or more per year,” says Dewey. “If you are only going to use it for 20 hours, a lighter cutter should work fine.”

Costs vary, but expect to pay $15,000 to $23,000 for a 15-foot model. The heavier 20-foot models can cost $30,000 or more.

bushhog-mower
Bush Hog 4815 Rotary Cutter

Buying points

Ease of maintenance is a key buying point. Make sure the gearbox is serviceable and it’s easy to check the oil. Look at the grease points. The ease of slipping power shaft clutches is important, says Elliott. “You need the ability to release the clutches, shedding rust and condensation that might stick the clutches together. If you get into dirt on a bank or terrace, you don’t want to just power through; the PTO shaft can be damaged.”

Most producers will want a stump jumper pan that holds the blades, says Elliott. “If you get in an environment with small stumps, the pan skims over the stump and doesn’t damage the cutter.”

Most units have a smooth-slope deck so water and material won’t pocket on the top causing the deck to rust. Clean off the cutter deck after every use so weed juices don’t corrode it.

A deep deck chamber and tall side frames “will allow you to handle more cut material and drive through deeper grass with less horsepower,” says Dewey.

Most companies offer a crop shredding kit with twin swinging flat blades for handling cornstalks or wheat stubble.

kubota-mower
Land Pride RC2512 Rotary Cutter

Tires

Tire technology has changed. Solid laminated tires used to be popular because they were puncture-proof. However, when tractors pulled the cutters on blacktop at 30 mph, the tires would shred apart on the road. Today, used aircraft tires and severe-duty ag tires are standard issue. The 18-ply used aircraft tires are almost puncture-proof, says Dewey. “You can even have them foam-filled so they last even longer.”

Severe-duty ag tires were designed to be just like airplane tires, but without the 200-mph speed rating. They were developed because rotary cutter manufacturers were at the mercy of the aircraft industry. Once again, foam-filling severe-duty ag tires makes them virtually indestructible. 

“If you are not going down a highway, laminated tires are fine,” says Elliott. “If you are moving from farm to farm and going up and down the road, you need a severe-duty tire.”

Tips

Replace the cutting blades every two years. When they wear down from a square point to an arrow or a needle point, the blade is worn out.

Pull the cutter out on a flat surface, says Dewey. “Make sure the machine is level side to side and 1 inch lower in the front than in the rear. It should be nose down toward the tractor. That way, it will take less horsepower to run. If it is down in the back, you will cut the grass twice.”

Check the oil level and the lug nuts. Check for flat tires and anything that rattles. Check the blades. Make sure there are no large cracks or grooves, they are sharp enough to do the job, and they are mounted securely to the blade carrier.

deere-mower
John Deere HX15 Rotary Cutter

Safety

Inspect the terrain to make sure there are no washouts or deep holes that could upset the tractor. Check for large rocks and debris, especially if you are mowing near a roadway or a farmstead where something could be thrown out from under the rotary cutter. Every flex-wing rotary cutter should have shielding, usually a chain curtain in the front and back or rubber belting. Safety packages on the machines are standard across the industry, says Dewey, who is chairman of the rotary cutter safety council.

“All companies participate, and we take it very seriously. Do not operate these machines within several hundred feet of bystanders,” he says.

Besides front and rear safety chains, the PTO shafts have safety shields, gearboxes are shielded, and there are safety chains for towing.

Finally, always lock up the wings when towing.

Learn more 

Bush Hog: bushhog.com

John Deere: deere.com

Land Pride: landpride.com

Rhino: rhinoag.com

Woods: woodsequipment.com

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