Metering disc helps corn planter seed canola

Reduced static | Great Plains device uses pressurized air for improved spacing

Implement companies have been struggling to keep up with the recent trend of seeding canola with a corn planter.

Great Plains has a unique way of dealing with the challenge.

The company recently introduced a new metering disc, brushes and seed tube designed specifically to turn its corn planter into an accurate canola planter, according to Mike McClure, engineering manager at Great Plains.

“To begin with, the system uses pressurized air rather than a vacuum. We blow the seed against the disc,” McClure said.

“One of the main advantages of positive air is you don’t have to worry about minor air leaks in the system. With a vacuum or negative air, the slightest leak throws off your singulation and spacing. Even a very small leak can cause the seed to fall off the metering disc. With positive air, you can tolerate a few minor leaks and still have the same accuracy. The compressor makes up for the loss of pressure. It’s far less sensitive, almost foolproof.”

McClure said the disc is 11 inches in diameter with 250 holes. It runs at the relatively low speed of 20 to 35 r.p.m. Higher r.p.m. creates greater centrifugal force and more static electricity, which can knock the lightweight canola seeds out of their pocket. The low rotational speed helps keep the seeds in place at the recommended ground speed of 5.5 m.p.h.

Static electricity is the enemy of canola seeds everywhere, so Great Plains went to great lengths to find the most static-free material available.

“We found a special compound for the bristles and metering disc and the seed tube,” he said.

“It causes the least possible amount of static. We have three brushes inside the unit to cut off airflow or hold seed in place just before discharge. This is one of the worse places for static. The new seed tube is engineered to be totally smooth inside. There’s no hole for the seed sensor. The material is transparent so the sensor beam shines through the sides of the tube. It’s just as accurate as having a sensor hole, but it gives the seed a perfectly clean route.”

McClure said the new Air-Pro static free system was already available for small seeds such as sorghum and sugar beets. Making adjustments for canola was mainly a matter of fine tuning the bristle material.

As of next month, the new metering system will be installed on all Great Plains Yield-Pro planters with Air-Pro metering.

For more information, contact McClure at 785-823-3276 or visit

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