Stop boom bouncing, banging and breaking

BRANDON — Sophisticated sonar boom height controls are great with a uniform top crop surface.

However, an undulating surface will have those booms bouncing, banging and even breaking.

The problem is that these systems take a sonar reading from a high spot in the crop, then a low spot, then a high spot again, followed perhaps by a bare spot.

The system is built to respond to these differing heights, so that’s exactly what it does. If there’s a high spot, the boom goes up. If there’s a low spot, the boom drops down.

If there’s another high spot, the booms tries to get back up to what it thinks is the new correct height.

Meanwhile, the boom is taking a beating, as is the operator. And the boom is often three metres behind in its quest to apply product at the correct nozzle height over the target. The end result is a second rate spray job and possibly equipment damage.

Norac, the first North American company to use ultrasonic height control 40 years ago, has a new sonic boom control system that eliminates the constant boom battering.

The hybrid mode on UC5 and UC4.5 takes multiple ultrasonic readings with sensors mounted on the spray boom. Readings are taken from the top of the crop, mid-height plants and bare soil.

The readings are averaged to give the hybrid controller a virtual top of crop picture. The best possible boom height is extrapolated from those figures.

Subtle adjustments still continue on a second-by-second basis, as they did before hybrid mode was introduced, but the changes are now more gradual, according to Norac representative Craig Lester.

“Here’s how it works. You’re travelling across the field spraying at 24 inches and you suddenly come to a washout or lodged crop. Happens all the time,” said Lester.

“Your conventional ultrasonic system is looking for crop, but it’s disappeared. It takes control of the boom and the boom drops in an instant, before you can catch it. Well, the system is doing exactly what it’s supposed to.

“The problem gets worse when you’re back into standing crop because now the boom is way below the top of the crop and doesn’t know it. It can’t take a reading or lift itself up. So now you’re ploughing crop down and possibly bending the boom.”

Lester said an experienced operator who’s paying attention can usually catch it and lift the boom before it gets caught in the crop, but the faster the sprayer is travelling, the harder it is to make that save.

“When you have the UC5 or UC4.5 in Hybrid Mode, it’s designed to make that save for you. When the sensor loses the crop reading, it automatically stops the boom from suddenly dropping.”

Hybrid Mode is available on all current Norac boom height control systems and can be retrofitted to older systems.

The list price ranges from $6,900 to $15,000.

For more information, contact Lester at 800-667-3921 or visit

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