High p.s.i. in transit, low p.s.i. in the field

Agricultural tires roll easy and stay cool roading; then they get dirty in the field without crushing it

LANGHAM, Sask. — Bigger, faster and heavier are the words to describe the trend in farm equipment both on the road and in the field.

But bigger, faster and heavier puts tremendous demands on tires.

The solution to the problem has been obvious since the first pneumatic tires went on tractors 90 years ago: inflate to higher pressure for roading and lower the pressure in the field.

The theory is fine, but putting it into practice is a nuisance, says Ken Brodbeck, vice president of technology at Precision Inflation. He was at Ag In Motion to show off his company’s leading edge central inflation system for ag equipment and explain why variable inflation has become essential.

“We all know that a tire’s worst enemy is low pressure while traveling down the road,” says Brodbeck.

“So what we do at Precision Inflation is design and build systems that inflate the tire to the optimal road pressure so it rolls easy and stays cool. You get better fuel economy and longer tire life.

“But you don’t want a hard tire when you get to the field, so we drop the pressure down to the optimal level for the work the tire is performing.”

LEFT: No drilling is required to install the system. Air enters the black ring fixed to the axle housing, then transfers to the rotating blue ring. The air fitting on the blue ring accepts a rubber hose that runs out to the air fitting on the outer surface of the wheel. The key to making it work is the long-lasting reliable seal between the fixed black ring and the revolving blue ring. RIGHT: The Precision Inflation computer automatically drops the pressure to nine p.s.i. for field work, giving the Michelin Axiobib four bars on the ground plus a longer footprint. | Precision Inflation photos

Brodbeck said the idea of installing a system to control tire pressure is not new. The technology has been around for decades, but with varying degrees of success.

He said Precision Inflation is owned by Michelin and is one of the oldest players in the game. Last year, Michelin bought PTG, a German company known as a global leader in central tire inflation systems (CTIS) and re-named it Precision Inflation.

PTG’s specialty has been CTIS for large slurry tankers and the tractors required to pull them, so it is a leading edge innovator dealing with the most difficult challenge in tire management.

Brodbeck said the Precision Inflation system is highly automated. It takes over when you plug directly into the ISOBUS system on the tractor, so there’s no need to add extra boxes or controllers.

Farmers operating with other types of CTIS systems say the time to deflate before entering the field is long. Brodbeck said the Precision Inflation system typically takes two minutes to bring the tires from road pressure down to field pressure.

“We drill a new 9/16 in hole in the wheel, tap it and install a separate threaded valve,” he said.

“The wheel and tire stay on the tractor the whole time — no need to dismount. Next we install a two-line air system on this valve. Our second air line opens and closes the valve. Other systems use an electric solenoid, but we think air is more reliable in the field. So now it’s under control of the computer. It takes over and automatically raises or lowers the pressure to whatever setting you want.

“In order to take full advantage of CTIS, Michelin has developed a whole new line of tires called EvoBib to work with central inflation systems. The tire has a different shape to the tread pattern on the road, so with higher pressure, the shoulders literally lift off the road so you’re rolling on the crown. That makes the tire roll easier and gives you better wear. In the field, with lower pressure, the shoulders drop down to engage the soil and give you not only a wider footprint but also a longer footprint for better traction.”

Brodbeck said he has a customer who installed the system on a big 4×4 tractor and a seed cart. He programmed the controller to automatically adjust tire pressures as the load in the seed cart changed so he always has the maximum size footprint.

The system lists for US5,000 for two tires, assuming a compressor is already installed on the tractor.

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