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Ballasting: The Great Balancing Act
Ballasting isn’t new and it’s not all that sexy, but it’s wildly important.
When it comes to getting the most out of every pass you make across the field, every dollar you spend on equipment and fuel, and every inch of soil you work so hard to preserve, ballasting is critical.
Ballasting has always been important – that’s not the issue. So every once in a while, it’s important to review the rules and best practices to ensure you’re being as efficient as possible.
“Ballasting itself really hasn’t changed all that much, but how much you’re ballasting has,” says Scott Sloan, ag product manager at Titan International.
If Randy Taylor, former Oklahoma State University Extension machinery specialist, has anything to say on the subject, it’s that farmers, when ballasting, need to put serious thought into the main purpose a tractor will serve after it’s first purchased. “The key is to have your tractor set up like you want it to start, because the odds of you changing it later aren’t high,” he says.
Even though Taylor isn’t seeing growers reballasting or changing inflation pressure based on the implements in use, that doesn’t mean they shouldn’t be. “As tires have gotten bigger, that ballasting power has become more important,” says Sloan.
Understanding the Ultimate Goal
Getting as much horsepower as possible transferred from the engine to the ground is the end target. Accomplishing that requires either adjusting existing weights or placing additional ballast either on the front or rear of the tractor. The goal isn’t to have 0% wheel slip. In fact, engineers prefer a slip rate between 3% and 10% for wheeled tractors, Sloan says. However, some university Extension engineers say that slippage between 10% and 20% is the sweet spot.
When tire slippage is in the 5% to 10% range, it’s usually undetectable, Taylor says. “Generally when that wheel slip gets up above 15% or so, it becomes obvious that you’re slipping.”
Having too high a slippage rate means spending more time than necessary in the field and wasting money on fuel as the tires are forced to spin more, says Firestone field engineer Brad Harris.
In the past, you had to go to great lengths to measure slippage by marking the tire, determining wheel circumference, driving the tractor a specific distance, and plugging the findings into a formula.
Today, you have to make little to no effort to measure slippage. Usually, all it takes is looking at the monitor in the cab to see the percentage of slippage.
Tire inflation Just as Important as Weights
According to Harris, 95% of farmers aren’t able to adjust tire inflation in the field. However, some companies are equipping new tractor lines with that capability. Fendt, for instance, developed an integral tire pressure regulation system that allows you to adjust inflation on-the-go.
“You can drop a bunch of weight in there, but if your tires are overinflated, you’re actually causing yourself more harm,” says Sloan. “If you manage inflation pressures, you can eliminate a lot of compaction concerns.”
Heavy tillage is the hardest on tractors, but even planting can pull harder on the machine. This, in turn, pushes ballasting high up on the priority list. For implements like disk rippers, the goal is always to keep slip to the minimum discussed before. Yet, there are risks to adding weight to a tractor.
“You’ve got to be careful,” says Sloan. “If you put on too much weight, you’ll run into compaction.”
Harris says one of the hardest things he has to tell farmers is that they’re adding too much weight.
Newer tractors seem to be equipped with a slew of suitcase (case) weights on the front axle. It can look impressive, but Harris has seen growers over-equipping their front axles with weight because of the new style of tractor. In some cases, 22 case weights will fit on the front axle. But often you need only three or four weights on that axle to be properly ballasted.
“We have to be able to design tires that are able to take the extra weight and to run inflation pressures that aren’t too extreme and cause soil compaction,” Harris says.
What to Do
Before heading out to the field, check the owner’s manual for the weight recommendation for the horsepower of the tractor.
Sloan’s rule of thumb is assigning 90 to 110 pounds per hp. when it comes to total machine weight. Then, make sure to put the recommended amount of weight on the correct location (front vs. back) of the tractor.
“For front-wheel-drive tractors, you’ll want weight on the rear axle of the tractor,” Harris says.
Taylor suggests putting 35% to 40% of weight on the front axle of front-wheel-drive tractors. For four-wheel-drive tractors, Harris likes to see 51% to 55% of weight on the front axle.
After putting the weights on, set inflation pressure based on the axle load.
What About Liquid Ballasting?
Putting calcium chloride directly in the wheels is one strategy, but it isn’t a very popular one today unless you are trying to use the cheapest option. “Liquid ballasting takes away from the radial way that tires perform. The sloshing around deters the radial effect of the tire,” says Scott Sloan of Titan International.
According to Sloan, the farther west you travel, the better chance you’ll have of seeing farmers using liquid to ballast their tractors. Randy Taylor of Oklahoma State University Extension hasn’t seen many farmers in Oklahoma still opting to ballast with liquid lately. “It’s messy. Certainly if you’ve got a flat and you’re liquid ballasting, it’s a mess,” he says.
Although Sloan doesn’t believe in liquid ballasting, Taylor isn’t convinced that the concept is all that detrimental. “From a pure traction standpoint, it doesn’t matter – weight is weight,” says Taylor. When it comes to tractor dynamics, he thinks using liquid could have some negative effects. One of those is helping to create power-hop issues.
It’s important to remember that liquid can be even more challenging to adjust for different implements. It’s a choice between deadlifting case and wheel weights or spending time extracting liquid from a tire. The choice is yours.