Wheel Slip

If your tractor wheels are slipping and spinning in the field, you’re wasting time, fuel and money.

Randy Taylor is an extension machinery specialist at Oklahoma State University. He says wheel slip happens when the tires are turning faster than the ground speed of the tractor. When you're pulling something, the tires should spin a little bit. It protects against overloads that could damage the power train. If there's too little slip, the tires are anchored to the soil because of too much ballast. You'll waste power and fuel trying to move the tractor through the soil.

Depending on the soil type and conditions, you'll get peak efficiency with a wheel slip between 8-and-15-percent. Taylor says there's a way to calculate this.

"Usually you might measure it by marking off a distance and going that distance and putting a mark on the tire, and you go the distance and count revolutions under no load, and then you come back and do it under load," says Taylor.

If there is too much slip, the tires spin excessively and result in energy loss. For every one-percent past the optimal slip, you lose one-percent in productivity and energy efficiency.

One way to reduce excessive slip is to lighten the load.

"Say for instance if you're pulling a box blade and your tires are spinning, what do you do? You kind of lift the box blade up a little bit so it doesn't pull as hard and you'll quit slipping. The other option is you add weight to the tractor," he says. "If it's a small percentage of the time, you know, the task that tractor's used for, then I'm probably not going to worry about wheel slip a lot because typically you're not going to put weight on and take it off for tasks. That's not feasible for most folks to do."