Richard L. Parish | 4/4/2006 8:33:04 PM
Front-wheel-assist (FWA) is a popular option on many compact utility tractors, and it’s standard equipment on several models. It’s also available on some lawn and garden tractors.
When it’s engaged, FWA provides four-wheel drive.
"FWA substantially increases the cost of a tractor but provides some important benefits," says Dr. Dick Parish, an engineer at the LSU AgCenter’s Hammond Research Station. "On popular 28- to 30-horsepower compact tractors, FWA adds $1,100 to 1,600 to the price. What do you get for your money?"
Parish says using FWA generally gives better traction because all tires are pulling. This can be especially helpful when using a front-end loader, he explains, because the loader will transfer weight from the rear to the front, and FWA uses this extra weight for traction.
"When pulling a tillage tool or other implement with a heavy draft load, having FWA is often equivalent to having several more horsepower on your tractor," Parish says.
"One added benefit of FWA is that you don’t have to waste tractive force from the rear tires pushing non-powered front wheels though soft soil," he adds. "With FWA, the front tires pull themselves through. If you’re just mowing, there’s less advantage to FWA, since traction is usually not limiting."
The LSU AgCenter engineer says FWA may need more weight on the front axle than with a two-wheel-drive tractor.
"With two-wheel drive, the weight on the front axle is useful for traction when dynamically transferred to the rear axle under load," he says. "With FWA, the weight on the front axle is usable for traction even without weight transfer."
FWA front axles are heavier and stronger than two-wheel-drive axles. This means less extra ballast is needed to achieve the same front axle weight. The stronger FWA axles also are beneficial when using a front-end loader, since they are better able to handle the weight.
Without FWA, Parish says a tractor may resist turning, and the front tires may slide. With FWA engaged, a tractor will pull itself around turns with less skidding of the front tires. The overall turning radius generally is smaller without FWA, but turns are easier to make with FWA.
"The ability to make power turns without skidding the front tires is one argument for using FWA even when mowing," Parish says. "Some manufacturers offer FWA with turf tires."
Most manufacturers recommend disengaging FWA when driving with no load or driving in high gear on pavement. This practice will reduce tire wear.
"Front-wheel-assist can be a valuable option on your compact utility tractor if you use it for tillage or loader work, but it may not be worthwhile if all you do with the tractor is mow," Parish says. "If the ground is soft enough to need FWA, you probably shouldn’t be mowing."