Hopping is for bunnies, not tractors. Besides being a nuisance, power hop can rob you of achieving top efficiency. Brad Harris, manager of global field engineering for Firestone Ag, outlines how to reduce power hop.
“Power hop can be reduced or eliminated on mechanical front-wheel-drive tractors in a five-step process,” he says. “It’s recommended that the MFWD tractor is equipped with duals or triples on the rear axles. Front duals or a front axle suspension are also beneficial.”
1. Properly weigh and ballast the tractor. A MFWD tractor should weigh 130 pounds per PTO horsepower, with 35% of overall tractor weight on the front axle and 65% on the rear. Set the front and rear tire pressures to the minimum, based on the correct axle weights using Firestone’s tire inflation calculator, Harris says. Then check for power hop. If it’s eliminated, no further adjustments are necessary. If not, proceed to Step 2.
2. Stiffen the front tires by increasing inflation pressure. On radial and bias tires, increase the inflation pressure to the maximum rated inflation pressure in the Firestone Data Book or the table provided by the tire’s manufacturer. Keep the rear tire pressure at the minimum recommended pressure. Check for hop and performance. If hop persists, proceed to Step 3.
3. Remove all front ballast weights. Keep tire pressures the same as in the previous step, Harris says. Check for hop and performance again. If power hop persists, proceed to Step 4.
4. Add liquid ballast to front tires only. Using appropriate equipment, install liquid ballast in all front tires to 75% normal fill. The valve stem will be in the 12 o’clock position. Keep rear tires dry, and check for hop and performance again. If power hop is still present, proceed to Step 5.
5. Seek assistance. If power hop is still present, seek assistance.
Other power hop solutions
Power hop on four-wheel-drive tractors can be reduced or eliminated in four steps, Harris says. Find details in the Firestone Data Book. You can also watch a YouTube video from Firestone below.
The goal is to properly weigh and ballast the tractor, Harris says. A four-wheel-drive tractor should weigh 110 pounds per engine horsepower with 51% to 55% of the total weight on the front axle, and 45% to 49% on the rear axle.
In this case, the goal is to stiffen the rear tires, not the front tires like with MFWD tractors. The steps outlined by Firestone Ag walk you through how to do that safely by starting at minimum inflation pressure and increasing rear inflation 6 pounds per square inch at a time, not to exceed maximum allowed psi in the rear tires.
Other manufacturers have developed their own solutions. Scott Sloan, ag products manager for Titan and Goodyear farm tires, explains their philosophy.
“Adding ballasts and adjusting to proper inflation pressure for the weight of the ballast and implement are some ways to avoid power hop,” he says. “However, that’s what Goodyear’s Low Sidewall Technology tires are designed to do without the need to ballast or frequently adjust pressures.
“The larger rim diameter of LSW tires helps dampen the effect of power hop before it spirals into loping that requires you to slow down or stop.”