Imagine getting every 15th hour of tractor operation free. With diesel fuel prices hovering between two and three dollars per gallon, that's an appealing proposition for most producers. Nevertheless, it's a claim that Tony Kosolofski, marketing specialist and sales engineer for Challenger track tractors, is always ready to explain.

“With wheel tractors, a certain amount of wheel slippage is necessary to protect the drive train and prevent compaction,” he says. “Most of the time, wheel tractors exhibit slippage of 8 to 12 percent, which varies with the application, the tires and the soil type. Unfortunately, few producers adjust tractor ballast as conditions change. Of course, excess weight also increases rolling resistance of the tires, basically robbing any power or efficiency that would have been gained by reducing slippage.

“In contrast, operators typically experience slippage in the range of three percent or less with the Challenger Mobil-trac system,” he continues, pointing to the long footprint and five- or six-axle design. “That means that five to nine percent of the drawbar horsepower on a comparable wheel tractor is lost to slippage. So for about every 15 hours you operate a Challenger track tractor versus a wheel tractor, you'll essentially get one hour free.”

Kosolofski explains that over the course of a 300-hour season, that could amount to 210 acres of more timely production. That figure, he says, is based on an average 10 acres/hour times seven percent (less slippage) for approximately 0.7 more acres per hour.

“Less slippage can also mean a substantial fuel savings,” he adds. “If you burn 20 gallons of diesel per hour at just two dollars per gallon, a seven percent improvement at a rate of $40 per hour comes to $2.80 per hour. Totaled over 300 hours, it equates to $840 in annual fuel savings.

“Of course, those figures don't take into account the fuel efficiency of the new ACERT Technology engines in the MT700B and MT800B Series tractors or Challenger's Tractor Management Control (TMC) system,” he adds.

According to Kosolofski, peak power on the new Cat engines occurs at around 1,700 to 1,800 rpm, which means operators can often gear up and throttle back on loads that don't require PTO operation. In the meantime, the TMC allows the operator to achieve a preset ground speed by automatically varying the engine speed. However, the “constant ground speed” function will also make automatic downshifts under high load conditions to prevent engine stall. Once the load reduces, the TMC system automatically up-shift to return to the desired ground speed.

“The operator can also select the ‘maximum output’ mode, which assists by automatically shifting to keep the engine in the peak power range where horsepower is maximized,” Kosolofski adds. “This can be done manually, of course; but the TMC does it much quicker and automatically, which tends to save fuel in the long run. With fuel prices accounting for a greater portion of production costs, that's music to most producers' ears.”

For more information on the Challenger MT700B and MT800B Series track tractors, or the Challenger brand's full line of agricultural products, visit