MILWAWKEE, Wis. — Big articulated tractors roll power to the ground over a pair of fixed axles.
Any balancing that occurs from front to back comes in the form of soil movement as torque is transferred to dirt.
Situations such as power hop are typically managed by adding fixed ballast, increasing tire pressure, reducing the throttle and operating speed or lessening the load.
Smaller, fixed frame tractors of up to 400 to 500 horsepower have had the option of a suspension, but articulated machines have not.
For next year, John Deere will offer the option of a front suspension on its largest machines from 520 to 620 h.p.
Putting more weight onto an already heavy machine and increasing tire pressure results in greater soil compaction.
The pressure compounds the problem of creating a smaller tire-to-field contact area and negates the improvements in tire technology, which allow for lower pressures under high loading without tire damage.
Joe Speas of Deere’s Waterloo Tractor Works in Iowa said the challenge was to deal with the load without transferring it to the ground in an unstable manner.
“And if you have ever been in a tractor that is experiencing severe tire hop, well, let’s say you either put on the seatbelt or get off the throttle,” he said at a Deere dealer release of the 2015 machinery models.
“Now put the torque a 620 h.p. engine produces through a transmission and a set of drives, down onto the soil. I think it might be bad for the little plants that want a start there.”
Kevin Juhl of Deere said the new suspension system begins operating long before the machines start to noticeably hop through the field or down the road.
“The system begins managing wheel slip (traction and load) before the operator might identify it,” he said.
“And it lets you take advantage of lower tire pressures, putting (fewer) pounds onto the soil.”
The company calls its new system Hydracushion.
It is built around a hinged, front drive axle and a pair of large hydraulic cylinders, three accumulators and a censor system that measures the load on each axle. The system buffers the movement as the load shifts between axles and cancels the loading wave that develops.
The result is a more even loading of the tractor’s tires and reduced wheel slip.
For more information, photographs and video of the system at work, visit producer.com.