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Dashing through the fields

Dashing through the fields

Copyright photo: Stara S/A Indústria de Implementos Agrícolas

March 2015


Stara’s new Imperador agricultural sprayer rides as smooth as a car, even over rough terrain. A hydrostatic drive makes this comfort possible.

When the diesel engine of an agricultural machine stalls for the fifth time in a row because a wheel has bogged down in the mud, farming becomes anything but fun. Atila S. Trennepohl, Vice-President of Brazilian agricultural equipment manufacturer Stara, is well acquainted with farmers’ problems and needs. “They don’t want to have to continually concentrate on their driving, but on their real work – such as evenly spreading fertilizer or sprays on the plants. To make that possible, we decided to go with a hydrostatic drive from Rexroth when we were developing our self-propelled Imperador sprayer.”

Hydrostatics for a smooth ride

Field conditions in Brazil are particularly challenging: It rains a lot. The ground is wet and soft. Although the fields are mostly in the plains, the individual wheels regularly need to overcome short grades of up to 30 percent on account of innumerable troughs and depressions. “Driving a mechanical chain drive with clutch and shift under these conditions demands great skill and constant concentration on the part of the drivers. They need to watch the ground and constantly clutch and shift, clutch and shift,” Trennepohl explains. Thanks to the hydrostatic drive, this is no longer necessary in the Imperador. “The sprayer drives like a car with automatic transmission.” So farmers can now roll sedately over their fields on cruise control at a constant 25 kilometers per hour. Maximum load regulation via a DA valve ensures that the diesel engine doesn’t stall even under heavy strains – such as climbing a steep grade.

Less maintenance, greater yield

The hydrostatic drive allowed Stara to design the Imperador with four-wheel drive instead of the usual chain-driven two-wheel drive. “That has two advantages; it enabled us to make the sprayer larger, so that it can now carry more spray. And it makes turning at the end of the field easier, because the turning radius is made smaller by the greater steering angle,” says Trennepohl. A further advantage of hydrostatic drives is that they entirely eliminate the need for constant adjustment of the drive chain and other maintenance chores. “Just change the oil filters now and then – that’s all!”

The hydrostatic drive is not only convenient and low in maintenance but, according to Trennepohl, results in better yields: “Since you don’t have to shift gears, the diesel engine speed is always constant, and thus the spraying pressure as well. This ensures an even distribution of the spraying agent and, ultimately, a better harvest.”