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Schultz asserts that powershift transmissions can also tackle finish grading. “A powershift transmission, when backed by a differential steering system, can give the level of maneuverability to larger tractors when finish dozing is a required part of the owner’s needs,” he explains. There is also a trend toward electrohydraulic controls that simplify operation. “All of our machines are moving in that direction.”

Komatsu America also equips its mid--size and larger dozers with powershift transmissions with torque converters. They are coupled with the Komatsu Hydrostatic Steering System for ease of maneuverability, according to Ed Warner. “A torque converter allows you to have that ‘umph’ you need when you initially need to load the blade or if you are digging a stump. You just don’t get that with the hydrostatic transmission,” he claims.

However, Brett Errthum argues that hydrostatic transmissions in the mid--size John Deere dozers are just as efficient as torque converter drives, plus they simplify operation. “In the past, hydrostatic dozers had limitations,” says Errthum.

“We have a long--term relationship with our component supplier to develop pumps and motors specifically for our application. Really, the breakthrough came in better electronic controls that help divert the power to where it is necessary.

We have been able to overcome what has been the traditional downfall of the hydrostatic transmission on a large dozer.”

John Deere dozers use a load--sensing hydrostatic system. “When they sense that a load is bogging the tractor down, they will actually slow down the hydrostatics,” says Errthum. “By slowing it down, you are going to get more pushing power.” There is no need for the operator to shift the transmission to compensate for the load. “With a powershift transmission, you generally have three speeds,” he continues. “We have an infinite range.