Communication between the engine and transmission further optimizes the shift points and prevents overspeeding the engine. "If the driver goes downhill, it's automatic. It will make sure he keeps [the machine] below the maximum engine speed so he doesn't have to worry about overspeeding," says Samera.
This communication has also enabled Deere to introduce Event Based Shifting on its D-Series. "Deere's transmission allows operators to shift from forward to reverse or reverse to forward without the operator needing to use the clutch," says Jeff Rowan, product marketing manager for motor graders at John Deere. "For example, if an operator is in reverse in sixth gear and wishes to shift forward to third, he or she only has to move the shift lever accordingly. The machine will smoothly slow down, reverse direction and accelerate into the desired forward gear. The transmission is always protected and the engine is automatically prevented from stalling."
On Volvo's G900 models, the electronic transmission provides a shuttle shift feature that enables simple straight-line forward to reverse shifts (and vice versa), without using the inching pedal or stopping first, and from any speed, notes Brian Lowe, product and communications manager, Volvo Motor Graders. "This reduces cycle times and operator fatigue by eliminating both inching pedal and brake use when changing directions," he explains.
"An operator can combine Volvo's exclusive memory feature with both the Autoshift and shuttle shift features," he adds. This enables easy cycling between forward and reverse gears without shifting or clutching. "The operator simply selects what gears best suit his application and the electronics look after the rest. You couldn't do that before."
Caterpillar has improved its electronically controlled ECPC transmission by electronically engaging and disengaging the clutches between gear shifts. "Prior to the M-Series, we only made changes between direction shifts," says Porter. "Now we're incorporating that technology between gear shifts, so it's going to give us a much smoother-shifting transmission than we've ever had before."
In addition, the company provides standard Variable Horsepower or optional Variable Horsepower Plus. Both deliver power in 5-hp increments as the transmission gear selection increases, and subtracts only 5 hp with each downshift. This ensures adequate power in each gear, says Dan Gillen, product support supervisor, Caterpillar Motor Grader Product Group.
"As you're upshifting, you can either continue to load the machine with more material or move the same load at a faster ground speed, which increases your productivity," he explains. "When you come into a steeper grade or you encounter heavier material and the transmission needs to downshift, you will have adequate power to hold the load or maintain desired ground speed, no matter what gear the transmission is shifting to."
Impact on in-cab controls
Advances in electronics have also permeated inside motor grader cabs.
The most visible example is the electrohydraulic joysticks introduced on Caterpillar's M-Series. This configuration eliminates the conventional control console and steering wheel, replacing them with a pair of three-axis joysticks that control all machine, drawbar, circle and moldboard functions. In addition, all auxiliary functions are controlled via electro hydraulics.
Caterpillar's patent-pending electro hydraulic joystick design also provides some automated functions. "For instance, once the operator has finished a turnaround, they simply push a button on the left joystick and that will return the articulation joint to the center position," says Porter. "The only way we're able to do that is through electrical communication with the hydraulics."
While other advancements may be less obvious, they have produced substantial benefits in machine controllability. Consider Volvo's Power/Speed Engine Mode Switch on the G900 models.
"The operator can switch at will between a 'Power' and a 'Speed' setting to actually change the engine's torque curve when it's running in either of its two lower horsepower ranges," says Lowe. When set to Power mode, the grader develops additional low-end torque, and engine speed is "capped" at 1,900 rpm in the low- and mid-range power setting for improved fuel economy. In the Speed setting, or automatically when a higher gear is selected, the engine changes its power curve for more efficient operation at higher ground speeds.