Shifting solution said to improve fuel savings

New state-of-the-art shift synchronizers are said to reduce fuel consumption and improve gear shifting ease for 9-spd. and 14-spd. gearboxes. The synchronizer, from Oerlikon Graziano, is being offered to the heavy truck market.

According to the company, the new synchronizers save fuel in two ways: by optimizing the shift to minimize torque interruption and by reducing steady-state drag torque in the transmission. They combine the durability and performance of Oerlikon Graziano’s existing Long Life synchronizers with a new internal activation system, the use of optimized clearances and lubricant paths for higher efficiency.

“Most new transmissions carry over existing synchronizer designs which limits the scope for efficiency improvements,” said Andrea Serra, product manager, synchroniser and powershift design, Oerlikon Graziano. “Our new synchronizer technology offers a step-change improvement in fuel efficiency for the next generation of heavy duty transmissions.”

The new synchronizers are configured in single and double cone arrangements, each with the same external geometry to allow great flexibility in transmission design, the company said. In all, four different synchronizer specifications are used on the 14-spd. transmission and three on the 9-spd.

By increasing the speed of a manual shift, Oerlikon Graziano has been able to reduce the torque interruption, keeping the engine at optimum efficiency for longer and reducing engine transients to save fuel, it said. Whichever gear is selected, large differences in rotating speed can exist across the other synchronizers. According to Oerlikon Graziano, with a conventional design this leads to significant drag losses which impair efficiency, but the new synchronizers greatly reduce this effect to further improve fuel economy.

The new synchronizers improve the shift process during three distinct phases. Prior to synchronization, the integrated activation system provides optimized load characteristics to give improved consistency and outstanding durability, compared to a standard design.

The second phase, synchronization, has been shortened by the use of multi-cone technology, best-in-class friction materials and the optimization of geometries and tribological properties.

The third phase, from synchronization to engagement, has been improved by incorporating new internal features allowing smoother travel of the sliding sleeve, avoiding blocking problems and providing a more friendly engagement feel to the driver, and finally making this solution even more attractive in applications which are usually manual shift with air assistance, so any shift problems can immediately become obvious to the driver.

“Our priority is to develop transmission technologies that allow our customers to introduce more capable and competitive vehicles, whether for cars, trucks or off-road applications,” said Serra. “The new synchronizers will support the next generation of truck transmissions with reduced fuel consumption and improved driver convenience.”

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