Automotive Engineer

Lamborghini will use a seven-speed automated manual transmission, developed by Oerlikon Graziano, in its new Aventador sportscar. Lamborghini claims that the transmission allows for gear shifts in as little as 50ms.

The vehicle’s 6.5-litre V12 engine produces 515kW of power and 690Nm of torque, so neither a conventional automated manual transmission (AMT) nor a dual-clutch transmission could cope with the power output and meet the handling requirements.

A conventional AMT uses the standard H shift pattern of a manual gearbox, and gears are selected by sliding selector rails that lie parallel to each other. But the system is slow as the actuator engaging the desired gear has to wait until the crossgate actuator has selected the correct rail.

Lamborghini wanted a quicker system for the Aventador, so Oerlikon Graziano and its partner Vocis developed an independent shift rail (ISR) system.

Claudio Torrelli, head of product development at Oerlikon Graziano, said: “In the ISR transmission, there is no cross-gate motion and consequently no cross-gate actuator. Instead, each rail is operated directly by its own actuator. One rail selects either first or reverse, one third or fifth, one second or fourth, and one sixth or seventh.” The design means that no two sequential gears are on the same shift rail until the last change into top gear. As a result, the system can begin to move the rail for the next gear while still withdrawing the previous one, allowing for faster gear changes.