|Aircraft engines are changing to adapt to the tighter environmental regulations. One of the resultant developments has been the geared turbofan. Currently, the most famous ones are the PW1000G from Pratt & Whittney and the Ultrafan from Rolls Royce.
These two engines have a planetary reduction gearbox between the fan and the low-pressure shaft (2). This allows them to run at a higher rotational speed, which helps reduce the number of stages in the low-pressure turbine and low-pressure compressor.
In manufacturing terms this gearbox brings gear production to the forefront of engine production.