The Roots type 3-lobed helical aluminum blower provides scavenging air at 3 to 5 pounds above atmospheric into each of the cylinder's intake ports, expelling the exhaust gases through four exhaust valves in each cylinder head. This produces a large volume of low pressure air, proportional to engine speed.
Engines with 12, 16 and 20 cylinders have two of these blowers, one on each bank of cylinders at the rear of the engine, above the traction generator. Engines with 6 and 8 cylinders have only one blower. The blowers are mechanically driven by a gear train on the power take-off end of the engine.
This page last updated 12-12-12