Emerging Giant: CVT engines

Emerging Giant: CVT engines

Abstract

                  The continuously variable transmission (CVT), which Leonardo da Vinci conceptualized more than 500 years ago is now replacing planetary automatic transmissions in some automobiles. The job of the transmission is to change the speed ratio between the engine and the wheels of an automobile. So the transmission uses a range of gears -- from low to high -- to make more effective use of the engine's torque as driving conditions change. Unlike traditional automatic transmissions, continuously variable transmissions don't have a gearbox with a set number of gears, which means they don't have interlocking toothed wheels. By comparison, a continuously variable transmission is a study in simplicity. The simplicity and stepless nature of CVTs make them an ideal transmission for a variety of machines and devices, not just cars. The toroidal CVT system -- replaces the belts and pulleys with discs and power rollers. A hydrostatic CVT, uses variable-displacement pumps to vary the fluid flow into hydrostatic motors. Continuously variable transmissions are becoming more popular for good reason. They boast several advantages that make them appealing both to drivers and to environmentalists.