Schaeffler's energy-efficient ball-screw drive is being utilised on the electromechanical steering system for the Volkswagen Tiguan. Schaeffler supplies the ball-screw drive to Volkswagen, as well as a toothed rack, which is partly designed as a spindle on which the drive is located. Ball-screw drives are used to transform rotary motion into linear motion through a direct coupling between the drive element and the output element.In the Tiguan, the ball nut is driven by a servomotor, which is linked to the ball-screw drive via a belt. These low-friction, low-noise ball-screw drives play a role in helping to improve a vehicle's fuel consumption and reduce CO2 emissions. As well as offering the driver optimised handling, the latest electromechanical steering systems can also reduce fuel consumption by as much as three per cent compared to conventional hydraulic steering systems.
An advantage of an electromechanical steering system over a hydraulic one is that the servomotors require energy only when specific steering manoeuvres are carried out, while hydraulic pumps need to maintain hydraulic pressure at all times. This means that pumps and feeds are no longer required on an electromechanical system, which reduces the space required for operating the steering system. Other customers of Schaeffler's ball-screw drives include automotive supplier TRW. The ball-screw drives are also used on vehicles manufactured in the US by Volkswagen, Ford and BMW. The aerospace sector is another user of high-precision ball-screw drives, which are often found in an aircraft's tail-steering system.
