BASF's Ultramid A4H nylon is used in a plastic worm wheel being fitted on the new Golf and the Audi A3

BASF's Ultramid A4H nylon is used in a plastic worm wheel being fitted on the new Golf and the Audi A3

BASF has claimed a first in the use of a plastic gear wheel in electric power steering units of medium-sized cars. A plastic worm wheel driven by a power-assistance servo-motor made from BASF’s Ultramid A4H nylon is now being fitted on car models such as VW’s new Golf and Touran and the Audi A3.

The gear wheel is part of an electric power steering developed by German automotive systems maker ZF Lenksysteme. This is a joint venture between Robert Bosch and ZF Friedrichshafen. BASF said electric power steering is eventually expected to replace conventional hydraulic systems. This is because electric units are more compact and, unlike hydraulic systems, only operate when turning assistance is required and so save on fuel. The plastic worm wheel must be capable of transmitting large forces at temperatures between –40°C and +120°C.