Power-assisted steering is moving into smaller cars.
These cars are becoming heavier and more difficult to steer, and electric-assisted steering is lighter and smaller than hydraulic systems.
'An electric power-assisted steering system weighs about 7kg compared with the 12-14kg of a typical hydraulic one,' says Brendan Connor, managing director of TRW LucasVarity Electric Steering Ltd.
The company is a joint venture set up to develop and manufacture an electric power-assisted steering system at a LucasVarity factory in 2000. Capacity will be 2.5 million units per year.
TRW owns 51 percent and LucasVarity 49 percent.
The system 'requires the high-speed, safety-critical control which we have already developed for braking systems and which most steering suppliers do not yet have,' says Connor.
LucasVarity Electric Steering will sell the unit in a module, not as a component.
'TRW will make the steering rack,' says Connor. 'Steering columns will be made, for example, by the Krupp company Presta. We'll assemble the complete modules close to the vehicle assembly facility.'
The module can be installed on the assembly line in four minutes, he says, compared with 'the 20-25 minutes it takes to mount a typical hydraulic system, because of the pipes, belt and pulley that have to be fitted around the engine.'
Electric and hydraulic power technology cost about the same, he claims.
In an electric power-assisted steering system, an electric motor and electronic control unit replace the mechanical hydraulic system.
The parts can be mounted on the steering column, the pinion or the rack, depending on where acceptable space and temperatures can be found. The first LucasVarity electric steering product is mounted on the column.
Outside of the joint venture, TRW has a rack-mounted electric power-assisted steering system ready for delivery to a European manufacturer of a sporty car starting in 2000, says James Handysides, TRW vice president and general manager for electrically assisted steering.
Delphi Automotive Systems has a system ready for delivery in November to a European manufacturer of a city car. Nick Franklin, Delphi Saginaw's Paris-based manager of marketing and planning, says the manufacturer is not GM. Franklin expects the system to become standard within two years as the vehicle builds up to its full 250,000 annual output.
Delphi Saginaw will be supplying systems to at least three vehicle programs in the next three years, Franklin says, including the Opel Corsa.
The technology has been available on small (600-800cc) Japanese cars for more than 10 years and has been fitted to cars in Europe since 1996.
The first European vehicle on the market with such a system was the Renault Twingo in 1996. Developed in collaboration with Koyo in Japan, the Twingo's system provides assisted steering up to a speed of 65kph.
The Koyo system provides 'as good a performance as the hydraulic power-assisted units on top-of-the-range vehicles such as Audis, Volvos and the Renault Megane,' says Yannick Lacour, director of strategic planning at SMI, the Koyo subsidiary near Lyon, France.
He says manufacture will move from Koyo in Japan to SMI within six months.
Another Japanese manufacturer, NSK, has supplied steering units to the GM Corsa models with a 1.0-liter engine since about a year ago. The same system may also be introduced on the 1.2-liter version.
Cars with larger engines are likely to use a more powerful electro-hydraulic system, like that found on the new Astra, says Mike Imeson, Vauxhall spokesman.
The new Fiat Seicento is also to be offered with an NSK system as an option.
The Astra system uses an electric motor to drive the hydraulic pump rather than driving it off the engine.
Thus, the pump runs only when power is needed, and pump and motor can be relocated.
Opel spokesman Karl Mauer says this saves 0.2 liters of fuel per 100km.
Both Delphi and TRW supply the units.
The Citroen Saxo and Peugeot 106 also use an electric/hydraulic combination, with the electric motor being supplied by HPI, another Koyo company.
Marc Boucque, r&d spokesman at PSA/Peugeot-Citroen, said PSA will use the system widely starting in 2000, when performance and cost are at an acceptable level.
Now, he says, customers dislike the feel of the steering wheel after experiencing the set-up.
Ford also believes current systems are unsatisfactory.
'We are not dismissing the technology but we have evaluated 12 of the systems that are currently being developed or in production. None provided a satisfactory dynamics performance,' says Ulrich Eichhorn, manager of vehicle dynamics at Ford's small and medium vehicle center. 'They feel artificial because they suppress feedback from the road.'