As automakers push to make their entire model lines more fuel efficient, anything that can assist the cause is open to possibility. Recently, spokespeople for Nexteer Automotive, a driveline company that has it’s origins in Delphi and General Motors, announced that it plans to replace conventional hydraulic assisted power steering, with new electrically assisted systems in half-ton rigs within the next three years. Electric power steering systems are already used in small cars, hybrids and SUVS, but until recently the technology simply wasn’t advanced enough to cope with higher axle weights and loadings typical of larger vehicles. However that has now changed as advances in vehicle electrical systems and stronger rack and pinion steering setups have made it possible to offer them in 1/2 ton full-size pickups. General Motors has already offered electrically assisted power steering in its Chevy Silverado and GMC Sierra Hybrids, and now it looks set to extend the system to their conventional counterparts, it will be interesting to see how and/or when Ford and Chrysler will adopt it on their F-150 and Ram trucks.
Unlike hydraulic power steering systems, where an engine driven pump is used to pressurize hydraulic fluid to assist turning the steering linkage – and is constantly in operation when the engine is running, including idling and straight line acceleration or braking, Nexteer’s electric assisted system, uses an electric motor which drives a ball-screw that only operates when the vehicle is actually turning, thereby reducing parasitic loss from the engine and improving fuel efficiency. According to Tony Dodak, manager of Nexteer’s rack and pinion based EPS systems, adopting this technology will result in around a four percent improvement in overall fuel economy on your average full-size truck.
However, at this early stage there are still some sizeable hurdles to clear. For one, the software isn’t advanced enough to compensate for changes in vehicle ride height or tire size, meaning that should an owner modify his/her truck, it might result in some interesting handling characteristics. Secondly, EPS systems can only work on rack and pinion setups at present. This poses a problem on larger 3/4 and 1 ton pickups as well as commercial chassis cabs, which used recirculating ball steering systems, since the parasitic load is too high to cope with the vehicle’s 12-volt electrical system. But given that EPS is being recognized as a major development in the world of half-ton pickups, it’s probably only a matter of time before a more advanced version is fitted to heavier rigs.