ZF dual-pinion electric power steeringEnlarge Photo
What’s largely been replacing them over the past decade—electric power steering systems (EPS)—make a lot of sense on so many levels. With current and an electric motor, mounted closely, providing the assist, they have small packaging; they’re mechanically simpler; they’re touted as more reliable; and they weigh a lot less. And because EPS only uses energy when you’re turning it boosts fuel economy and lowers emissions.
Steering might not affect ultimately how well a vehicle performs, but it certainly affects how much confidence you have behind the wheel—and how much satisfaction you get from the driving experience. While these systems work just fine for most owners, there’s been unease among enthusiast types for years—with claims that in some vehicles EPS yields an artificial, digital feel and unnatural weighting.
It’s rare that we get to take questions like this straight to a steering expert, an experienced engineer, or an industry insider. But at a recent ZF technical event we were able to just that. Here are excerpts of our very thought-provoking, nuts-and-bolts Q&A session with someone who fits all of those roles: Scott Montgomery, Systems Integration Manager at ZF Steering Systems:
Why does electric power steering elicit such strong and wide-ranging views (on how it should or shouldn’t be) when hydraulic power steering is generally taken for what it is?
It was always very difficult to get a good-feeling hydraulic system, but people became used to accepting some of the weird nuances of it. In general, hydraulic steering wasn't bad; there were some really bad systems and there are some really good ones.
And I think it's the same way with EPS. EPS started off 10 or 15 years ago, and the first systems on the market were bad; there's no discussion, they didn't feel good, they made all sorts of noises they weren't supposed to, and EPS became a four-letter word in the industry. Nobody wanted to touch it. Especially those OEMs that had tried it early on and got completely fried by it. It was really a fight to convince them that the new systems are actually a lot better than what you had in the past.