Electric Steering / no hydraulics

[Latexman]

I noticed last night that Mrs. Latexman's new van doesn't have the usual power steering fluid reservoir. Electric steering! Now I know why the steering is so effortless. But some of the "feel of the road" seems to have been lost. I guess this is the future given all the news about self-driving cars. Anyone else seen this?

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

 

[JohnRBaker]

My 2013 GMC Terrain has electric steering and I have no complaints (driven 70,000 miles so far). One note of interest, at least in 2013, this was only on Terrains that had four-cylinder engines. If I had gotten the six-cylinder version, it would have been equipped with conventional, hydraulic-assisted power-steering. That being said, I suspect that electric steering will become the norm in a few years.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

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[dgallup]

Oh yes, purely electric steering assist has take over the market. Only a few hold out purest sports cars still have hydraulic assist and there are some hybrid systems with electric hydraulic pumps. The early pure electric systems were widely reviled for killing all all steering feel, newer systems are supposedly better. I'm not so sure that the road testers haven't just recalibrated their own standards since there are virtually no new hydraulic assist vehicles for comparison. It's all part of the creeping electrification of cars in the name of fuel efficiency. None of my vehicles are new enough for such nonsense and I glory in the consumption of hydrocarbons by large 400+ hp infernal combustion engines.

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[zdas04]

I've driven several rental cars with electric steering and I guess I lack the sensitivity to tell the difference. It has always been fine.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[waross]

Electrons are cheaper than oil.
I don't see it as difficult to design in some proportional band in the steering mechanism. Basically the strength of a small spring. The stiffer the spring the more road feel.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[GregLocock]

I've been working on EPAS for about 12 years. It is still expensive compared with HPAS (which has one expensive valve, one cheap valve, the cheapest pump known to mankind, and a few hoses). The lack of road feel with EPAS is a real thing, basically the electric motor is permanently coupled to the steering via a mighty reduction gearbox, and to sense road inputs you have to back drive the gearbox and motor. To some extent you can use friction compensation in the strategy, but this leads to the feeling that the steering is being motored which is unnerving. As the tire approaches saturation the steering goes light (for well understood reasons) which is a characteristic we like, so a simple self centreing spring characteristic would not be desirable.

From an engineering POV EPAS offers a lot of nice features, but if your aim is to have great steering feel then you are still better off with a /good/ HPAS (and good tires). It would seem that people who pay money for new cars by and large prefer the mpg and other benefits of EPAS to HPAS.

Cheers

Greg Locock


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[rapt]

I had a rental car in Europe a couple of years ago that had electronic steering. I think from memory it was a Renault but could be wrong.

Cornering was ok. Once you started to turn the steering whee, the computer seemed to figure out that it should let you think there was some resistance. What I did not like was the computers idea of road feel when going in a straight line. To get any feel, you basically had to turn the wheel slightly to create some resistance. Otherwise there was no road feeling through the steering wheel. There was a little indicator that seemed to suggest which way you should lean on the steering wheel based on the computers input from the wheels. I prefer that my hands do that for me!

Hated it and check these days when booking a car to make sure it does not have it. I suppose eventually I will have to give in, but by then my car will not have a steering wheel anyway!

 

[GregLocock]

OEMs have been releasing HPAS cars with no on centre feel since 1950 (hallo citreon), if not before. EPAS just made it easier to screw up.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[waross]

Full hydraulic steering is common on industrial equipment. You don't really need "road feel" when driving a tractor/loader/back-hoe at 30 kph.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[rapt]

Actually it was a Fiat 500 (L I think, like a small SUV).

 

[SomptingGuy]

One benefit of EPAS over HPAS is that it doesn't stall your engine when it's cold and you are using a lot of lock to get out of a parking place. Maybe that's more to do with the powetrain control module of that car, but it was one of the "features" I don't miss.

Wasn't there some issue with EPAS units burning out when being held on full lock?

Steve