ok, so I cleaned the PCV valve...

on the freeway. any speed above crawling, basically. hell, even
crawling, if its in a straight line.

ive got no PS on my 98 civic CX, and the only time i wish i had it is
during multi-point parking maneuvers. not that i need to make many,
since its got a pretty tight turning radius.

some cars are switching to an electric PS pump. makes sense, in a way.

 

Like I posted to Boz, I realize the hydraulics aren't needed when cruising (=
steady speed, pretty straight line driving), but one can't have this and also
the ready maneuverability, too. I'm having a hard time seeing a design where a
PS pump wasn't always running yet also ensured safety.

Maybe you guys aren't making an engineering argument but instead are "just
saying" that maybe there's a way to save some power via another PS design of
some kind?

I have driven and I think owned at least one car without PS, and yes, it's not a
big deal. Just big enough for me to make sure I always have PS in the future.
;-)

I don't readily see a gain in efficiency, as the electric PS pump has the
intermediary of the alternator etc. driving it, and this costs efficiency. But
maybe the electric PS pump can vary its power output in a way more appropriate
to the driving needs at the moment.

Ships use electric motors to drive their hydraulic steering fluid pumps, but
that's probably simply because it would not be practical to run the steering
pumps off the propeller shaft.

 

Yikes to both.

I know vaguely what a "slug" is. It was still being taught in my college physics
courses, though it rarely if ever occurred in my engineering courses. I've heard
of the "poundal" (somewhere) but would have to look it up in my conversion
booklet to nail it down.

True. A Kg or cm are not heard to get a handle on.

Caroline
"A pint a pound the world goes 'round."
(Speaking of rules of thumb for conversions)

 

The Honda 3 & 5 door Civic in Europe (USA Civics, I think are all
hydraulic systems) use an electric power steering system.
There are no hydraulics, it's basically a big electric motor directly
driving the steering rack (in parrallel with the steering wheel in case of
electrical failure). It is still an assist system, it is NOT steer by
wire.

So the motor is only powered when the rack needs to move. Most drivers
don't seem to notice the difference.

 

The advantage that the electrically driven PS has is that when there is
little or no 'assistance' required, the electric motor is under a very
light
load and, consequently, draws only a small amount of current.

Hydraulic PS pumps (correct me if I'm wrong), always deliver their rated
output volume per minute at the rated pressure whether it is going to
drive something or just dumped back into the reservoir.

It's for the reason I gave above.

 

Yeah well it was important to remember when sweating over exams.

A poundal was to a pound as a Newton is to a Kg. It's mentioned here
http://www.ex.ac.uk/Projects/trol/dictunit/notes3.htm#force and is included
in the conversion calculator tables.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

Yes I understood that and the Civic Si sold in the U.S., which is the U.K.
Type S, has the "direct" electric system. The Euro G.M. mfrs call their
system EHPS... Electro-hydraulic power-assisted steering.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

But there's not much load on the pump when it's just recirculating the
fluid anyway - some mechanical drag I suppose.

As noted elsewhere some Euro G.M. models use this kind of system with an
electric pump. I've no idea how it works but when I drove one, a Vauxhall
Astra, I could not hear the pump switch on and off - some kind of variable
speed pump?

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

I agree.

snip

Mike wrote

I gather you mean you didn't hear the motor switch on and off. FWIW, on ships,
the RPMs of both electric motor and pump shafts stay constant. But the pump is
variable displacement, responding in proportion to where the rudder is IIRC. The
result is smooth response. The variable stroke pump used is called a "Waterbury
pump." No idea whether the Vauxhall Astra has such a pump. It's The little on
the net I see on the V Astra suggests the motor turns completely off. But this
contradicts what you think you heard.

Re the power requirements of a strictly electric-drive PS system:
After seeing Boz's post on the no hydraulic, all electric motor driven PS
system, I googled. As it turns out the claim is the all electric-driven PS
system is more fuel efficient by around 5%.
http://ca.autos.yahoo.com/030820/11/ugrz.html claims its simpler too. (And it
does sound simpler: No fluid hoses. No pump. No belt.)

A fuel savings of 5% does sound reasonable (though puny). I forgot how efficient
electric motors are. So if the PS motor is not running all the time, like Boz
and Mike suggested, yes there's a fuel savings. I suppose this all
electric-drive PS system relies heavily on electronics. I guess the parts are
probably more expensive to replace but last longer(?) and help other parts to
last longer, like a lot that's gone electronic over the decades with cars.

 

Hmmm, what I meant was that I could not hear any switch on/off of the pump
motor based on steering load but wasn't sure if that was happening or not -
it very well might if the motor could switch almost silently. I'm not sure
what's possible engineering-wise here. It was a rental car so I was not
interested in plumbing its mechanical intricacies.

I'm still awfully wary of EMSs. It always seems to me that the more
sophisticated they make household appliance controls, the less reliable
they become... dishwashers, washing machines etc.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

While I have a less experience than you in car specifics (among other areas), I
have the same feeling about this EMS (electric motor steering?). For me, I think
it might be prejudice against change and maybe having to learn something new
(all the electronics in the EMS).

On the surface, the link above certainly seems to me to make some good points
about the simplicity of EMS vs. a hydraulic PS system.

On the third hand, I've also seen at least one media report that talks about all
the electronic gadgets in loaded, new cars and how these cars may be spending
more time in the shop, not less, compared to cars 15 years or so older.

I'm keeping an open mind on EMS and will keep studying it, especially maybe its
reliability reports in something as simple as Consumer Reports annual April car
system reliability tables.

Of course, over the last few weeks, having recently nailed down and fixed all
the itty-bitty oil leaks on my 1991 Civic LX; given its great fuel mileage; now
also having my fancy, "proven" crankshaft pulley holder toy... uh, tool; and
looking at, at worst, a new clutch in the next few years, I'm thinking the new
Toyota Echo I have been eyeing is now five years or more away. We'll see if
Toyota has EMS by then. Or maybe Honda will wise up and start making Civics with
1.5 liter engines again and EMS.

 

EMS (Electro-Mechanical Systems) in general - thus the reference to
dishwashers etc. The old systrems with the rotating dial worked almost
forever; the new umm "programmable" systems always seem to be failing, with
replacement of the entire control unit for ~$300. the only repair option.

Yep and it would be nice when working on the car to err, lose the pulley,
hoses and belt. something always seems to get in the way of something
you want to do. OTOH hydraulic systems are now well understood and last
very well with very little leakage problems.

There are some good articles on the Web, with a good illustration here
http://www.egr.msu.edu/autoweb/Class/Proj_2001/backlash/I_bginformation.htm
of Honda's EPS as used on the NSX/s2000. The biggest potential problem I
see with it is mechanical wear and lubrication to avoid it. The obvious
advantage of a hydraulic system is that the rack is pushed by a hydraulic
ram so there is very light stress on the rack & pinion and related
bushings. I can foresee, e.g. people who go to bigger wheels/tires, taking
a factory EPS beyond its design limits easily and breaking the
electro-mechanical drive.

Yep and from what I gather, VW is a prime example here with all their
glitches in the electronic gadgetry in recent models. I also remember the
days when you could limp home for hours with a failed/failing alternator or
broken belt - all the battery needed to do was supply spark to the engine -
no more.:-(

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

C wrote
snip but comments noted

True, from what I've seen. I note I'm not re-building my 13+ year old power
steering pump anytime soon, after all. Seems the silly leaks were all fixed by
more basic seal replacements, like valve cover grommets (ouch). We rarely see
reports of power steering leaks here at the newsgroup, too.

After briefly studying the drawing at the above site and considering how
power(-assisted) steering rack and pinion systems work, I agree with you. In
sum, an EMS has more mechanical gearing power transmission than a hydraulic
system. That extra mechanical gearing power transmission will require more
design "attention."

I am figuring the engineering design factored this in. E.g. the gears are made
of higher strength (fatigue and yield) steel than the ordinary, hydraulic PS
rack and pinion? No idea.

Time will tell, I suppose.

These net reports are certainly optimistic about the trend being towards EMS
power steering.

Maybe some manufacturer bias is more than a wee bit present.

(And a 42 volt electrical system, per the site above? I wonder if those students
aren't being a bit optimistic as they talk about "engineers" wanting to drive
the water pump and A/C compressor with electric motors. Surely this has been
considered in the past. I will have to think about why such a switch has not
been made.)