"NY" wrote in message
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"Dave Plowman (News)" wrote in message
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In article ,
TMS320 wrote:
Turning off the ignition will turn off electric power steering. Not what
you want to add to your list of surprises.

You can still steer the car with no power assistance. It will just be
heavier. But not so heavy you can't steer it to the side of the road. And
far safer than trying to stop the car on the brakes while on full power.

Yes I've driven my car a couple of miles, including changing lanes, coming
off a motorway and going round a roundabout, with no PAS when the fan belt
broke. It was heavy. I had to plan ahead and grip the wheel with both
hands to get more torque on the wheel, but it was not insurmountable. I
wouldn't like to try it in a coach or HGV, though :-)

Is the heaviness of the steering when PAS is disabled due solely to having
to compress the PAS fluid on the "wrong" side of the piston that gives
power assistance? Or are cars with PAS made with inherently heavier
steering (different castor angle)

Not castor angle so much as just the gearing between the
steering wheel and the angle of the wheels. A car with PAS
is free to have a more direct ratio because the force required
on the steering wheel wont be that high due to the power
assist when the engine is running.

to give greater precision and feedback to the driver, in the knowledge
that the PAS will more than compensate for this heavier (but more
responsive, more self-centring) steering.

Its more that the force required would be too high for normal
driving without the PAS with the more direct steering.

That’s why some yank tanks had a knob on the steering
wheel in the days before PAS. They had a much higher
ratio to minimise the force required on the steering
wheel but which has the side effect of needing more
turns of the wheel when parking etc.

I've heard two schools of thought about this.

IMO likely due to ignorance of the basics.