Electric water pumps (was) alt charging cont sw

[Greg Hermann]

>Good points on cooling, Greg.  There is no need for an electric power
>steering pump, TRW has already designed electric power steering two ways.
>One with a motor on the steering shaft and another with a motor and ball
>screw directly on the rack.  Peak current draw is high but of short
>duration.
>
>Gary Derian <gderian at oh.verio.com>

I can't help but feel like these units would be about equally inclined to
go into meltdown in "difficult" situations as an electric powered winch is
when you work it hard on a 4x4! I prefer hydraulic or PTO driven winches,
and think that I would always opt for hydraulic on the power steering, too.
The "power density" with hydraulics is just tremendously higher.

Since there is no real load on the pump when the servo valve is not asking
it to do anything, I really think that a variable disp. pump is not
necessary. However--reducing the servo multiplication on power steering
with higher vehicle speeds is another story. This is VERY worthwhile!

Regards, Greg
>
>>For the power steering pump, I suspect that a variable displacement, vane
>>type pump (or swash plate type variable displacement pump, if you wish)
>>would give the variability you want for less weight, more simplicity, and
>>greater overall efficiency than an electric drive.
>>