Hello Sean & PIC.ers,
..
>How can a
>car sit still on a hill with the engine holding it from rolling
>backwards? The engine, of course, needs ...
..
The engine spins the input shaft of a `torque converter', this is
incompletely filled with hydraulic oil.
At output shaft speed=0, there is some torque developed when the
engine is running, so your car can creep into the one in front of you
at the traffic lights :)
..
At high RPM of both halves, the oil is held in the perimeter of the
vanes, and more torque is possible. Less energy waste too, I suppose.
..
In another life, many moons ago, I worked in a coal mine where
popularly there were machines fitted with a drive train that was usually:
3ph. induction motor -> `fluid coupling'  -> load.
`Load'  being rubber tyred wheels or conveyor belts that needed a
`soft' start to behave acceptably.
Simultaneously my life's occupation was to resuscitate an old
Jaguar XJ6 car, with....  a torque converter.
..
I never found out the difference between the torque converter and
a fluid coupling. No mechanic can tell me.
Is this another example of confusion created by PR peddling?
(Jags. have to have fancy torque converters, not grubby
industrial drives you get down coal mines).
..
Next post I'll winkle a PIC into, I promise

Best regards,   John
..
email from John Sanderson at
JS Controls, PO Box 1887, Boksburg 1460, Rep. South Africa
Manufacturer & purveyor of laboratory force testing apparatus
and related products and services.
Tel/fax: Johannesburg 893 4154    Cellphone 082 453 4815