Power Steering and Power Assisted Steering ?

The message from "Graham" contains these words:

Not that I'm aware of. In both systems some control remains if the power fails - though generally you'd have to have arms like a blacksmith to be able to park it.

Graham ( snipped-for-privacy@pztech.dynu.net) gurgled happily, sounding much like they were saying :

In a sense, he's right. However, in the real world, they mean the same thing - where you have power assisting the mechanical linkage to turn the wheels, as on 99.9% of cars with "power steering" - with either a mechanical hydraulic pump, an electric hydraulic pump or electric assistance.

There's been very few fully powered steering on normal production cars - the only one I can think of offhand is Citroen's DIRAVI, fitted to the SM, CX and some LHD V6 XMs, as well as to a few '70s Maseratis.

In that, the mechanical linkage is only there as an "oh, s*it!" fail-safe,

- when you have no hydraulic pressure, you have about 30deg of play in the steering. In normal use, you have system pressure (about 2500psi) doing ALL the work, including a powered return to centre - release the steering on full lock while the car's stationary, and watch the steering centre itself. It's physically impossible to turn the steering from the road wheels, as you're pushing against 2500psi of hydraulic pressure - and really funny to watch an MOT tester try...