Am I missing something? I can understand that if you have the ability to switch-off an electric PS pump then savings will be made. But if it is running all the time, surely it will be less efficient than a belt-driven pump?
After all - you are first having to use the alternator to convert mechanical energy into electrical energy then convert electrical energy back into mechanical!
On my car, steering is immensely heavy when the hydraulic pump is not running - so if I had, and used, an electrical pump only at very low speeds, I would be in a situation which could be unsafe if I need to suddenly make big steering movements when the pump is not running...
An electrically powered steering column would seem to offer a much better solution - although the conversion could be a bit daunting for most...?
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