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runs through the system with no resistance, and the pump does not cause much drag on the motor. But it does have a VERY tight belt on it, so it does drag the motor a bit even when the fluid is bypassing the rack. The higher the rpms, the more drag it causes. An accessory pulley not hooked up will spin many times with just a flick with a finger, but tighten the belt on it and it requires alot more effort to spin it. Now factor in that it is pushing a thick gooey liquid around circulating through the entire system, the labyrinth maze of a valve in the steering column, and then back UP towards the sky against gravity to return to the reservoir. This makes even more drag. And it has to push the goo around even faster as rpms get higher. More drag. Now compare to an electronically controlled motor. It only pushes the fluid around just enough to trigger the oil pressure sensitive switch, not circulating very fast at all, and it stays at that speed the entire rpm range. Only when it senses resistance does it kick in. Its closer to having no pulley at all when power steering is not needed, which is most of the time. When it IS needed, then yea it will be slightly less effecient than a regular pump. It's not like you'll notice a power decrease while turning like torque steer with a FWD car or anything. I'm guessing the reason they are not commonly OEM is because they are more expensive and make a car more complex and are not as reliable (electric motors break often on cars like the power windows and power antennae are both broken on my daily driver, and about every other vehicle I've owned has either of those break).
random sig pic of the day:
TAMPA BAY - HOME OF THE STANLEY CUP
--.scubasteve.-- |
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