The Murphy Builders Site

When facing the drive gear that drives a vacuum pump it turns counter
clockwise. Looked at another way, if I was holding the vacuum pump in my
hand with the splined shaft facing me it would be turning clockwise. Does
this mean that when ordering a vacuum pump I should order counter clockwise
or clockwise? I don't know what the convention is.

Mike
044SR




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I can't believe how hard it was to get the answer to my question about
vacuum pump direction of rotation. IAs at the airport couldn't help me. I
finally did get the answer from the second guy I talked to at RAPCO.
Somebody else on this list is bound to need the answer eventually. The hard
part is perspective. Read the description below carefully.

If you are looking at the gear that drives the pump, facing the gear with
the pump removed, it's rotation determines the direction of the pump you
should order. If the drive gear on the engine turns clockwise you need a
clockwise pump. Another way to look at it is if you are holding the pump in
your hand with the gear facing you, if it turns clockwise it is a
counter-clockwise pump. That's because the end with the gear is considered
the "back" of the pump and direction is defined while looking at the front.
Hold the pump in your hand with the gear facing away from you and the
direction of rotation identifies it as CW or CCW. Confused? You can always
buy the expensive SigmaTek pump that works either way.

Caveat: I won't really know if the guy at RAPCO was right until I get the
pump mounted and try it. He sounded confident so here's hoping.

Mike
044SR




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