This is a general question about how to choose vacuum cleaner suction by
the specifications (specifically by amperage).
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At a garage sale, I picked up three vacuum cleaners for almost nothing
(because my fourth vacuum cleaner isn't all that great on carpets) and
three of the four work fine (the Dirt Devil has a broken belt & roller).

The amperage of the four vacuum cleaners is:
1. Dirt Devil 12.0 amps (no bags needed)
2. Eureka Express 11.5 amps (requires bags)
3. Eureka Rally 10.0 amps (requires bags)
4. Porter Cable wet/dry 4 gallon @ 8.0 amps (I bought this from Costco)

I realize the "amps" turn the motor, where we can presume that the more
amps, the more "power" - but what is the primary determinant of suction?

Is it the amperage?
Is it the geometry of the passages?
Is it the design of the motor vanes?

My main question is whether the suction is "mainly" a question of amperage?

My secondary question is what is a good "test" of the suction, bearing in
mind that I've already done a hand test, where they "seem" to be about
equal in suction (give or take a bit in about the order of amperage).

What vacuum cleaner suction wisdom can you impart upon me?
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