Subject: Compressor Motor: HP v.s. Amps?
From: "Bob Swinney"
Date: 04/10/03 02:58 GMT Daylight Time
Message-id: vPpfb.489338$Oz4.334706@rwcrnsc54

"Richard J Kinch" wrote in message
...
Bob Swinney writes:

Torque is the capacity of an engine to do work ...

This, and many of your other comments here elided, are quite wrong.


So, Richard - we would like to hear your definition of torque. And could
you elucidate a bit on the many "elided" comments? Please, give us your
"take" on the correct facts.

Torque bears no relation to any capacity to do work. Although the two
quantities are expressed in the same units of force and distance, torque is a
vector quantity and work is scalar one. Torque merely defines an instantaneous
twisting force about an axis. It could be expressed as a capacity to overcome a
given load applied to that axis but not to do a given amount of work. We need
to also know speed to calculate that and thus horsepower is what defines
capacity to do work.

Inherent in the use of the word "capacity" is a time element. Any engine could
theoretically do any amount of work if left running for long enough. The use of
the term capacity without recognising the inherent time element makes the term
meaningless.

For example, the question "can an engine producing X amount of torque lift
those bricks to the top of that building?" is meaningless. Appropriately geared
any engine could do that but only the horsepower defines how fast it could do
it.

All torque therefore tells one is the shaft speed at which an engine produces a
given amount of horsepower and the load the engine can overcome at that shaft
speed without further gearing.


Dave Baker - Puma Race Engines (www.pumaracing.co.uk)
I'm not at all sure why women like men. We're argumentative, childish,
unsociable and extremely unappealing naked. I'm quite grateful they do though.