View Single Post
  #5   Report Post  
Dave Baker
 
Posts: n/a
Default Compressor Motor: HP v.s. Amps?

Subject: Compressor Motor: HP v.s. Amps?
From: "Bob Swinney"
Date: 03/10/03 15:10 GMT Daylight Time
Message-id: t

Chuck sez:
"...I thougth torque was the direct product of the motor's
hp. How does the amperage come into play? Can you have a "strong" or
"weak" 3/4 hp motor? What factors actually determine the torque? Or, am

I
looking at this equation in the wrong way?"


Torque is the capacity of an engine to do work whereas HP is the rate at
which an engine does work. [Torque, in foot-pounds = (Horsepower x 5252)
divided by RPM.] For instance, an engine doing 250 HP of work and turning
at 1200 RPM has torque of 1094 ft. lbs. Torque is the force causing a shaft
to turn, sometimes called "turning moment". Torque, discounting friction,
is the same in each moving member of any transmission link - this is true
because of the equation above. In a machine working at any given rate (HP),
torque is the same at each link in the machine from the output shaft through
the transmission and on to the wheels.


Of course it isn't. If that were the case there would be no point in having
gearboxes. Horsepower is the same at any point in a machine, apart from
frictional losses. Torque varies inversely with rpm as altered by gearing. The
whole point of a gearbox is to multiply torque.

RPM varies from link to link because
of diameter differences but torque is the same everywhere.


If that were true then horsepower would be being created from nowhere or
dissipated to nowhere at different points in the machine, in violation of
everything that physicists hold sacred.



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.