Re: [ihc] Air Brake Systems

[bearbvd@xxxxxxxxxxxxxx (Greg Hermann)]

At 1:14 PM 4/28/04, Tom Mandera wrote:
>Mac McMuffin wrote:
>
>> for all the air brake systems i'm familiar with, pressure in the air system
>> is regulated by an in-line pressure-activated mechanical governor and
>> constant-duty compressor.  when the system pressure falls below 95psi, the
>> governor cuts in and the compressor feeds more pressure to the system.  the
>
>That's pretty much what I figured.
>
>They're "constant duty" but will "vent" the air pressure (thus making
>"no" pressure against the compressor) except when needed.

AGAIN---they don't VENT compressed air, they hold the intake valves open to
'unload' the compressor. No check valve needed in the air line, the exhaust
valves in the compressor do that job.

Greg
>
>By not working against a pressurized vessel, it should make the air pump
>run cooler when not actively pressurizing things.
>
>I bring this up, partly because I bought a used SpeedAire compressor a
>few weeks back.  2hp pump, with a 3hp 220V (15amp) electric motor.  I
>paid $75, and for the money, the electric motor was a good investment
>even if I junk the rest.
>
>But I also have a Honda gasoline engine lying around from a generator
>someone parted out.
>
>I have friends that bring generators and 110V air compressors to races.
>  The gas generator makes electricity that powers the air compressor
>that makes compressed air.
>
>I was thinking I could just run the compressor pump off the gasoline
>engine directly and avoid all of the energy loss by converting gas to
>recip motion / heat energy to electricity to an electric motor to an air
>compressor.
>
>I just wasn't sure how I would "regulate" the output of the "always
>turning" compressor pump when coupled to a gasoline engine.
>
>One idea that might work, would be a one-way check valve into the tank,
>but between the valve and the compressor output, install a "T", with an
>electrically controlled air solenoid actuated by a typical pressure
>switch on the tank.
>
>This would let the compressor pump vent to atmosphere except when the
>switch indicated the tank needed more air.
>
>But where to get the electricity for the switch and solenoid?  How about
>adding a regular 12V alternator to the mix.  Bonus, it can charge the
>battery on the trailer for the trailer winch.
>
>Heck, get a big enough power inverter and add that into the mix, too..
>
>Meanwhile, the 3hp electric motor from the original air compressor can
>be used to run a PTO hydraulic pump feeding a tie-rod ram to operate my
>JD2 tubing bender. :D
>
>-Tom