Need a Quiet 12v Air compressor

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Bill Shields
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Re: Need a Quiet 12v Air compressor

Post by Bill Shields » Tue Apr 06, 2021 6:43 am

Steam driven one lungers generally do not provide enough air.

They look nice as functional accessories but fall short on practicality.

Vacuum brakes work well. After all British railways used them for decades
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Glenn Brooks
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Re: Need a Quiet 12v Air compressor

Post by Glenn Brooks » Tue Apr 06, 2021 9:43 pm

So I was thinking of possibly making an axle driven pump, with a fairly large bore 2 or 3” diameter, driving it as low speed, as the loco moves. Maybe 300-500 rpm. I could possibly hook it up to the jackshaft. Haven’t made pumps before, but my steamer has a small simplex pump for air brakes, which seems fairly rudimentary. Of course the air brakes have never really worked properly, so maybe not the best example to think about. Worth experimenting, depending on how the OTC stuff works out...

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Re: Need a Quiet 12v Air compressor

Post by Bill Shields » Tue Apr 06, 2021 10:12 pm

Unless you are sitting on it...Will stall the axle...and may will anyway unless direct connected to a loco driver.

3" diameter piston at 100 psi will consume a large % of the output of your loco... if not all of it

Think about the size of your steam piston driving the loco..and the ACTUAL PRESSURE on it. Which is rarely = boiler pressure.

There is a reason these compressors have small pistons moving at high rpm.

Dave Sclavi has a really nice working air brake setuo... but to be reliable requires one of these viair pumps (or similar)....because if the reservoirs are not charged then the brakes are on.. just like the Westinghouse system.

IIRC his is on a bungee cord suspension inside of an insulated car ...and even then there is no question as to what is going on....but it works well.

Another idea I have chewed on is a car full of 2500 psi paint ball bottles....or one large bottle 8" diameter x 20" long....which can be had for less than the price of an air compressor

Charge them up and given enough of them you would be good for the day. Sure.. it costs a few $$ to recharge..but in the end maybe worth it.
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Re: Need a Quiet 12v Air compressor

Post by Berkman » Wed Apr 07, 2021 9:46 am

Don't over think it, just do what 95% of others do with airbrakes and buy a viair or similar small compressor and mount it in the car. It will work fine etc, if you ever want to add a steam pump etc you can, but that will get you a working and reliable brake system quickly

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Re: Need a Quiet 12v Air compressor

Post by Glenn Brooks » Wed Apr 07, 2021 1:39 pm

Hi guys, didn’t mean to imply I was thinking of an actual steam pump. Just the type of small axle driven air pump commonly found on live steamers - simple two stroke, ram type, slow rpm; in this case possibly driven off the jack shaft. Basically a miniature bicycle pump running off a cam shaft. Something like that.... but just something to think about at this point.

I plan on visiting our local DIY hardware store and see if I can talk someone on the floor into plugging one or two of these OTC pumps in and running them for a sound test.

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Re: Need a Quiet 12v Air compressor

Post by Bill Shields » Wed Apr 07, 2021 3:05 pm

stop and think about how many strokes it will take a pump of that type to make 100 psi in the volume of your intended reservoir..

and how will you fill the reservoir when the train / loco is not moving if the only compressor you have is wheel driven?

it is the old conundrum:

you need to move to make air to stop the train => but you do not want to move (or cannot move) until you have air to stop the train...

we have an OLD grain truck on the farm that has compressed air brakes...once you start the engine, you sit and wait until the compressor charges the reservoir to a certain pressure -> or you cannot stop the truck. It is not like today's brakes where they are spring on and AIR OFF -> they are air on and spring off....which I am certain seemed like a good idea to someone at the time...

loco axle feed water pumps have the same problem...if you are sitting, stuck in traffic, boiling water...you need another source of water (even if it is a hand pump)...
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Re: Need a Quiet 12v Air compressor

Post by rkcarguy » Thu Apr 08, 2021 1:32 pm

I was going to post what bill did. Spring on, air off brakes will provide the element of safety should you run out of air. But if you are relying on axle rotation to make air, well then you aren't going anywhere lol.
Bill, our old city busses were like that, scary. There was a series of stops that were closer together right at the end of the route that used too much air, so the driver would stop and meander around my dads store for 5 mins while the air built up.

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Re: Need a Quiet 12v Air compressor

Post by Berkman » Fri Apr 09, 2021 1:08 pm

If you want to use commercially available brakes from titan trains, tom b etc, just use a normal straight air system with clippard parts. It will be very reliable, easy to fix if needed, somewhat interchangeable with other trains and use off the shelf parts.

Don't over think it. you're making this way harder than it needs to be.

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Re: Need a Quiet 12v Air compressor

Post by Pontiacguy1 » Fri Apr 09, 2021 1:23 pm

Trying to find a "Quiet 12v Air compressor" is like saying I need a fuel efficient 3/4 ton truck. Some are more efficient than others, but none of them are ever going to be considered gas sippers, and the ones that are the most fuel efficient are also usually the most expensive and/or complex. Ditto your air compressor. Some are quieter than others, but they all make noise. You can make it less noisy, but it will probably always be audible when you are within 20 feet of the train.

I'd go for reliability and simplicity first. Once you get it up and running and are satisfied with how it operates, THEN go back and try to add some baffling, sound deadening, isolation pads, enclosures, etc... to make it quieter.

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Re: Need a Quiet 12v Air compressor

Post by Bill Shields » Fri Apr 09, 2021 7:17 pm

Like military intelligence or honest politicians?
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Re: Need a Quiet 12v Air compressor

Post by dnevil » Sun Apr 18, 2021 9:09 am

How about the air compressor from a Lincoln Town Car. They used it to inflate the ride cushion bladders. Very quiet. I found one used on eBay.
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Re: Need a Quiet 12v Air compressor

Post by Harold_V » Sun Apr 18, 2021 3:02 pm

dnevil wrote:
Sun Apr 18, 2021 9:09 am
How about the air compressor from a Lincoln Town Car. They used it to inflate the ride cushion bladders. Very quiet. I found one used on eBay.
Do you happen to know the maximum pressure it can develop?

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