MC5 8v71 compressor

[Dreadnought]

Now I'm full timing- the biggest difficulty for a tinkerer like me- is not having access to my tools and my old workshop :-(

I was thinking how nice it would be to have a compressor but was ruling it out due to space ( you really have to be quite ruthless sometimes) and my friend - really said a compressor would be very useful- to pump up the tyres, to respray ( I have plans to get my bus to the colour choice I want!) and for air wratchet tools).

Then I thought- why not use the compressor that's part of the engine? I realize that there would be some difficulty when working on the engine as you'd have to have it running ;-).

I know for respray- you need a good 5 cfm-9 cfm compressor to make any real progress.

Does anyone know the cfm rating of the compressor fitted to say, an MC5 or MC9? I know that my pressure relief goes off at about 125 psi.

[buswarrior]

Chart in this Bendix publication:

http://www.bendix.com/media/documents/products_1/compressorsgovernors_1/tf550750.pdf

a Tu Flow 550 displaces 13.2 cfm at 1250 rpm,
a Tu flow 750 displaces 16.5 at 1250 rpm

That will be compressor rpm...

Anyone would be mighty proud to have a shop compressor with those ratings!

Be careful where you tap in, the discharge muffler (drain daily valve)r down the back is a common place, but will feed oil and water into your air tools and make a proper mess of your paint gun, if you don't figure a work around to capture/empty that before and during your work.

Some airbrake trivia, that 1250 rpm rating is the sweet spot where the compressor is most efficient. Higher than that, it can't suck in as much air before the valves close... try to breath deeply and fast, doesn't work for a compressor either...!

Running the coach against the governor attempting to build air displays for all to hear that a busnut (and many a "professional" driver) doesn't know about pneumatics... a simple fast idle pumps the strongest.

happy coaching!
buswarrior

[Dreadnought]

Thank you sir - very useful information and a real exciting future possibility. Pleased I chose this over a schoolie now .

[Iceni John]

It could still be worth also having a small electric compressor connected to the accessories system.   If you just need a small amount of air to inflate tires (tyres?) it will be as good as the engine's compressor.   I have a Harbor Fright twin-tank 4-gallon oil-lubricated compressor that sits above the front axle between the frame rails, and it feeds through a water trap / filter before connecting to the accessories tank  -  I'm always amazed how much water this little filter pulls out of the air, even on days that are not humid.   I judiciously tweaked the compressor's regulator so it now cuts out at the same 120 PSI as my Bendix Tu-Flo 700.

After my fiasco earlier this year with the split hydraulic fan motor that necessitated me being towed back to the yard by a wrecker truck, I realized that every bus should have a way to easily air up its entire air system to release brakes when being towed.   I already had an Industrial-style male air connector on the end of my electric compressor's tank drain, but the tow truck only had an Automotive-style female coupler, so we had to make an adapter otherwise I wasn't going anywhere.   I now have made a simple Industrial to Automotive adapter for just such an eventuality.   I also encountered a problem back-feeding air from the accessories system back into the bus's brake system  -  there's a valve and male outlet on the wet tank to connect an air line to, but it requires serious spelunking under the bus to reach it.   I've now made a simple valve connection between the accessories and brake air systems so in an emergency I now just turn one valve to air up the entire bus.   Easy!

Along with the electric compressor I now have three air outlets around the bus, one on each side and one back by the engine, and this makes it easy to inflate tires or to use my air grease gun when lubing the million Zerks everywhere underneath.

John

[bevans6]

Compressor RPM is the same as engine RPM, it's driven off the cam on a MC-5.  If you take the feed from the auxiliary air tank under the driver's seat, it will be after the air dryer and will have good dry air.  But - many yards of thin tubing will affect air flow for painting or sandblasting.  Lots of truck wheels have been blasted and painted with an idling engine...