Parking brake tank

[Sam 4106]

I am still wanting to tap into one of the bus air tanks on my MCI 8, for my 1" impact wrench. There is a plug in the parking brake tank that is large enough, so, is there any reason not to tap in there? I will use hydraulic hose to the tool compartment, below the front electrical compartment, on the drivers side, and put a ball valve between the hose and the quick connect air fitting. If there is a good reason not to do that, please tell me. As always, your thoughts are appreciated.

Thanks, Sam

[bevans6]

Pretty much the only reason not to do it has to do with failure mode characteristics.  Remember it's actually the emergency brake tank, even if it sometimes gets called the parking brake tank.  If everything works right, and you only use the outlet when the bus is parked, then it shouldn't matter.  If the connection, the hose, the whole attachment ever fails in any way that develops a leak while you are driving, the bus will lose air pressure, but in a very special way - you will lose your emergency brake system first, not last.  Just as a matter of engineering design philosophy that is the wrong thing to do.  

What I would do, having a very similar bus to you, is get another tank and install it either in the front spare tire bay if I didn't carry a spare tire, or in the bottom of the compartment under the driver, underneath the existing auxiliary tank, and plumb it be fed from the drain port of the auxiliary tank.  That is where I have my air take off plumbed, just no extra tank.  That way you get some air tank capacity to make the impact work better, and you preserve the design of the bus emergency brake system.  I would have to think it through, but tapping into the wet tank would probably also be acceptable it there was a ball valve directly on the output of the tank, before any hose.  The wet tank will recover the quickest if the engine is running since the feed to it via the air dryer is quite large, the feed forward from the dry tank to the parking/emergency tank and the auxiliary tank is quite small, and the wet tank is a decent size, looks like around 6 gallons at a guess.

Brian

[Don4107]

Set up your impact with a punk tank.  A small portable tank with a big short hose to give max volume to the impact.  Feed the tank from any air source.  Gives you full impact for a few seconds to do the big jobs.