tested my air system today, woo hoo!

[bevans6]

You can tell I am terminally bored, it being a holiday up here I feel duty bound to not do any actual work.  I haven't fully tested the air system since I drove out there from Ontario last October so even though I haven't driven the bus anywhere I thought I would go through it.  I start with a DOT daily inspection.  Start the bus with the tanks all empty, watch the pressure start to rise, observe the low air alarm on and the buzzer sounding nice and loud.  Pressure is climbing nice and fast, after about 3 minutes it stalls at 60 psi as the PPV valve opens and starts to let air out into the accessory system.  Seconds later the high idle kicks in as air gets back to it.  Around 90 psi the low air alarm goes off and the generator starts to charge the batteries.  At 120 psi the governor kicks over and the air dryer purges while the compressor unloads.  With the engine still running I fan the brakes down to 70 psi, the low air alarm comes back on, then I time the compressor recovery time from 85 to 100 psi - 30 seconds which is normal for this bus.  Next I observe the air pressure with the engine off, less than 3 psi loss over 1 minute, then the same with the brakes applied.  Good to go.   Now I move the bus and test the brakes actually work, then I park the bus, apply the parking brake and check that it actually works.  That is the normal daily inspection that I do before I drive the bus, but next I want to test the air tanks, check valves, emergency brake tank and the pressure protection valve.  I'm starting with 120 psi on the gauge and the engine off.  In this case I have set the parking brake, since that was the last thing I tested as part of the daily inspection, but an option is to do this next series of steps with the parking brake off and the bus chocked.  Outside the bus I first drain the wet tank.  It should have little to no moisture or oil in it, and it doesn't, great given that I have a new compressor and I haven't driven the bus more than a mile in almost a year.  I check that the air pressure gauge on the dash still reads 120 psi - since my air pressure gauge reads the pressure in the dry/service tank, this tells me that the check valve between the wet tank and the dry tank is operating correctly.  Next I drain the accessory tank.  No moisture at all, which is good, and after it is down I can observe that the air pressure gauge is reading 60 psi - confirming that the pressure protection valve is operational and closing at 60 psi to save air in the dry tank.  Next I drain the dry tank, air pressure goes down to zero on the gauge.  Finally I drain the emergency parking tank.  It holding air pressure after all else is drained confirms that the check valve between it and the rest of the air system is functional.  As it drains and gets fairly low, I could check that the parking brake push-pull valve sets automatically at around 40 psi, but I already have the parking brakes on and I don't have an air pressure gauge set up to read that, so I don't bother with that test.

This process, along with checking the brakes physically before a long trip, checking stroke every once in a while, is how I check out my air system.  It took me about 20 minutes to do today.  Kind of fun until it started to rain, then I rushed....  

Sitting on the front porch in the screen room I built a few weeks ago, about 72 degrees, enjoying the bugs not being inside and the rain falling in the thunderstorm that is rolling past and frankly dreaming a bit about the bus trip I want to take in September...

Brian

[lostagain]

Sounds great Brian!

You need to go for a nice drive with it though. Before September...

JC