Experiments with the GM Power Pack Vacuum Compressor

[davepl]

As you may know, for trucks that wanted an air-powered option but that didn't have compressed air onboard like a Medium Duty might, you could add the GM Power Pack.

It seems to come in two flavors - one for the PleasureLift shocks and the other for horns. The latter includes a reservoir, the former does not. The former includes a gauge and a regulator, which the latter does not.

I was curious as to whether a single vacuum compressor could fill an air horn reservoir AND be used for the air shocks. I was worried that if the supply (pre-regulator) side of the air system were bled down (by hitting the horn, for example) tha the shocks might collapse.

So, I hooked up an electric vacuum pump to the vacuum-powered compressor so that I had it running, then I hooked it up to the regulator, and then to the shocks on the bench.

First off the regulator is WEIRD. You don't dial in a pressure, you center the knob to unlock it, then pull it out. Wait till your desired pressure on the gauge, then press in and turn to latch it. I had to read the 45 year old instructions for that one! Press the center of the button to bleed pressure off.

Once I had 95psi in the shocks as a test I removed the feed line to the regulator and it held the 95psi. So I can't prove it and don't suggest you rely on it by my experiments so far indicate that if, for example, the horns went off and the supply side of the air system dropped suddenly in pressure the post-regulator shocks don't seem affected.

Hope this helps someone one day! My memory is short so when I come back in 2 years asking about this thing, please point me back at my own post, it wouldn't be the first time :-)

Here's a picture of the vacuum pump powering the vacuum compressor connected to the PleasureLift regulator connected to an air shock, which is how I tested it all out.

[davepl]

I'm kind of disappointed, I thought people would be more interested in these old options and how they work and how they can be set up. I'm was never one to take my ball and go home, but I'm starting to understand the feeling :-)

Just for that, no magic video showing how the iPhone compass can correct the GM compass. My wife didn't believe me until I showed her, so I took a video. Without it my "Accurate Road Compass" was off by about 45 degrees from North.

[racerop]

Sorry Dave, But I Sometimes Don't Get To Read Post Between 8Pm AndEarly Afternoon. With That Said, I Am On My Phone And Takes Me Forever To Type With One Thumb. I Really Like And Appreciate The Time And Thought On The Vacuum Air Pump Information
On The Subject Of The Magnetic Compass. I Have Noticed The Deviation Near Large Metal Objects. I Hope What You Have On Your I Phone Can Be Duplicated On A Droid Based phone

[davepl]

Originally Posted by racerop

S
On The Subject Of The Magnetic Compass. I Have Noticed The Deviation Near Large Metal Objects. I Hope What You Have On Your I Phone Can Be Duplicated On A Droid Based phone

Yup :-) The compass is off by about 45 degrees but if you stick the metal iPhone up against it it goes directly to North. So it'll work with Android. And maybe old Commodore calculators too!

[racerop]

Cool! Good Info!
Thank You Davepl

I Have One Of Those Vacuum Pumps For An Air Horn And Was Thinking Of Regulation It For Something Else.
What Pressure Comes Out Of The Pump?

[davepl]

Originally Posted by racerop

Cool! Good Info!
Thank You Davepl

I Have One Of Those Vacuum Pumps For An Air Horn And Was Thinking Of Regulation It For Something Else.
What Pressure Comes Out Of The Pump?

If you let the gauge "run away" and max out, it goes past 125 and probably to what I'd guess is 150. Now it's a tiny 1/8" hose, so no volume to speak of, but if you had a reservoir it should work nicely.

I hope to integrate it with air horns and the shocks. Picked up some NOS Hadley/GMC Town & Country horns today, but they're the pull-chain type! Need a solenoid valve, tank, and all of that, so maybe time for a modern setup? But then that defeats the purpose of my ancient air.

I'm also tempted to toss the Vacuum gauge I have and replace it with an Air gauge, since (even without air brakes) that's probably more useful.

[hdff]

I would like to see and hear more about these air horns, I didn't know it was an option..

[davepl]

Originally Posted by hdff

I would like to see and hear more about these air horns, I didn't know it was an option..

I'll stick them in their own thread with photos...