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.