1944 Quincy 230-10 unloader problem

I have had this Quincy 230-10 for about 15 years and it has always given me good service but has developed a problem of tripping the breaker if pressure is in the tank over 80 psi. I started looking into why, found out it is a Quincy and searched and found lots of information that just didn't lead to why other than the unloaders are not functioning. The hydraulic pilot valve isn't hooked up to the tank and when I did attach it, the unloaders activate and no pressure is built. I have removed the valve and cleaned and made sure it moves freely but still it flows air at all times instead of cutting off so the unloaders allow pressure to build. The pin, that comes from inside the crankcase, and touches the pilot valve moves in and out freely. Looking in what seems to be the right manual it shows counter weights that operate this. Is there something else I should check or do before disassembling the compressor to get to the weights? I would be very grateful for any information.

If you can't fix the hydraulic unloader you could switch to a different type. My setup has a check valve between the compressor and the tank. A small 1/4 line comes from the compressor discharge line before the check valve and goes to a square D pressure switch that has the unloader built into it. When the compressor cycles off the unloader relieves pressure in the discharge line so that the compressor starts unloaded on the next cycle. Very simple and works well.

Once again. Quincy has a ton of service centers. Find yours. Call the service manager.

metalmagpie

deltap said:

If you can't fix the hydraulic unloader you could switch to a different type. My setup has a check valve between the compressor and the tank. A small 1/4 line comes from the compressor discharge line before the check valve and goes to a square D pressure switch that has the unloader built into it. When the compressor cycles off the unloader relieves pressure in the discharge line so that the compressor starts unloaded on the next cycle. Very simple and works well.

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That's a very genius idea and I wish I had thought of it sooner. It's also the most economical idea. I think I'm going to take your advice and skip the solenoid valve.