Trouble repairing air compressor

I was hoping that someone in this newsgroup might be able to help with this problem. I recently inherited an old Sears 1hp air compressor from the

1970's -- (model 160.171140). It wasn't in great shape but since I don't have one, I thought it would be great to fix up for the shop (this was back when Sears/Craftsman made decent tools right?). Anyway, I ordered the replacement parts from Sears at greatly inflated prices and they arrived today. They are not identical to the ones that were originally on the compressor, not that I expected them to. Most of the pieces worked out ok--the check valve was identical, gaskets fit great, shut off and safety valve is different but checks out (actually made of brass instead of the original plastic!) but the pressure switch is giving me some trouble...

It is a Square D Pumptrol Pressure Switch (I have the model and specs if that will help) and on the underside of the swich is attached a valve with four threaded holes in it. The one on the bottom is where it attaches to the shut off/safety valve, but I don't know about the other three? They are all connected so the tank wont hold any air. Can I get some covers or plugs to fill them all? On the old switch, there was a guage that showed the psi in the tank but this new one does not. Should there be another valve or guage threaded into the pressure switch? I'm a bit worried that if I simply plug those holes, the motor won't know when to shut off? Is that how it works?

I would really appreciate any help you could give me on this problem. I dread having to call sears for assistance since I don't really have half a day to wait on the tele just to talk to someone who has no idea what they're talking about so they can tell me that I need to schedule a service call!!

Thanks Jimmy

Reply to
Jimmy
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Reply to
Grant Erwin

The Pumptrol is a pressure switch, right? with wires coming out of it, right? If you connect this so it shuts off the motor when it snaps, then it should not hurt to plug all those holes. Besides, you are going to be standing there watching it run, the first time you plug it in. If it doesn't shut off when it should, you shut it off.

Reply to
Leo Lichtman

Try google. Enter the name and model number. I just googled "square d pumptrol" and one of the first hits was a page from a Square D website. Betcha find there what you want. You could even try calling them. ERS

Reply to
Eric R Snow

The tank is one-way-or-the-other connected to:

- the compressor (duh), through a one-way check valve,

- the outlet (duh again),

- the pressure switch,

- a pressure relief valve (the safety valve),

- a pressure gauge.

My compressor has a "christmas tree" fitting that all of these connect to. I'm thinking that your 4-way is similar. Maybe:

gauge | compressor - (switch) - outlet | tank

Bob

Reply to
Bob Engelhardt

The holes you describe sound as though they're provided as extra accessory ports, in that the switch assembly was probably made as a universal replacement part.

So it would just be a multi-tap manifold for a tank pressure gage, a tank pressure air outlet, a port for attaching a regulator, a hose quick disconnect, and any other connections you might need to make to suit your needs. You can most likely find 1/8" or 1/4" pipe plugs at most hardware places, for any of them that you don't use. The only other material you should need will be thread sealant.

WB .............

Reply to
Wild Bill

Go ahead and plug the holes you are not using on that main "cross" casting. They provide the other holes so you don't need more plumbing pieces to build the compressor - hang a pressure gauge off one hole, relief valve off a second, and the regulator and output QC chuck on the third.... Probably 1/4" NPT pipe threads.

As long as the diaphragm is getting tank pressure through one of the big holes, it will shut off.

There may be a smaller fitting on the bottom for an unloader valve, usually a schrader valve that opens when the pressure switch turns off, with a small fitting for 1/8" copper or nylon tubing. You connect that to a tee fitting on the compressor output line, before the check valve going into the storage tank.

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Reply to
Bruce L. Bergman

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