Air compressor switch adjustment

[Kristin]

Hi,

I just got an Ingersol Rand compressor from the "FREE" pile down the street, it?s obviously been neglected and abused but it does run. I am only going to use it occasionally for topping up the car tires and bike tires, perhaps a blow gun for cleaning stuff.

Like I said it is in rough condition, I have begun to adjust the pressure switch. (A)Big spring = cut out, (B)small spring = differential and it?s working OK, what is the third bleeder valve[C]? When the contacts open a lever depresses a small brass valve that bleeds air, this is connected to the manifold under the pressure switch. Should this bleed as soon as the limit is hit or delay until the lower or differential pressure is about to kick back in? It looks like either the valve can be raised/lowered by it?s mounting nuts and there is a plunger on the armature of the switch that screws up/down in a plastic thread. Photo here:

I still need to replace the power cord as the Bozo before me spliced on a two wire cord of too light a gauge wire. Should I carefully lubricate the pressure switch where it pivots or is it best left alone.

Thanks in advance for any input, and if anyone knows the make or model of this switch I would appreciate that as well, there is no dust cover so I don?t know who made the switch.

Kristin

[Kristin]

Staring at the pressure switch some more I see the spring I labled "B" does nothing. there is a screw post with a pin thru it on which rests a flat washer, a smaller washer then the spring, then a cup washer and the nut. the lever from the contacts is above the washers and never makes contact with the spring or other parts. If anyone has a similar switch and can take a picture and either post it or e-mail to kd006(at)yahoo.com I just may be able to figure this out.

Thanks Kristin

[Steve Barker LT]

That is called an "unloader" valve. It releases the pressure off the discharge line so the compressor can start back up easier.

[Richard J Kinch]

Could be an unloader, or an overpressure relief.