oil safety switch

[ruffcab69]

lord help me,well here goes,i know it works off pressure,but is it the sum of oil pressure and crankcase pressure or the difference between them?

again thankyou for any help!

[-80guru]

difference

[lirunaway]

Yes

[ruffcab69]

thankyou guys!

[jogas]

IMHO,
Memorizing "what" something is will just about guarantee you'll be scratching your head later about the same thing.
Visualizing "what" is actually happening will guarantee you'll always remember.
An oil safety switch, or oil pressure switch is there to protect the compressor from low oil pressure, and the damage it causes to the crankshaft, rods, bearings, etc.,.
The compressor's oil pump is located on or inside the compressor, and draws oil from the compressor sump(like the oil pan in your cars engine). The sump is at suction pressure(actually just a little below to promote flow). Therefore, the oil pumps "base pressure" is suction(sump) pressure. The pump then draws oil from the sump, pressurizes it to supply the compressor with "pressurized oil".
Therefore, the best way to get a true oil pressure is to measure the "difference" between the sump pressure and the oil pump discharge pressure. You use suction(or sump) pressure because it is the base pressure the oil pump begins with on it's inlet.
Therefore, the oil pressiure switch monitors the difference between the suction pressure and oil pump discharge pressure.
jogas

[ruffcab69]

A Great answer, and a great way of thinking,i'm going to apply it,thankyou for your help!