Oil deficiency indicator

Claim 1

IN AN OIL DEFICIENCY INDICATOR FOR A MACHINE TOOL, A BODY HAVING AN OIL RESERVOIR, AN INTERMITTENTLY OPERABLE OIL SOURCE INCLUDING A PUMP CONNECTED TO SAID RESERVOIR; A DELIVERY CHAMBER IN SAID BODY HAVING AN INLET COMMUNICATING WITH SAID RESERVOIR AND AN OUTLET; A CONDUIT BETWEEN SAID OUTLET AND A PART OF SAID MACHINE TOOL REQUIRING LUBRICATION; AN ELECTRICALLY INSULATED CHAMBER IN SAID BODY; A PAIR OF SPACED INSULATED ELECTRICAL CONTACTS AT ONE END OF SAID CONTROL CHAMBER AND FORMING A PART OF A NORMALLY OPEN ELECTRICAL CIRCUIT, INCLUDING A SIGNAL DEVICE; AN ELECTRICALLY CONDUCTIVE PISTON MOVABLY POSITIONED AND SEALED WITHIN SAID CONTROL CHAMBER AND SPACED FROM SAID CONTACTS; A FIRST PASSAGE COMMUNICATING BETWEEN SAID OUTLET AND THE SIDE OF SAID CONTROL CHAMBER ON THE OPPOSITE SIDE OF SAID PISTON FROM SAID CONTACTS; AN AIR PASSAGE IN SAID BODY COMMUNICATING WITH SAID CONTROL CHAMBER ON THE SAME SIDE OF SAID PISTON AS SAID CONTACTS; AND A SOURCE OF CONSTANT AIR PRESSURE CONNECTED TO SAID AIR PASSAGE YIELDABLY MAINTAINING SAID PISTON SPACED FROM SAID CONTACTS; ANY BLOCKING OF SAID CONDUIT TO SAID TOOL CUTTING OFF OR REDUCING FLOW OF LUBRICANT THERETO AND PROVIDING A FLOW OF OIL THROUGH SAID FIRST PASSAGE TO SAID CONTROL CHAMBER WITH SUFFICIENT PRESSURE BUILT UP FOR MOVING SAID PISTON AGAINST THE BIAS PRODUCED BY SAID SOURCE OF CONSTANT AIR PRESSURE, THEREBY CAUSING SAID PISTON TO BRIDGE SAID CONTACTS AND CLOSE SAID CIRCUIT.