Gordon

Claim 1

IN COMBINATION: A BRUSH HOLDER FOR A DYNAMOELECTRIC MACHINE HAVING MEANS FOR URGING A BRUSH INTO ELECTRICAL CONTACT WITH THE MACHINE''S COMMUTATOR, SAID MEANS BEING RESPONSIVE TO A HYDRAULIC RESERVOIR, AND A MASTER CYLINDER CONNECTED TO SAID HYDRAULIC RESERVOIR, SAID MASTER CYLINDER HAVING A RING AND A BASE WITH A DIAPHRAGM HELD THEREBETWEEN AT ITS PERIPHERY TO FORM A SUBASSEMBLY, SAID DIAPHRAGM FORMING A MASTER CYLINDER HYDRAULIC RESERVOIR WITH SAID BASE, SAID DIAPHRAGM HAVING A CIRCULAR ARCUATE GROOVE NEAR TO POINTS IMMEDIATELY ADJACENT TO WHERE SAID DIAPHRAGM IS HELD, A COVER ASSEMBLY ATTACHED TO SAID SUBASSEMBLY, SAID COVER ASSEMBLY BEING A COVER ASSEMBLED WITH A DIAPHRAGM LOADER PLATE BY A GUIDE STUD PROTRUDING THROUGH SAID COVER, A COMPRESSION SPRING INTERPOSED BETWEEN SAID LOADER PLATE AND SAID COVER, SAID GUIDE STUD HAVING MEANS FOR KEEPING SAID COMPRESSION SPRING COMPRESSED UNTIL IT IS DESIRED TO RELEASE SAID SPRING TO EXERT FORCE ON SAID DIAPHRAGM.