Fluid pressure actuated servo-motor

Claim 1

IN COMBINATION WITH A PARKING BRAKE ACTUATOR FOR VEHICLE PARKING BRAKES HAVING A LEVER MOUNTED ON A SUPPORT ADAPTED TO BE CONNECTED WITH THE PARKING BRAKES AND A MEANS COOPERATING WITH THE LEVER FOR RETAINING THE LEVER IN BRAKE SETTING POSITIONS, RELEASE MEANS FOR THE LEVER RETAINING MEANS INCLUDING A RELEASE ELEMENT, A PAIR OF CUP-SHAPED MEMBERS OF SHEET METAL HAVING CYLINDRICAL WALL PORTIONS IN SLIDABLE TELESCOPING RELATION, MOBILE VISCOUS MATERIAL CONTAINED BETWEEN THE CYLINDRICAL PORTIONS PROVIDING A PRESSURE RESISTANT SEAL, ONE OF SAID MEMBERS BEING ANCHORED TO THE SUPPORT, EACH OF SAID MEMBERS HAVING ONE END WALL WITH THE OPEN ENDS OF THE MEMBERS IN ADJACENT RELATION, ONE OF SAID MEMBERS HAVING PASSAGE MEANS FOR CONNECTION WITH A SOURCE OF SUBATMOSPHERIC PRESSURE FOR REDUCING THE PRESSURE IN THE REGION BETWEEN THE END WALLS TO EFFECT SLIDABLE MOVEMENT OF ONE MEMBER RELATIVE TO THE ANCHORED MEMBER, AND MEANS CONNECTING THE SLIDABLE MEMBER WITH THE RELEASE ELEMENT OF CONTROLLING SAID RELEASE MEANS.