1. A FLUID PRESSURE MOTOR MECHANISM COMPRISING A MOTOR HAVING A CASING AND A PRESURE RESPONSIVE UNIT FORMING THEREWITH A PRESSURE CHAMBER, A NORMALLY STATIONARY MANUALLY OPERABLE MEMBER MOVABLE TO ACTUATE SAID PRESSURE RESPONSIVE UNIT A VALVE MECHANISM CONTROLLING COMMUNICATION BETWEEN SAID PRESSURE CHAMBER AND A PRESSURE SOURCE AND HAVING AN OPERATING MEMBER, A LEVER MECHANISM NORMALLY ENGAGING SAID OPERATING MEMBER AND HAVING A NORMAL POSITION FROM WHICH IT IS MOVABLE TO MOVE SUCH MEMBER AND OPERATE SAID VALVE MECHANISM TO CONNECT SAID PRESSURE CHAMBER TO SAID SOURCE, SAID LEVER MECHANISM NORMALLY HAVING LOST MOTION CONNECTION WITH SAID MANUALLY OPERABLE MEMBER WITHIN THE LIMITS OF WHICH LOST MOTION SAID VALVE MECHANISM IS OPERABLE WITHOUT MOVING SAID MANUALLY OPERABLE MEMBER, AND MEANS AUTOMATICALLY OPERATIVE UPON A FAILURE OF PRESSURE IN SAID SOURCE FOR MOVING SAID LEVER TO A DIFFERENT NORMAL POSITION AND TAKING UP SAID LOST MOTION CONNECTION AND FOR ESTABLISH MECHANICAL CONNECTION BETWEEN SAID LEVER MECHANISM AND SAID MANUALLY OPERABLE MEMBER FOR ACTUATING THE LATTER WITHOUT MOVING SAID OPERATING MEMBER.