Motion converting mechanism

Claim 1

A LINEAR ACTUATOR COMPRISING (A) AN ELONGATED HOUSING HAVING A SPLINED EXTENSIBLE MEMBER SUPPORTED IN AT LEAST ONE CORRESPONDINGLY SPLINED END OF SAID HOUSING, SAID HOUSING AND MEMBER BEING ADAPTED TO BE CONNECTED IN A MECHANISM FOR MOVING A LOAD AND ALSO BEING SUBJECT TO THE REACTIVE FORCE OF THE LOAD SO MOVED, (B) A LOW-FRICTION LEAD SCREW CONNECTED BETWEEN SAID HOUSING AND MEMBER FOR EXTENDING AND RETRACTING SAID MEMBER RELATIVE TO SAID HOUSING, (C) FIRST BRAKE MEANS BETWEEN SAID SCREW AND SAID HOUSING FOR RESTRAINING ROTARY MOTION OF SAID SCREW IN RESPONSE TO TORSIONAL FORCES PRODUCED THROUGH SAID SCREW BY NORMAL REACTIVE AXIAL LOADS THEREON, (D) SECOND BRAKE MEANS BETWEEN SAIS SCREW AND SAID HOUSING FOR RESTRAINING ROTARY MOITION OF SAID SCREW IN RESPONSE TO AXIAL FORCES PRODUCED BY GREATER THAN NORMAL REACTIVE AXIAL LOADS, (E) SPRING MEANS COUPLED WITH SAID SECOND BRAKE MEANS FOR RELEASING THE SAME WHEN SAID AXIAL LOADS ARE SUBSTANTIALLY NORMAL, AND (F) MOTIVE MEANS COUPLED WITH SAID FIRST BRAKE MEANS FOR RELEASING THE SAME AND FOR ROTATING SAID SCREW RELATIVE TO SAID HOUSING WHEREBY TO EXTEND AND RETRACT SAID MEMBER RELATIVE TO SAID HOUSING.