Torsion pre-load means

Claim 1

IN A RETRACTOR MECHANISM FOR ROLLING UP A SECTION OF FLAT BELT INCLUDING A REEL ADAPTED FOR CONNECTION TO A BIGHT PORTION OF SAID BELT, A REACTION MEMBER MOUNTED FOR ROTATION WITH RESPECT TO SAID REEL HAVING A PORTION THEREOF SPACED FROM THE AXIS OF SAID REEL ADAPTED TO BEAR ON SAID BELT, AND A TORSION SPRING HAVING ONE END THEREOF ANCHORED TO SAID REEL AND HAVING THE OTHER END THEREOF ADAPTED FOR CONNECTION TO SAID REACTION MEMBER, THE IMPROVEMENT COMPRISING: DRIVE MEANS CONNECTED BETWEEN SAID REACTION MEMBER AND SAID OTHER END OF SAID SPRING, SAID DRIVE MEANS BEING PROVIDED WITH A CAM SURFACE AND A STOP SURFACE; AND CLAMP MEANS DISPOSED ABOUT SAID REEL AND FASTENED AGAINST RELATIVE ROTATION WITH RESPECT THERETO, SAID CLAMP MEANS INCLUDING A STOP ELEMENT HAVING SLIDING ENGAGEMENT WITH SAID CAM SURFACE PERMITTING WINDING OF SAID SPRING IN ONE DIRECTION, SAID STOP ELEMENT BEING ENGAGEABLE WITH SAID STOP SURFACE IN THE OTHER DIRECTION PREVENTING UNWINDING OF SAID SPRING.