Rail threader

Claim 1

A RAIL TREADER COMPRISING AN ARTICULATED, OPEN GENERALLY RECTANGULAR, FRAME-LIKE STRUCTURE THROUGH WHICH RAILS ARE ADAPTED SUCCESSIVELY TO PASS DURING MOVEMENT OF THE THREADER ALONG A ROADBED, SAID STRUCTURE INCLUDING A FIXED, GENERALLY C-SHAPED SUPPORT INCLUDING UPPER AND LOWER FIXED HORIZONTAL TRANSVERSE FRAME SECTIONS AND AN INTERCONNECTING FIXED VERTICAL FRAME SIDE SECTION, A MOV ABLE FRAME GATE SECTION PIVOTALLY CONNECTED AT ONE END TO THE DISTAL END OF THE LOWER TRANSVERSE FRAME SECTION FOR MOVEMENT BETWEEN A VERTICAL CLOSED POSITION WHEREIN ITS OTHER FREE END ENGAGES THE DISTAL END OF THE UPPER TRANSVERSE FRAME SECTION, AND AN INCLINED OPEN POSITION FOR ADMISSION OF THE RAILS SIDEWAYS INTO THE STRUCTURE, A PAIR OF LOWER ANTIFRICTION CONFINING ROLLERS SUPPORTED ON SAID LOWER TRANSVERSE FRAME SECTION FOR ROTATION ABOUT RESPECTIVE HORIZONTAL AXES AND ADAPTED TO UNDERLIE AND CONTACT THE BASES OF THE RAILS PAND THUS SUPPORT THE RAILS, A COMPOSITE UPPER ROLLER INCLUDING TWO NORMALLY COAXIAL ROLLER SECTIONS, ONE OF SAID ROLLER SECTIONS BEING ROTATABLY MOUNTED ON SAID FIXED FRAME SIDE SECTION NEAR THE UPPER END THEREOF AND THE OTHER ROLLER SECTION BEING ROTATABLY MOUNTED ON SAID GATE SECTIONS NEAR THE FREE END THEREOF, SAID ROLLER SECTIONS, WHEN THE FRAME GATE SECTION NEAR THE FREE END THEREOF IS IN ITS CLOSED POSITION, BEING INDEPENDENTLY ROTATABLE ABOUT COMMON AXES SPACED UPWARDLY FROM AND PARALLEL TO THE AXES OF ROTATION OF THE LOWER ROLLERS, SAID OTHER ROLLER SECTION BEING MOVABLE TOWARD AND AWAY FROM THE ONE ROLLER SECTION DURING CLOSING AND OPENING MOVEMENTS OF SAID FRAME GATE SECTION RESPECTIVELY, AND MEANS FOR INDIVIDUALLY EFFECTING VERTICAL ADJUSTMENT OF SAID ROLLER SECTIONS.