A delivery apparatus for delivering a prosthetic heart valve , comprising: an elongated, first component (304; 404) comprising an engagement portion (308; 408) having threads or grooves (314; 412) and a disengagement portion (320; 416) lacking the threads or grooves (314; 412); a travelling, second component (188; 150) coaxially disposed relative to the first elongated component (304; 404), the travelling component (188; 150) comprising threads or grooves (314; 412) configured to mate with the threads or grooves (314; 412) of the first elongated component (304; 404); and a biasing member (332; 426) located proximate the disengagement portion (320; 416) of the first elongated component (304; 404); wherein the first elongated component (304; 404) is configured to be rotatable relative to the traveling component (188; 150) such that rotation of the first elongated component (304; 404) causes the travelling component (188; 150) to move axially along the threads or grooves (314; 412) of the engagement portion (308; 408), the threads or grooves (314; 412) of the travelling component (188; 150) disengaging from the threads or grooves (314; 412) of the engagement portion (308; 408) upon movement of the travelling component (188; 150) into the disengagement portion (320; 416) of the first elongated component (304; 404), and the biasing member (332; 426) biasing the travelling component (188; 150) against the threads or grooves (314; 412) of the engagement portion (308; 408) such that the travelling component (188; 150) reengages the engagement portion (308; 408) when the rotational direction of the first elongated component (304; 404) is reversed. an elongated, first component (304; 404) comprising an engagement portion (308; 408) having threads or grooves (314; 412) and a disengagement portion (320; 416) lacking the threads or grooves (314; 412); a travelling, second component (188; 150) coaxially disposed relative to the first elongated component (304; 404), the travelling component (188; 150) comprising threads or grooves (314; 412) configured to mate with the threads or grooves (314; 412) of the first elongated component (304; 404); and a biasing member (332; 426) located proximate the disengagement portion (320; 416) of the first elongated component (304; 404); wherein the first elongated component (304; 404) is configured to be rotatable relative to the traveling component (188; 150) such that rotation of the first elongated component (304; 404) causes the travelling component (188; 150) to move axially along the threads or grooves (314; 412) of the engagement portion (308; 408), the threads or grooves (314; 412) of the travelling component (188; 150) disengaging from the threads or grooves (314; 412) of the engagement portion (308; 408) upon movement of the travelling component (188; 150) into the disengagement portion (320; 416) of the first elongated component (304; 404), and the biasing member (332; 426) biasing the travelling component (188; 150) against the threads or grooves (314; 412) of the engagement portion (308; 408) such that the travelling component (188; 150) reengages the engagement portion (308; 408) when the rotational direction of the first elongated component (304; 404) is reversed. <EOS>