Longitudinal locking mechanism for vehicle seat

A longitudinal locking mechanism for a vehicle seat, comprising:

• a tubular base member;
• a male lock means having an external threaded portion, said male lock means being so slidably accommodated in said tubular base member as to project therefrom and withdraw thereinto in a longitudinal direction thereof;
• a female lock means connected to said tubular base member, said female lock means having a bellmouthed split end portion in which a plurality of split sections are so defined as to be elastically warped outwardly and radially relative to a central axis of said female lock means, wherein inwardly threaded regions are defined in said plurality of split sections, respectively;
• a slide means which is so slidably attached about said female lock means as to be movable along a longitudinal direction thereof for warping said plurality of split sections of said female lock means in a direction towards and away from a central axis of said female lock means;
• an operation lever;
• and
• an actuation means operatively connected to said slide means and operation lever, said actuation means being operable via said operation lever to cause said slide means to be slid along said female lock means in the longitudinal direction thereof so as to forcibly warp said plurality of split sections of said female lock means inwardly towards said central axis of said female lock means to thereby bring said internally threaded regions of said plurality of split sections to a meshed engagement with a part of said externally threaded portion of said male lock means, so that said male lock means may be locked at a selected point relative to said female lock means and thus, a desired amount of projection of said male lock means may be adjusted from said tubular base member.