Device for the removable fastening to a floor of the underframe of a seat and its application especially to land-based motor vehicles

A device for removable fastening, to a floor, of an underframe (P) of a seat, said underframe being movable between first and second positions by tipping it upon a given direction (.DELTA.), said device comprising:

• a striker plate (10) which is associated with the floor (S) and which exhibits two opposed faces (101,102), for bearing and for locking, pierced through by an opening (11) with a free passage (111) bordered by a contact area (112) on the locking face (102);
• a casing (20) which includes a lock bolt (30) comprising a hollow long straight locking body (31) with a cylindrical guide cavity (310), which has an axis orthogonal to said direction (.DELTA.), and with a tip (311), and with at least one passage (312) pierced through said body (31) to emerge into the cavity (310), and with an open end (313),
• said lock bolt (30) further comprising at least one ball (32) housed in said at least one passage (312) so as to be retained therein so that it can move between a first position projecting partially outside the body (31) so as to be able to encounter the contact area (112) to lock the lock bolt (30) onto the striker plate (10) when the tip (311) thereof is engaged in the free passage (111), and a second position retracted inside the body (31) so as to separate itself from the contact area (112) so as to unlock the lock bolt (30) from the striker plate (10),
• said lock bolt (30) further comprising a needle (33), housed so that it can move in the cavity (310) between an active position in which it allows said at least one ball (32) to project and an inactive position in which it allows the ball (32) to retract, with a cylindrical shank (331), with an inside end potion (332) consisting of a cone frustum (3321) converging towards a pilot (3322) to cause the ball (32) to project or retract, and with an outside end portion (333):
• a control (40) borne by the casing (20) and connected by a link (41) to said outside end portion (333) so as to move the needle (33) in the body (31), wherein the control (40) comprises a lever (42) which has an operating hand grip (421) and an articulation (422) associated with the casing (20) to allow it to turn about an axis parallel to the given direction (.DELTA.) between an unlocked position and a locked position and which bears the link (41) so as to be able to move the needle (33) between the two positions thereof;
• and
• a safety feature (50) coupled to the lever (42) and intended to interact with the underframe (P) to prevent said underframe from being tipped into the first position thereof as long as the lock bolt (30) is not locked onto the striker plate (10).