Seat belt retractor

A retractor for a vehicle safety restraint comprises: a spool, rotatably mounted in a frame, for storing seat belt webbing, a ratchet wheel rotatably mounted to rotate with the spool, a control member (4) mounted in the frame, a locking pawl (12) pivotally mounted in the frame to pivot into engagement with the ratchet wheel, a sensor (6) responsive to an emergency, a mechanism for coupling the control member (4) to the spool on activation of the sensor (6), a cam surface (14) and a cam follower (13) coupling the locking pawl (12) to the control member (4). The cam surface (14) has a discontinuity arranged so that the cam follower (13) loses contact with the cam at high speeds but stays in contact with the cam surface at low speeds. Preferably the discontinuity is a raised portion (16) providing a first ramp in one direction in one portion on one side of the discontinuity of the cam surface and a second ramp in a different direction in a second portion of the cam surface on the other side of the discontinuity.