Abstract: A deceleration sensor for detecting a threshold level of deceleration indicative of a vehicle collision, comprising a pair of sensor masses in the form of pendulums, a spring-loaded firing pin, a pair of trigger levers which individually hold the firing pin in a dormant state as long as they are held by the sensor masses in their neutral states but can be individually disengaged from the sensor masses by the motion of the sensor masses as a result of detecting a deceleration level greater than the threshold level. Since the firing pin is released only when both the trigger levers are released from their neutral states, the reliability of the dormant state of the firing pin is assured. To the end of improving the reliability of the activation of the firing pin, the firing pin may be spring-loaded by a pair of springs in such a manner that either spring is sufficient for the activation of the firing pin.

Abstract: A deceleration sensor for detection for deceleration greater than a certain threshold level, comprising: a firing pin; a sensor mass which is guided for motion along a first direction in a casing and is urged by a first spring member along the first direction so as to oppose an inertia force that will be applied to the sensor mass as it experiences deceleration which is to be detected; a trigger arm which is pivoted at its base end and comprises a first free end which is urged by a second spring member into activating the firing pin and a second free end which is engaged with the sensor mass so as to oppose a rotational motion of the trigger arm under a biasing force of the second spring member; and a shoulder surface provided in the sensor mass for holding the trigger arm against the biasing force of the second spring member be being engaged with the trigger arm under a normal condition and releasing the trigger arm by being disengaged from the trigger arm when the sensor mass experiences acceleration greate

Abstract: A seat belt tightening device for removing slack in a seat belt when the seat belt is required to positively restrain a passenger, comprising clamp members for clamping a part of the seat belt paid out from a retractor device; a winding member for winding thereonto a portion of the seat belt that is located ahead of the part clamped by the clamp means by a rotary motion; and a drive source for causing a rotational motion of the winding member. The winding member may be either integral with one of the clamp members or separate from both of them.