Retractor for seat belt provided with buffer means against webbing taking up force

A retractor for seat belt provided with buffer means against webbing taking-up force comprising:

• a webbing take-up shaft rotatably supported on a base member and biased in the webbing taking up direction;
• a ratchet wheel mounted on said take-up shaft for rotation therewith and having engagement surfaces oriented in the webbing taking up direction;
• a ratchet engageable with said ratchet wheel to prevent said take-up shaft from rotating in the webbing taking up direction and biased toward a position engaged with said ratchet wheel;
• and
• a cam plate rotatable together with said take-up shaft and said ratchet wheel through frictional engagement therewith;
• and
• said cam plate comprising a first guide portion generally extending in the circumferential direction through an angle of more than 360 degrees and so formed as to guide said ratchet from the engaged position with said ratchet wheel to a position out of engagement with said ratchet wheel with the movement of the webbing being pulled out;
• a second guide portion generally extending in the circumferential direction a small distance beyond the beginning of said first guide portion and so formed as to guide said ratchet to a disengaged position immediately before the engaged position while keeping said ratchet out of engagement with said ratchet wheel with the movement of the webbing being taken up and then hold said ratchet in said disengaged position;
• and a third guide portion extending from the end of said second guide portion to the beginning of said first guide portion and so formed as to guide said ratchet from said held position to said engaged position with the movement of the webbing being pulled out.