PRE-TENSIONER SEAT BELT [TWO-STEP DEPLOYMENT CONTROL SYSTEM]
2016 – MX-5 – Restraints
PRE-TENSIONER SEAT BELT [TWO-STEP DEPLOYMENT CONTROL SYSTEM]
Purpose
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The pre-tensioner seat belt retracts and tightens the belt webbing (between buckle and pre-tensioner seat belt) against the occupant’s upper torso to hold the occupant firmly in the seat and protect the occupant during a collision.
Function
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The pre-tensioner seat belts operate (deploy) based on the operation signal from the SAS control module to instantly retract and tighten the belt webbing, restraining the driver and passenger.
Construction
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The pre-tensioner seat belt is located in the seat belt retractor of the seat belt.
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The pre-tensioner seat belts consist of the following parts shown in the figure:
Operation
Normal operation (pre-tensioner non-operation)
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The locking base of the pre-tensioner seat belt is separated from the ring gear.
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The locking base of the pre-tensioner seat belt rotates in conjunction with the withdrawl/retraction of the seat belt.
Pre-tensioner activation
1. The gas generator emits a spark (1) when a signal is received from the SAS control module, causing gas to form.
2. The ball in the cylinder is pressed (3) by the generated gas pressure (2) and the ring gear is removed (4) from its securement.
3. The ring gear which is removed from its securement is caught in (5) the locking base, and the force of the pressed ball is transmitted to the locking base.
4. The locking base rotates and the seat belt is retracted (6).
Fail-safe
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Not applicable