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Seat Belt Systems: Testing and Inspection



Occupant Restraint System Inspection and Verification
1. Verify the customer concern by operating the safety belt.
2. Visually inspect for obvious signs of mechanical and electrical damage.

Mechanical Electrical
Loose webbing
Warning indicator bulb
Damaged/frayed webbing
Buckle
Safety belt retractor and tongue assembly
-
Retractor
-
Buckle

3. If the fault is not visually evident determine the symptom(s) and proceed to the Symptom Chart.

Condition(s):

Normal Mode - Occupant Restraint System Inoperative
Possible Source(s):
- Broken tooth on retractor sensor gear.
- Loose webbing.
Action(s) to take:
- REFER to the Functional Test in this section.
Automatic Locking Retraction System (ALR) Inoperative.
Possible Source(s):
- Broken tooth on retractor sensor gear.
- Loose webbing.
Action(s) to take:
- REFER to the Functional Test in this section.

Poor Retraction


(!) WARNING:
IN THE EVENT OF AN ACCIDENT IN WHICH THE AIR BAGS HAVE BEEN DEPLOYED, ALL SAFETY BELTS THAT WERE IN USE AT THE TIME OF THE ACCIDENT MUST BE REMOVED AND NEW SAFETY BELTS MUST BE INSTALLED. FAILURE TO FOLLOW THIS INSTRUCTION WILL RESULT IN PERSONAL INJURY AND COMPONENT FAILURE.


If a safety belt does not retract correctly, check that the anchor covers and trim bezels are correctly installed and not rubbing against the safety belt webbing. Where necessary, check that the safety belt webbing is not rubbing at one end of the retractor cover slot and, if so, correct by loosening the retaining bolt, aligning the retractor to centralize the safety belt webbing and retighten the bolt.

The S-Type is equipped with two front and three rear inertia reel safety belts. These safety belts are "dual sensitive" which means that they have:

A vehicle motion sensor, which lock the safety belt webbing under braking, cornering, on steep hills and in adverse camber conditions.

A webbing motion sensor, which locks when the safety belt webbing is quickly extracted.

Both systems should be fully operational and can be checked by the tests below:

Vehicle Motion Sensor Test
Either of the following two procedures may be used to check correct operation of the vehicle motion sensor. Both methods require two people but note that people of larger than normal should not be asked to conduct these tests. This is to avoid the possibility of a fully unrolled safety belt webbing being mistaken for a correctly locked safety belt retractor.

Test Method 1 (braking)


(!) WARNING:
IT IS IMPORTANT THAT DURING THIS TEST, THE WEARER ALLOWS THE SAFETY BELT TO PROVIDE THE RESTRAINT, THE WEARER SHOULD NOT ATTEMPT TO ANTICIPATE THE SUDDEN DECELERATION AND THE DRIVER SHOULD NOT BRACE THEMSELVES AGAINST THE STEERING WHEEL. HOWEVER, BOTH THE DRIVER AND THE PASSENGER MUST PREPARE THEMSELVES FOR THE POSSIBILITY THAT THE SAFETY BELT WILL NOT LOCK. THE PASSENGER SHOULD HOLD THEIR HANDS IN FRONT OF HIM, JUST CLEAR OF THE INSTRUMENT PANEL OR FRONT SEAT BACKREST. DEPENDING ON WHICH BELT IS BEING TESTED. FAILURE TO FOLLOW THESE PROCEDURES WILL RESULT IN PERSONAL INJURY.


Select for this test a quiet or private stretch of road. Make sure that the road is clear and that the full visibility is maintained at all times.

Both driver and passenger should adopt normal, comfortable seating position. Both occupants should wear the safety belts and the safety belt webbing must be correctly adjusted, with no slack.

Proceed at a speed of approximately 6 miles/hour (10 km/h). Do not exceed 6 miles/hour (10 km/h) for this test.

Apply the foot brake sharply to stop the vehicle. If the vehicle motion sensitive lock mechanism is operating correctly, the safety belt webbing will lock and restrain the wearer.

Conduct the test twice in each front and rear passenger seat position.

Any safety belt retractor which does not restrain the wearer during this test must not be reused. A NEW safety belt must be installed.

Test Method 2 (Turning circle)
This method requires a flat open area of private road, sufficient for the vehicle to be driven in a continuous circle on full lock.

The driver should wear the safety belt provided and the belt webbing must be correctly adjusted, with no slack.

The passenger should occupy a rear seat with the safety belt correctly adjusted.

Start the engine and, with the steering on full right-hand lock, drive the vehicle in a continuous circle at 10 miles/hour (16 km/h). Do not exceed 10 miles/hour (16 km/h).

When the speed is stable, the passenger should attempt to slowly extract the safety belt webbing from each safety belt retractor in turn. If the vehicle motion sensitive lock mechanism is operating correctly, it will not be possible to extract the webbing.

Any safety belt retractor from which it is possible to extract the webbing during this test must not be used. A NEW safety belt must be installed.

Safety Belt Webbing Sensor Test
With the vehicle stationary and on level ground take firm hold of the safety belt webbing (on the tongue side of the upper safety belt anchor) and pull out quickly. The retractor should lock within 0.25 metre (10 inches), preventing further webbing payout. Any safety belt retractor from which it is possible to extract further webbing must not be used. A new safety belt must be installed.

Component Test

Service installation of Safety belts
It is possible that the safety belt assemblies installed in service may have been damaged during handling or installation to the vehicle. The damage is contained within the inner workings of the retractor and is therefore, not visible. However, the damage usually causes the retractor to stick or jam. The damage can only occur before installation is completed and is usually in one of the following ways:

The safety belt webbing is allowed to retract onto the spindle until it jams the locking mechanism in a way that cannot occur when the safety belt is installed in the car. The safety belt webbing prevents the correct locking action and if the safety belt webbing is snatched or jerked out of the retractor, the loads are not taken on this high strength locking mechanism.

The webbing is snatch loaded by attempted fast extraction or manual testing with the safety belt held in the hand. This can result in deceleration which are much higher than those occurring in accident situations and there is a risk of damage to the mechanism.

When handling safety belt assemblies, adopt the following procedures:


(!) WARNING:
IF THE FOLLOWING PROCEDURES ARE NOT SUCCESSFUL, REJECT THE SAFETY BELT ASSEMBLY. DO NOT TRY TO JERK OR SNATCH THE WEBBING OUT OF THE RETRACTOR AS THIS MAY CAUSE DAMAGE. FAILURE TO FOLLOW THESE PROCEDURES COULD AND MAY CAUSE DAMAGE OR PERSONAL INJURY.


If the safety belt webbing retracts and will not extract under low webbing tension, install the retractor onto its mounting in the car, which will set it at its correct angle, and the safety belt webbing should extract easily.

If it does not, feed 5-10 mm (3/16 - 3/8 inch) more safety belt webbing onto the spindle (rotate the spindle using finger pressure if necessary) and the safety belt webbing should then extract.




















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