Hi from Germany,
er bought a Windstar in 95.
The vehicle features six safety belts. As it turned out only now, neither
one of them works. Although they can be buckled properly and there is no
visible sign of any defect, they will not block and are thus not able to
hold back a person during a crash situation. As it is more than unlikely,
that all six belts suddenly break, I suspect, that there has been somme sort
of a manipulation by a preowner with the effect, to disable the safety
function of the belt. The mechanic found out, that once taken out of the car
and held in the hand, the safety-mechanism works properly and the rolling
off is blocked by sudden pulling. But as soon as it is put back into its
position in the car, the belt will fully roll off and not stop.Any idea for
us? Thank you so muchKarin
The technician is correct, the belts are working properly.
You are confusing the old 'window shade' type of belt, that would lock when
pulled rapidly. The modern belt does not operate that way. The latching is
accomplished by a 'pendulum effect' motion within the latching system.
There are several tests one can perform that will indicate the latching
mechanism is working properly. Tilt one of the seats, that can be moved
forward for egress, then rapidly push it backward. If it latches when, it
bounces forward again, it is working properly. Another is to notice if the
belt latches if you apply the brakes as you descend a steep grade. A third
is pull the belt out completely, when released it will lock at the point
where you stop the rewind
There are multiple type of mechanisms employed. Some cars even have
pretensioners that actually pull the belts tighter under certain
circumstances (some even employ explosive devices for this purpose -
but those use the air bag sensors to fire the pretensioners along with
the air bags). There were cars that electrically locked the belts (I
think this is out of favor now). There are cars that use pendulums to
lock the belts. There are cars that use centrifugal devices to lock
the belts. Just because some Nissans do it one way, doesn't imply that
a 1995 Windstar should react in the same manner.
You could use both a pendulum and a centrifugal mechanism, but I doubt
they would. Under hard braking both methods would react the same way.
However, if you are sitting still and just yank the belts out, the
centrifugal method should lock the belts, while the pendulum method
won't. If you have a car that electrically locks the belts no amount
of yanking on the belts while the car is parked should do anything.
The net is, you can't just decide the belts aren't working right
because they don't lock when you pull them out when the car is sitting
still. If you want to know if they are working, go out into an empty
lot, get up to about 30 mph and lock the brakes. The belts should lock
up no matter what design is employed.
Did you try doing a panic stop (in a safe location with no traffic
around)? I've had cars that don't appear to lock the belts but
actually work fine under extreme braking. There are a variety of
locking mechanisms employed. Some use a centrifugal device that locks
the belts when hey are pulled out rapidly. Others use a pendulum type
device that locks the belt when the vehicle decelerates rapidly. When
removed from the vehicle the later type of device could appear to lock
the belts merely because it is held at a slight angle (those moving
the pendulum to the locking position). Try locking the brakes and see
if the belts lock.
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