Team-BHP - car door latch

I have always wondered why there are two positions in card door latches.

i.e., between fully closed and fully open, why there is a position which is not completely closed (the door ajar warning keeps beeping), but we still cannot open the door. any specific reason behind that?

hi vivek,

> i.e., between fully closed and fully open, why there is a position which is not > completely closed (the door ajar warning keeps beeping), but we still cannot > open the door. any specific reason behind that?

Safety?

At that position :
* The door position sensor is not sufficiently pressed by the door to stop the warnings
* The door is still held by the latch, but not completely. The hold is enough to maintain position - unless there is a strong shock / momentum which can pry the door open.

It is not intentional, but the door-ajar warning unit is designed to tell you that the door is not completely & well shut - though at first glance it appears to be closed.

Quote:

the door is not completely & well shut

I believ his question is why doesn't door close completly i.e. it should either close or should not why is there an intermediate position for lock?

If my understanding is correct then the reason I belive is that our latches have two stage lock mechanism. The door is half closed if only first stage of locking happens & fully when the 2nd stage locking is done.

The door ajar warning comes up when door is only locked at first stage.

if I find a good picture to explain I will post

Quote:

Originally Posted by condor (Post 914706)

* The door is still held by the latch, but not completely. The hold is enough to maintain position - unless there is a strong shock / momentum which can pry the door open.

the Q is why? why can't it just have two positions, open and closed? this intermediate position itself causes confusion many times in some cars. I had a case when while driving the door suddenly opened. the warning was only visual and for some reason I had overlooked it.

Excellent question vivekiny2k,

I think the cause of this is purely due to the mechanical functioning of the latch - and i guess things havent changed much since :
1. This is the cheapest/simplest locking mechanism to produce
2. None of the big manufacturers have innovated much in this area?

Some of the new luxo-barges eliminate this problem - they close the doors with the press of a button, or also, when you bring the door close to closing, it closes itself - you dont need to apply any force.

cya
R

hm, that makes me think, in cars like mustang where door is just the door without the frame for the glass, glass goes up it's final inch after the door has closed, lest is should hit the body.

Mustang window when you open/close door? - Yahoo! Answers

they could add something like that to finally close the door too. thankfully in my van all but two doors are motorized.

I have seen the sliding doors of a Mazda MPV close on its own once you just push it to the lock am not sure why they didnt add this for the normal doors as well.