Why do car doors have a half-closed state

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It’s very annoyng when a car door doesnt close properly, and I think it could be avoided with a better locking mechanism. Why is it that most doors can close at once but car doors are more complicated?

In: Engineering

6 Answers

Anonymous 0 Comments

So if, for whatever reason, the door doesn’t close all the way it doesn’t fly open while you’re driving. It’s a redundancy.

That said some high end cars will pull the door the rest of the way for you.

Anonymous 0 Comments

~~Because sometimes you need it.~~

~~Take this morning for me as an example. It was an icy morning and I needed to scrape my windscreen. For context, I’m parallel parked on a roadside space.~~

~~I got in and started my car to get it warm, and then got back out again to start clearing. As all my windows were iced up, I couldn’t see if it was safe to get out of my car again. Leaving the door ajar allowed me to look back. It also meant that oncoming traffic was aware that someone may be getting in and out of the car and to pass with care. But it also meant that my door wasn’t fully open and completely obstructing the main road.~~

~~This is just one of many instances where being able to keep the door ajar without a hand free is helpful.~~

~~I’m not sure I understand your hypothesis either that this somehow makes car doors harder to close…~~

Edit: Apparently I misunderstood OP.

Anonymous 0 Comments

Car doors have to withstand constant vibration, wind, and rain. That is why they have thick, soft rubber seals all the way around. It takes some force to push it tight so that the seal holds. Other doors can have the same kind of seals, but are usually so heavy that they will fall into the latch once you set them in motion.

And then, as others have already said, there is a secondary mechanism that can keep the door from opening all the way if the lock fails while the vehicle is in motion. That’s the “half-closed” state.

Anonymous 0 Comments

Car door locks are designed to keep the door shut during an accident for safety. They are pretty heavy duty and that’s why they require a small amount of force to engage properly

Anonymous 0 Comments

Many comments misunderstand. I’m with OP. It’s either latched or it isn’t. If it’s the rubber seal thing then it shouldn’t half latch.

Anonymous 0 Comments

So when you close the door slowly your hands do not get sandwiched. Not really a stressful thing in the car.