78Views13Replies

Author Options:

How do the gears in a car window prevent the window falling? Answered

Whether manual or motorised, I am gobsmacked that a gearing system has been invented that prevents falling that is not a worm drive. Its been impossible to find ANY information about the gearing system that explains this miracle on google. If its not a worm gear, why doesn't the window fall back down when you let go of the crank handle or cut power to an electric window?

Tags:gears

Discussions

0
None
bwrussell

Best Answer 2 years ago

Have you been searching by randomly smacking your hands on the keyboard? :D Found THIS immediately.

Car windows do use worm gears is the simple answer.

0
None
zxenDownunder35m

Answer 2 years ago

I agree. When you're an inventor, finding the right parts and solutions to problems is EXTREMELY hard.

0
None
zxenbwrussell

Answer 2 years ago

The small images in your linked article are not discernible to see how to recreate the mechanism. Any worm threads are shielded by housing. Thanks for trying, but I really need a clear image to see how its working, preferably a video or animation.

0
None
zxen

2 years ago

It appears that when researching car window gears on the internet, the regulator that keeps the window steady is the main thing described. However, if you know that it uses a worm drive (like a tuning peg on a guitar - a threaded screw that locks into the teeth of a spur gear) then its easy to look up. Google needs you to already know the answer to questions before you can know the correct words to type. I wish Google was able to provide answers when a description was made instead.

0
None
Yonatan24

2 years ago

Maybe for the same reason that you can't turn many types of drills when they're off. Probably some kind of lock.

0
None
rickharris

2 years ago

In any gear system if the step down is high enough (and it is because the motor will turn very fast) then the gears will be trying to drive the motor at 3000 + RPM - This involves a lot of power (try turning the output shaft of any slow running electric motor.) The weight of the window will not have sufficient potential energy to use gravity to over come the gear drag. - The slides for the window also add drag and friction.

Worm gears are an excellent way to get a BIG step down with very few gears and is often used. Worm gears as you say can not be driven by the output shaft.

0
None
zxenrickharris

Answer 2 years ago

Thank you. I was wondering why some of my heavy duty servo motor shafts could not be rotated by hand. This is an inconvenient reality, because I was hoping to create a braking system for my small hobby servos at a 1:1 ratio that I hadn't explored yet. If windows simply rely on this principle, then I would only be able to achieve a small arc of rotation.

Hang on a sec. I know how the screw in worm gears stop the spur from rotating, but you say that any gear system with a big enough ratio step down will create a holding brake effect. This is not going to help me in the case of hobby servo braking because I only have 200 degree arcs to begin with. Stepping down even further would mean a much smaller arc of movement, making the motors useless.

I am still yet to see a clear animation of how the gears in the window are set up.

0
None
rickharriszxen

Answer 2 years ago

A small hobby servo relies on a continuous signal to maintain position. that's how they are designed.

If you want to hold them in a given position against some external force then you will have to provide an external mechanical brake. Not easy in miniature size.

Often it helps to describe your real problem.

I see you have been asking this question for some time with a much similar result, - that should tell you something, Perhaps your approaching your problem, whatever that may be in the wrong way and a redesign is in order.

https://forum.pololu.com/t/hobby-servo-braking-ser...

0
None
zxenrickharris

Answer 2 years ago

I've seen this video that never shows the gearing many times. Infuriating video that keeps popping up all over the place.

0
None
verence

2 years ago


> If its not a worm gear, why doesn't the window fall back down when you
let go of the crank handle or cut power to an electric window?

Friction. The curse of all perpetual machines.


0
None
zxenverence

Answer 2 years ago

Yes, friction...