From the first moment in which the human being began to wonder about things, a development process began in which we still find ourselves. We are rational animals that ask ourselves questions and that interest in what we don’t know makes us advance as individuals and sometimes as a society. Curiosity is what probably led you to open this article or search for it on the Internet asking yourself what is the reason for that sound in my car when it goes in reverse?
There are many examples on the Net of that reversing sound. In this video we can perceive that Noise like a zipper closing very quickly. But that sound only occurs when the car is in reverse, the rest of the gears do not sound like that. Why is it? It has a very simple solution and it has the answer in the gears.
If we think about the majority of transmissionsall of them are usually a helical geari.e. diagonally. The teeth are angled, like the first image below. The teeth are constantly in contact and this reduces noise so they move from one to the other in complete silence.
On the contrary, the reverse gear does not have this gear but is built with the spur gear. This is cheaper to produce and the reverse you need three gears to reverse the direction movement That is why it is more practical and economical for the manufacturer to use this type of gear for the reverse gear. Being straight teeth, each time they interlock like a zipper a noise is produced that is what we hear every time we reverse gear.
That’s right, the sound is just the friction that the teeth make when fitting between them when dealing with a spur gear since they do not have the same smooth greasing that the worm gear has. If listened to one by one individually it would sound like a small “click” of engagement that becomes the final sound that becomes more and more audible the faster the vehicle goes.
Are all cars like this? No. In fact, some racing cars feature spur gears in all of their transmissions to save weight. The helical type of gear requires stronger transmission casings to reduce the end load or thrust force generated by these types of gears. In the video you can clearly hear it, thank goodness you don’t have to use the vehicle daily, otherwise you would have to spend a lot on headache pills.
Source: Jalopnik
