Why does punching an appliance sometimes seem to fix it?

Question

So I live in military barracks and i have a shitty fridge in my room. It started making this horrible noise, and out of desperation I landed a solid right hook to the side of it. Like magic, the noise stopped. This has happened numerous times in my life. Something is broken, and some brute force fixes it. What happens inside that could solve the problem from percussive force?

In: 239

Answer 1

Despite the myriad of amazing modern devices, a lot of the failures they can experience are very similar, and the “fixes” for those things are often simple and applicable to lots of different types of equipment.

For electrical connections, sometimes there may be a small bit of corrosion preventing continuous good contact, and a little movement might be all that’s needed to shake some corrosion away or move the contacts enough to temporarily get good electrical contact again.

For rotating equipment, there may be a slight misalignment causing rubbing or vibration, and a little mechanical agitation might be enough to jostle the offending rotating equipment enough to temporarily keep it from rubbing or vibrating.

In fluid systems, like your refrigerator, there may be some small blockage that temporarily impedes flow causing cavitation noises. Shaking the flow obstruction might break it free, restoring unrestricted flow and making the noise go away.

Some systems rely on little mechanical switches or devices to change how the system operates. Your toilet has a float valve that stops water going into the back of the toilet when level gets high enough, for example. Those things can get physically stuck sometimes, and a little shaking gives it just enough momentum to overcome friction or whatever is sticking it. This could be a valve like in your toilet, or a little electrical relay in your car, or any of a million different things.

There’s infinite different scenarios where physical force is the solution, these are just some generic ones I could think of off the top of my head. Generally speaking, none of these things are actually fixes. Whatever is causing the noise, vibration, rubbing, sticking or whatever will still need some actual fixing to make it permanently go away, but sometimes a little slug or kick will get it going for a bit longer and sometimes that’s all you need.