A lot of automotive jobs become so much harder the moment a part won’t come off the way it’s supposed to. Our David Tracy detailed when a man spent three days trying to remove an oil filter. In the process, that wrencher used a tool we should all probably have in our toolboxes.

Over the last few weeks we clamped things down with the classic and still incredibly useful , substituted the floor jack with the and moved our car projects around with ease with . This week’s Cool Tool is the air hammer, the tool you can use when nothing else gets your parts off.

You have been asking for more air tools and your wish is my command.

Some wrenching jobs almost always end up being more work than they should be. You look at what should be the work involved and it looks like something you could knock out in just a couple of hours. Then before you know it you have a broken car, tools laying around everywhere and you’re racing to the parts store before it closes at 10:00 p.m.

Or, if you’re the poor fella from David’s , you’re three days deep into getting an oil filter off just so you can do a simple oil change.

I faced a similar issue early last year when I was replacing the wheel bearings on my fiancée’s then Chevrolet HHR.

See, the HHR is supposed to have hardened steel hub assemblies with wheel bearings. You should be able to zip off a bunch of bolts, slide the old hub assembly off, then slide the new one on. But these are known to get stuck, effectively welding themselves to the steering knuckle.

Galvanic corrosion is a wonderful, yet aggravating process. Take dissimilar metals, slap them together, then feed them a healthy dosage of water. One metal acts as an anode while the other acts as a cathode. Before long, you have two pieces of metal that may as well be welded together. In this case, the hub and the knuckle end up fused and the only way out may be through brute force.

Thankfully, my good friend had a weapon of mass destruction on hand: an air hammer.

These work by using compressed air to move an internal piston through a chamber. That piston transfers force to the head, which beats whatever part you’re working on into submission. In David’s story, with help from heat it meant that the oil filter finally came off.

For us, it meant cutting through the fused metals just to get the hub assembly loose. It didn’t look pretty and it took well over an hour of non-stop hammer action. But in the end, the job was successful.

It helps that you feel like a mad scientist and that perhaps you really can fix anything with a hammer. You can also use an air hammer’s attachments to carve out stone or to slice through metal.

The air hammer used by my friend is of the tool truck variety. But thankfully you don’t have to pay tool truck prices. They can cost anywhere between $ and $ depending on how big of a job you need them to handle. Of course, you do need an air supply setup at home to use this. How much air you need may vary between the tools.

Do you have an air hammer? If so, tell us what you use it for.

And, do you know of a weird or unique tool that wrenchers can benefit from knowing about? Do you want to see us put a type of tool to the test and see how it performs? Shoot me an email or drop it down in the comments!

A previous version of this story said that the HHR’s hubs are aluminum. These are actually hardened steel. However, they still have the aforementioned galvanic corrosion that makes disassembly difficult.