Free up a Stuck Trailer Hitch
When the ball mount on your trailer hitch is rusted in place, don't whack at it with a sledgehammer. Here's what to do instead. Buy a can of CRC Freeze Off penetrating spray, an air chisel and a hammer bit.
Spray the opening to the hitch receiver. This newest style of penetrating fluid chills the metal, causing it to contract to help break the rust seal. Then use the air chisel fitted with the hammer bit to knock everything loose. The air hammer will break up the rust, spread the penetrant and free up the ball mount. Once it's free, just tap the rusted ball mount out with a hammer. If you plan to reuse the rusty mount, coat it with a rust converter or waterproof marine grease.