Let's say a pioneer's going down a wagon trail and the wheel of falls off. What would he do to put it back on or change it out for a spare if it breaks completely? I suppose if he's lucky then there might be enough people around to lift the wagon off the the ground but would there be anything he could do if it's just him?
There was the classy wagon jack. The rack-and-pinion system was able to quickly lift the weight of a freight wagon. But there was also the simpler wagon or buggy jack- not nearly as sturdy or strong, but also not a difficult thing to make - no forged-and-fitted rack, pinion, crank, etc.
And, if you contemplate them, you'll realize they're both based on the lever: the simpler one is just outfitted with a base to keep it ( hopefully) from tipping and a series of steps to fit any number of heights. So, beyond these devices, you can imagine Harry and Bill just borrowing the top rail of a split-rail fence for a lever, so they could deal with their disabled wagon on the National Road in 1830, and setting the axle on a rock, or a keg. And, we'd hope, putting the rail back when they were done.