If you have just a few plants worth of dry beans to thresh, you might break the pods open by hand. You might even do this with a small pile of beans, especially if the pods or beans are particularly large, or if the beans are pole types that were harvested as dry pods instead of cut as whole dry plants. Especially if it is comfortable to thresh in your living room, and you can visit with others as you companionably hand thresh beans together.
With a bigger pile of dry bean plants the standard approach is to pile and thresh the beans on tarps. People talk about stomping on or dancing on the beans. But actually, it is a rolling motion of the foot that threshes out the beans most effectively. Ideally, you layer the beans about one or two plants deep, stand on one part of the plants, and roll your foot over the other part. (Wear clean shoes with treads too shallow to catch beans.) This rolling motion is more laborious and tiring than stomping or walking. Nevertheless, it is relatively easy to thresh out several pounds of beans in a session rather than just handfuls. (Cleaning and winnowing threshed piles of beans and debris requires nothing more than appropriate containers and a fan. For cleaning and winnowing, see the bean chapter in The Resilient Gardener: Food Production and Self-reliance in Uncertain Times. It's threshing the beans, that is, breaking open the pods and releasing the beans, that is the hard work.)
But what if you have bigger batches of beans? What if you are growing all the dry beans for your family, and you eat beans as a major staple? Then you need to be able to thresh a few hundred pounds of beans. This is still way too few for a grain combine, even if your beans were all one variety and you owned a combine, and they probably aren't, and you probably don't. This is the situation I faced this year. I simply had too many beans to thresh by foot on tarps any more.
There are plans on the internet for a small-scale bean and grain thresher made by converting a chipper-shredder. I was expecting that the answer to my bean problem was going to involve needing to make one of these. But before undertaking that project, I decided to ask everyone I know who grows larger amounts of beans (thousands of row feet of individual varieties, but not thousands of acres) how they thresh their beans. I was expecting that they all had some version of a small-scale thresher - the converted shredder or antique equipment or something else jerryrigged but mechanical. I talked with about two dozen people and heard tell of at least two dozen more farms operating at the relevant scale. Here's the result: NOBODY is using a small scale thresher. They are all just driving on their beans.
Even those who have the converted chipper-shredder threshers don't use them. The thresher requires feeding plants by hand into the hopper a few at a time, so it really isn't any faster than stomping the beans on a tarp, which does not require handling individual plants. In addition, the pounding instead of rolling motion of the thresher cracks and breaks a lot of the beans.
Even those who are growing an acre or two per variety and who own combines are not using their combines for the beans. They use the combines for grain. They drive on their beans. The combines crack and break too many beans. (Those growing thousands of pounds of beans do combine them, and just live with a lower grade product than those of us who produce small amounts by hand.)
Most people just leave the piles of beans on the tarps onto which the dry plants are piled and stored until time for threshing. Then they drive over the beans with a tractor or pickup truck, that is, something with a high wheel base. One fellow with a few acres of beans built a special concrete pad for driving on his beans without tarps. He sweeps each batch of beans up after the driving. But most people put the tarp with dry beans on a driveway or in a barn and drive on the pile of beans right on the tarp.
So I started driving on my beans. It works great. It does crack or break some beans of some varieties. However, so does stomping by foot. Various factors affect the amount of damage. I have found that I get less (or no) damage if I have a thick layer of matted down bean plants instead of a shallow layer. I also orient the wheels of the vehicle carefully as I drive back and forth over the piles of beans on the tarp so that I am driving over most bean pods just once instead of several times. Just one drive over the beans is very effective. The wheels themselves impart a small rolling motion that is ideal for threshing out the beans. (Of course, you want to use all the tricks I describe in the bean chapter of The Resilient Gardener so that your beans will be as dry as possible when you thresh. Damp beans don't thresh.)
I'm using my Toyota minivan to thresh the beans. With it, I can have the beans piled up to about a foot high. If I had a tractor, that would be even better, presumably. The higher wheel base would allow dealing with a bigger pile of beans at once without any catching and dragging off the pile.
Summary: For bigger batches of beans, just drive on 'em.