A Pea Sheller is a machine that automates getting peas out of their pods. It can save the hours of manual work required to reduce several bushels of peas in the pod down to two small bowls.
The machines are not just for English garden peas. They can be used for field peas, lima beans, etc.
They can be electric, or ones operated manually with a hand crank. In the 1930s, Pea Sheller appeared that you attached to a stand mixer, with the axis of the mixer powering the machine.
The general idea with all Pea Shellers seems to be the pods get fed through rubber rollers, which squeezes them just enough to make the peas pop out, without squishing the peas.
Some people made their own from old wringer-washers.
Commercial ones can spew out upwards of 1100 pounds (500 kg) an hour.They are seldom used in homes anymore because people buy their peas already shelled now.