After looking at some pictures of a modern electric railroad jack positioned to raise a railroad car, I thought that these machines are so useful. They are portable and not all that big. It's surprising that they could lift up a railroad car.
I wonder who thought to invent something so useful. The first ones seemed to work well, even though they were operated by hand. Railroad jacks are used for the same purposes today as when they first invented. They have been modernized by adding hydraulic or electric lifts. Derailments, accidents and repairs call for the need to lift up the railroad cars.