Mechanical piston drills employing attached bits on drill rods and relocating up and down just like a piston in the cylinder date from 1843. In Germany in 1853 a drill that resembled fashionable air drills was invented. Piston drills were superseded by hammer drills run by compressed air, and their https://mylestmdte.tinyblogging.com/automotive-catalysts-things-to-know-before-you-buy-80250405