Brake Cylinder: Piston with Packing Leather, Expander Ring and Release Spring (Westinghouse Air Brake Co., 1901)

The air cylinder that puts on a railway car's brakes. Air let into the pressure end drives the piston out, and its push rod works the brake levers. When the air is let out, a release spring pushes the piston back. A cup of leather, held against the wall by a spring ring, stops the air from leaking past the piston. Result: a brake cylinder. In the book's driver-brake example, an 8-inch cylinder fully applied puts 2,500 pounds on its piston. Source: Westinghouse Air Brake Company, Air Brake Instruction Book (1901), pp. 55-57 and 97. Unknown: every size except the 8-inch bore, and the metal of every part except the leather; the book does not give them. Picture: Wikimedia Commons.