section_path: Components/Brakes
section_name: Brakes
paragraph_text: Brakes
  
  Because trains are heavy, powerful brakes are needed to slow or stop trains, and because steel wheels on steel rails have relatively low friction, brakes must be distributed among as many wheels as possible. Early trains could only be stopped by manually applied hand brakes, requiring workers to ride on top of the cars and apply the brakes when the train went downhill. Hand brakes are still used to park cars and locomotives, but the predominant braking system for trains globally is air brakes, invented in 1869 by George Westinghouse. Air brakes are applied at once to the entire train using air hoses.