Drag

Drag, a mechanism for slackening the speed of carriages, by operating on one or more of the wheels. The form of drag best known to old travellers by coach was that of the 'shoe,' a hollow piece of iron attached by a chain to the carriage, which being put below one of the hind wheels partially reduced the vehicle to the nature of a sledge; by which dragging process the carriage was suitably retarded on going down-hill. As the shoe-drag required to be applied and removed with some inconvenient detention of the vehicle, a step was made in advance when a method of retarding a wheel without detention was discovered. This new process, which is known as the patent drag, consists of a connected piece of mechanism, altogether operated upon by the driver without moving from his seat. A handle affects a series of rods and levers by which a block is pressed against each of the two hind wheels, so as to slacken their motion. Such is the kind of drag now very generally attached to cabs and gentlemen's private carriages. It is of French origin. In the case of vehicles used for heavy loads, the levers are worked by a handwheel and screw instead of a handle. Tram-cars have four shoes applied to as many wheels by a system of levers moved by a handwheel and chain, and locked by means of a ratchet and catch. In addition, tram-cars have now an emergency brake, worked by a compressed spiral spring, which can be released by touching a catch with the foot. See BRAKES.