All About Inventions and Discoveries
The Romance of modern scientific and mechanical Achievements

i3o All About Inventions train pipe. At the same time the outlet from the brake cylinder to the open air is closed. Thus two definite functions have been carried out by the valve mechanism. Now a third movement occurs. This is the opening of the passage between the auxiliary reservoir and the cylinder carrying the brake piston. As the air within the auxiliary reservoir is compressed, while that within the brake cylinder is at the normal atmospheric pressure of 14 pounds per square inch, naturally the air rushes from the auxiliary reservoir into the brake cylinder. In so doing the piston in the brake cylinder is moved outwards and actuates the braking mechanism, causing the brake-blocks to come into contact with the wheels. When the driver desires to release the brakes all that is necessary is to admit compressed air into the train pipe, which opens the brake cylinder to the air, thereby permitting the compressed air in the latter to escape and the piston to move inwards and to remove the brakes from the wheels. At the same time, the passage between the brake cylinder and the auxiliary reservoir is closed, while that between the auxiliary reservoir and the train pipe is opened. Owing to the air- control mechanism performing three definite and distinctive functions, it is known as the “ triple valve.” It will be seen that this brake is absolutely auto- matic in its action. When it was first submitted to test, its superiority over the former or “ straight-air brake ” system was so pronounced as to force the original invention into the background. When a train breaks in half, the rupture of the train pipe, enabling the compressed air within the latter to escape, brings the auxiliary reservoir and the brake cylinder