Engineering Wonders of the World
Volume I

230 ENGINEERING WONDERS OF THE WORLD. Fig. 10.—INTERIOR OF READING MAIN LINE EAST SIGNAL BOX. LEVERS FOR MANUAL SIGNALLING. put back the levers— especially point levers —continually ; and so some of the advan- tages gained by the operation of points and signals by power in- stead of manually will be appreciated. Mr. Westinghouse, the inventor of the air brake, first introduced the movement of points by power. This was done at Bound Brook, New Jersey, on the Philadelphia and Reading Railway, in 1884. back to normal until another lever has been restored. In the first instance considered, the lock prevented a lever being moved from normal so long as another was abnormal. A tappet may pass through two, three, or more locking boxes, or it may be made of double thickness to engage with, two superimposed, rows of locks and slide bars in a single box. The locks and notches are differently shaped, so that the locks of one row can enter only the corresponding notches in the tappets. In catch-handle locking the tappet is at- tached to the catch handle of the lever. Should the tappet be held by some conflicting tappet, a catch cannot be , , . lilted trom the quadrant, and Locking. consequently the lever cannot be moved. This system puts less strain on the interlocking, but introduces links, pins, and other moving parts. POWER AND AUTOMATIC SIGNALLING. The view in Fig. 10 will give an idea of the size of present-day signal boxes. It may also help us to realize the physical strain put upon the signalman by his having to pull over and Compressed air, and subsequently water, Fig. 11.—ELECTRICAL POWER LOCKING FRAME ON THE NEW YORK CENTRAL RAILWAY. FRONT REMOVED TO SHOW INTERLOCKING GEAR.