Electrical Features of Block Signaling

L. H. Thullen
1905 Transactions of the American Institute of Electrical Engineers  
It is only within the last decade that electricity has played any important part in block signaling. Previously to that time the only electricity used in signaling was the current from a few batteries for the track circuit, and for the operation of pin-valve magnets in the electropneu-rratic system of signaling and interlocking. During the last few years the use of electricity for signaling has steadily increased. Now electricity is the chief feature of all signaling apparatus. A brief sketch
more » ... s. A brief sketch of the older methods of signaling will be first presented, as they are still in use, and therefore not without interest. TELEGRAPH BLOCK SYSTEM. The first system worthy of notice is what is known as the telegraph block system, which is yet extensively used, especially on single-track roads. In this system the road is divided into sections of a predetermined length, an average section or block being from one to three miles long. An operator is stationed in a tower at the entrance of every block, and by means of hand-operated signals gives the engineer of an approaching train a clear-caution-or stop-signal, as the case may be. Under normal conditions only one train is allowed in a block at a time. The operator allows a train to enter a block only'after he has receiv'ed information from the operator at the other end that all trains have cleared that block. This information can be given by means of a bell-signal, or by telegraph. 577
doi:10.1109/t-aiee.1905.4764553 fatcat:uif5lplvg5gmtd7kobra3cnvvu