Abstract :
I am surprised that Mr. Thullen has attempted to treat such a subject in so short a paper, because when one sees the mass of detail entering into the improved signal system it seems almost hopeless to attempt to describe it. The amount of detail looks discouraging and the expression of a number of our engineers (excepting the signal engineers) before the system was started was “How will the trains be kept running; it is so easy to stop them and so hard to get them started again?” For instance, we start out with a transmission line, a 60-cycle transmission line to the different sub-stations, and that was to supply ultimately, after passing through transformers, about 550 volts, carried to a main busbar running the whole length of the system. In addition to that, there are still in each sub-station motor-generator sets consisting of a direct-current motor operated from the busbar, and that directly connected to a small 60-cycle generator, which is held as reserve so that in case of failure of the 60-cycle power from the main power-house it can be supplied immediately from the sub-station by putting in one of the small motor-generators in each sub-station and synchronizing them. These in turn feed into the 550-volt, single-phase, 60-cycle pair of wires running the entire length of the subway. They in turn feed transformers, and these transformers supply 14-volt busbars running the entire length of the system. In addition to that there is another line of storage-batteries for supplying the lights and they in turn are fed from the third rail at different points. In addition to that there is a main air-pipe line which of course is controlled by the electrically operated signal system between interlocking and overlapping sections. There is such a mass of complication and detail that it seems absolutely hopeless to attempt to make any description of it. The record of performance of the 60-cycle relays in the Manhattan Railway system has been remarkably good- I think the actual record is something like 300 000 successful performances to one failure, and it is improving all the time. That in itself was on an absolutely new system when installed in the New York subway. In the subway system one track rail is used for the return current, what might be termed the traction current, and the other rail is insulated and is used only for the signal service.
