Article: The Capstan Wheel - Interlocking - 1888

From the Railroad Gazette January 18, 1888

The cost of equipping grade crossings on the above principle was so high as to prevent railroad companies from taking advantage to any great extent of the laws allowing them to run the crossings without first making a stop.

To reduce the cost to any great extent it was necessary to have a cheaper machine and cheaper connections. This was done by the invention of Mr. Henry Johnson, which consists of capstan wheels instead of levers, and wire connections entirely instead of part wire and part pipe. A large number of these machines has been manufactured and put into service by the Union Switch & Signal Co., and while their actual use has demonstrated some weaknesses, all of which can be remedied, the principle has proved so satisfactory that there is no doubt they will be used almost exclusively for simple systems of signaling.

A complete description of this device will be given at another time, but briefly stated the capstan wheel does the work of four levers. It has five positions and works switch, facing point lock, home and distant signals. When setting the track and signals for a train the capstan wheel is pulled by the operator and first the switch set, then the facing point lock, then the home signal and last the distant signal. By these separate movements the capstan wheel gives exactly the same results as levers would, except that the latter can be handled much more rapidly. For that reason it is probable that levers will always be used at places where trains are required to be handled rapidly. The connections to the switches and signals consist of a continuous cable from the capstan wheel to the distant signal, connecting by means of a motion plate the switch and facing point lock, and the home signal by means of a rotary wheel, of which one is also fixed on the distant signal.

Four of these capstan wheels are required for a plain single or double track crossing having derailing switches. Two capstans only are required when there are no derailing switches. If there are no derailing switches and no distant signals, one capstan wheel will work the four signals, but in this case the two signals that are not conflicting are lowered at the same time.

The interlocking between the wheels is done just as it would be between levers and on the Stevens principle. This arrangement is certainly the cheapest that has been devised giving complete interlocking.

From the Railroad Gazette, January 18, 1888