Relay Logic - Siding end w ext. Dwarf Absolute Signal

This is an example of the relay logic used to operate a railroad wayside dwarf signal at a control point for a Siding end with an extension track that continues on a straight alignment. Essentially therefore to return to the Main line a train must proceed through a crossover consisting of two turnout switches. Otherwise when a train proceeds on straight track, they will enter dark territory on the extension track. The toggle switches act as control signals coming from the dispatcher desk. One of these indicates the position of the turnout switches / crossover at the control point. The other two are block authorization which gives the signal the appropriate aspect. Dwarf aspects available are Stop, (Red) Restricting, (Lunar) Slow Approach (Yellow) and Slow Clear. (Green) It was brought up to me that most locations that carry this type of control point are done so with a Dwarf signal rather than your typical upright. I should mention that this circuit is designed for a dwarf signal. I illustrated a different circuit to express the same location on an upright signal. The purpose for this circuit is to demonstrate the relay logic more than the actual function of the signal. I apologize for the crudeness of the circuit as I only have wavelength-specific LEDs in the software. Therefore I substituted with a light blue or indigo colored LED for the lunar white aspect. Actual track circuits look nothing like this however the relay logic used here is very similar to what a signal would look like before the industry moved towards solid state. Explanation of switches: (Left to Right) 1 - 1st Block authorization. Coming from the dispatcher and allowed through electronic interlocking the first block switch will close to actuate the first series of relays and line up the signal depending on the switch position. 2 - Crossover Position. The turnout switches at the control point will either be lined for a diverging crossover movement toward the main line or both are lined for straight movement where this movement will proceed out of signaled territory and into the extension track. 3 - 2nd block main route authorization. When the switch is closed it will line up the signal to show two blocks clear on the main line.

published 9 years ago