NJ International 8001 Servo Master Activation System For Crossing Gates & Semaphores

TDP offers sensor expansion kits for the ServoMaster to allow the operation of a grade crossing on up to four bi-directional tracks (Stock # 8001 for optical sensors). The expansion kit will add a printed circuit board and one additional sensor cable giving you two additional pairs of start and hold sensors. This gives the system four sensor pairs for use on four tracks in one direction or two tracks in both directions (or any other combination of the four sensor pairs such as a center bi-directional track with the outer tracks being single directional on a three track railroad). Adding a second expansion kit will add an additional sensor cable giving you six pairs of sensors. To fully expand the system to eight pairs of sensors you need to add one additional sensor cable (stock #8002 for optical sensors).

The expansion board is actually two identical boards in one as shown above.