GRS Type-J cTc code equipment:
(Thank You to Keith Huebner for the photos)

The Type J coding system provides the means for centralizing the control of switches and signals at remote field locations, subject to the safety features incorporated in the wayside signal apparatus and circuits. The system also automatically supplies information on the conditions of track occupancy, etc., existing at the field locations, thus enabling intelligent control from the central or control office.

The Type J system is simplex in operation, that is, the two-wire line circuit carries only one control cycle or one indication cycle at a time. Control cycle transmission from the office to the field takes precedence over indicaton cycle transmissions from the field to the office. For the transmission of both controls and indications, the step-by-step operation of the entire system is driven by the control office equipment. Controls are transmitted by polar codes applied to the line circuit; indications are transmitted by Mark-Space codes that are superimposed by the field locations on polar driving codes originating in the office.

The system can have 9 to 14 control functions and 10 to 16 indication functions per station, based on how many locations are configured on the system, with a maximum of 64 stations.

The coding system uses Type J relays
in the coding and application units.

One VTA line relay is also used at
each field location.

J Relay side view

VTA Line Relay (front)

VTA Line Relay (side)

Field Stepper Unit Close-up

Field Stepper Card

Field Stepper Card

Pulse Detector and Cycle Timer card

Pulse Detector and Cycle Timer card

Wadsworth Application Unit (above) and
East Wadsworth Stepper and end of
siding application unit (left)

The local control panel
mounted on the top of the
stepper unit for East

Thanks again to
Keith Huebner
for the pictures!