21: A Pennsy T1 4-4-4-4 drifts into Lebanon station with a
passenger train.The passenger station is on the left and the
freight house is across the tracks in this photo.
21
within reach of the aisles are manually operated by Caboose
Industries ground throws.
The railroad has an operating signal system with PRR-style
position-light signals. I designed the detection circuits myself,
and there are 45 relays that drive 26 signal heads. Occupancy
detection in 3-rail is really easy, by the way. The three rails are
all electrically isolated from each other. The middle rail is “AC
hot” and one of the outside rails is “AC common.” The other
outside rail is available for the signal system to use.
On 3-rail cars and locomotives, the wheels are not insulated
from each other. Whenever any piece of rolling stock is in
a block, the wheels and axle make an electrical connection
between the “AC common” rail and the signal system’s rail.
Pennsylvania & Western RR - 13
22: An E6s 4-4-2 is preparing to make a station stop at
Franklin on the Cumberland branch with train 52.Trains on
the branch are assigned smaller motive power than those on
the main line due to weight restrictions on a bridge entering
Cumberland.The Franklin freight house is on the right.
22
Adding a relay is all that’s needed for detection; no current
sensing is required.
In addition to occupancy detection, the system incorporates
some toggle switches to override signal aspects. The Annville
yardmaster has fascia-mounted toggles to control the east
and west approach signals entering the yard. Towns on the
main line have toggles that control approach signals to the
town. When the dispatcher gives a local train permission to
work, he instructs them to set the approach signals. The tog-
gles set the signal aspects to “stop” and also display a red LED
on the fascia.
MRH-Mar 2014
