This section covers the
various circuit symbols used in the signal drawings, and the nomenclature used
to describe them.
The majority of information for this page came from a
book labeled Graphical Signal Symbols and Written Circuit
Nomenclature,
published by The
Railway Educational Bureau in 1950, and written D. C. Buell.
This first section deals
with the standard AAR abbreviations and nomenclature used in the labeling of
relay drawings. If you have ever tried to read a signal drawing, and can't
make sense out of it, these "TLA's" should help you.
General
AAR Abbreviations
A Approach B Block, button,
positive energy (hereafter referred to as power) C Common,
changer, counter, correspondence, circuit, controller, code, checking
contacts D Proceed indication of a signal, detector,
decoding E East, eastward, electric light,
element F Traffic G Green, signal
(operating mechanism), ground H Home, Approach indication
of a signal J Skate, dual
control K Indicator L Left, lock
preventing initial movement of a lever from normal or reverse position, locking,
lever, light, split battery, lock valve M Lock preventing final
or indicating movement of a lever, magnetic, marker N
Normal, north, northward, negative O Order, operating, off,
overload, out P Pole, power, purple, push, repeating,
primary Q Local or secondary coil (as in double-element
relay or mechanism) R Right, red, reverse, relay, power
operated controller or contactor, route, stop indication of a
signal S South, stick, storage,
southward T Track, time, train, telephone, transformer,
transmitter U Retarder, unit V Train
stop (track element), electro=pneumatic stop valve W Switch
(operating mechanism), west, westward, white X Crossing,
interlocking, bell, buzzer, AC Y Slot, yellow, hold
clear Z Use for any special terms (to be noted on
plan)
Energy
Wires
C
Common
DC.
EC
Common
East, meaning DC from system east (likewise for north, south, and
west).
FC
Common
traffic locking.
CX
Common
AC.
ENX
Negative
voltage AC from POR for lighting, or east negative AC power (likewise for
north, south, and west).
NX
Negative
AC power.
BL
Positive
side of split battery.
NL
Negative
side of split battery.
CL
Common
of split battery.
N
Negative
of DC power.
B
Positive
of DC power.
EB
Positive
power east (likewise for north, south, and west).
BB
Battery
- second battery.
BBB
Battery
- third battery.
BX
Positive
AC power.
EBX
Positive
AC power from POR for lighting, or east positive AC power (likewise for
north, south, and west).
Operated
Units Relating To Track Circuits
T
Track section.
TR
Track relay.
TPR
Relay repeating track relay.
TPPR
Relay repeating track repeating relay.
TSR
Track stick relay.
TSPR
Relay repeating track stick relay.
BPR
Block repeater relay, relay repeating the track
circuits in a block.
BK
Block indicator.
Wires Relating To Track
Circuits
TB
Track positive - positive power to
rail.
TN
Track negative - negative energy from
rail.
RB
Relay positive - wire from positive rail to
relay.
RN
Relay negative - wire from negative rail to
relay.
TO
Positive control of local coil, double element AC
track relay.
TP
Positive control of TPR
TPP
Positive control of TPPR.
TPS
Positive control of TPSR.
TK
Positive control of TK.
BP
Positive control of BPR.
WB
Positive rail to switch circuit
controller.
WN
Negative rail to switch circuit controller.
Operated Units Relating To
Switches
W
Switch operating mechanism or lock
valve.
WR
Relay, controller, or contactor
controlling both normal and reverse operations of a switch or an
electric switch lock.
WNR
Relay, controller, or contactor
controlling the normal operation of a switch or an electric switch lock.
WRR
Relay, controller, or contactor
controlling the reverse operation of a switch or an electric switch
lock.
WRPR
Relay repeating WR.
WNRPR
Relay repeating WNR or normal position of WR.
WRRPR
Relay repeating WRR or
normal position of WR.
WPR
Relay repeating position of a
switch.
NWPR
Relay repeating normal position of
a switch or normal position of WPR.
RWPR
Relay repeating reverse position
of a switch or reverse position of WPR.
WK
Indicator indicating the position
of a switch.
WL
Switch lock operating mechanism of
a switch.
NWLPR
Relay repeating normal position
of a switch lock.
NJPR
Relay repeating normal position of
a dual-control lever.
RJPR
Relay repeating reverse position
of a dual-control lever.
NWK
Indicator indicating the normal
position of a switch.
RWK
Indicator indicating the reverse
position of a switch.
WAK
Indicator indicating the condition
approaching a switch.
RWLPR
Relay repeating reverse position of a
switch lock.
WCR
Switch correspondence relay.
Wires Relating To
Switches NW Normal control of switch
operating mechanism. RW Reverse control
of switch operating mechanism. N10W Individual return wire to 10
switch operating mechanism. WR Positive
control of WR. N10WR Negative control of
10WR. WNR Positive control of
WNR. WRR Positive control of
WRR. WRP Positive control of
WRPR. WNRP Positive control of WNRPR. WRRP
Positive control of WRRPR. WP
Positive control of WPR. N10WP Negative control of
10WPR. NWP Positive control of
NWPR. RWP Positive control of
RWPR. NWLP Positive control of
NWLPR. WK Positive control of
WK. N10WK Negative control of 10WK. NWK
Positive control of NWK. RWK Positive control of
RWK. WA Positive control of
WAK. WL Positive control of
WL. RWLP Positive control of
RWLPR. WC Positive control of
WCR. NJP Positive control of
NJPR. RJP Positive control
of RJPR.
Operating Units Relating To
Signals HR
Relay controlling approach indication of a three position signal,
or the proceed indication of a two signal in one arm
signaling. DR
Relay controlling proceed indication of a
signal. HDR Relay controlling
approach and proceed indication of a
signal. HPR Relay repeating
HR or approach and proceed indication of
HDR. HSR Home stick
relay controlling the approach indication of a
signal. DPR Relay
repeating DR or proceed indication position of
HDR. RGPR Relay repeating signal
mechanism at stop. HGPR Relay
repeating signal mechanism at approach. RHGPR Relay
repeating signal mechanism at approach and
stop. DGPR Relay repeating signal
mechanism at
proceed. RGK Indicator
indicating signal mechanism at
stop. HGK Indicator
indicating signal mechanism at
approach. DGK Indicator
indicating signal mechanism at proceed. ETOHR
East train order HR (likewise for north, south, and west). ETOHDR
East train order HDR (likewise for north, south, and
west). ETOPHR East train order repeater HR (likewise for
north, south, and west). ETOPDR East train order repeater
DR (likewise for north, south, and west). HDGPR
Relay repeating signal mechanism in the approach and proceed
position. HDGK Indicator indicating
signal mechanism in the approach and proceed
position. HY
Hold clear or retaining mechanism of the approach indication of a
signal. DY
Hold clear or retaining mechanism of the proceed indication of a
signal. HG
Approach indication operating mechanism of a
signal. DG
Proceed indication operating mechanism of a
signal. RG
Stop indication operating mechanism of a signal.
Wires Relating To
Signals H
Positive control of
HR. D
Positive control of DR. HD
Positive control of HDR. N10HD Negative control of
10HDR. HP Positive
control of HPR. HS
Positive control of HSR. DP
Positive control of DPR. RGP Positive control
of RGPR. HGP Positive control of
HGPR. DGP Positive control of
DGPR. ETOH Positive control of ETOHR. ETOHD Positive
control of ETOHDR. ETOPH Positive control of ETOPHR. ETOPD
Positive control of ETODR. HDGP Positive control of
HDGPR. HDGK Positive control of
HDGK. RGK Positive control of
RGK. HGK Positive control of
HGK. DGK Positive control of
DGK. HG Positive control of
HG. DG Positive control of
DG. RG Positive control of
RG. N10HG Negative control of
10HG. HY Positive control of
HY. DY Positive control of
DY. RHGP Positive control of RHGPR.
Stick, Traffic, and Directional
Operated Units
SR
Stick relay.
ESR
East stick relay, likewise north,
south, and west.
LSR
Locking stick relay.
EASR
East approach sticking relay,
likewise north, south, and west.
ASR
Approach stick relay.
FL
Traffic lock preventing initial
movement of a traffic lever from normal or reverse.
FLM
Traffic lock preventing initial
movement of a traffic lever from normal or reverse and also preventing
final or indicating movement of same lever.
FR
Traffic relay.
FLR
Traffic lock relay controlling FL.
FLMR
Traffic lock relay controlling FLM.
FLK
Traffic lock indicator.
FSR
Traffic stick relay.
EFSR
East traffic stick relay, likewise
north, south, and west.
Wires Relating To Stick, Traffic,
and Directional Operated Units
S
Positive control of SR.
ES
Positive control of ESR.
LS
Positive control of LSR.
EAS
Positive control of EASR.
AS
Positive control of ASR.
FL
Positive control of FL.
FLM
Positive control of FLM.
F
Positive control of FR.
FLR
Positive control of FLR.
FLMR
Positive control of FLMR.
FLK
Positive control of FLK.
FS
Positive control of FSR.
EFS
Positive control of EFSR.
Operated Units Relating To
Indicators, Locks, Indication Magnets, and Relays Used For Locking
Purposes
M
Lock preventing the final movement
of a lever.
L
Lock preventing the initial
movement of a controlled function or lever.
NK
Normal indicator indicating normal
position of a unit.
RK
Reverse indicator indicating
reverse position of a unit.
TER
Time element relay.
NM
Lock preventing the final movement
of a lever to the normal position.
RM
Lock preventing the final movement
of a lever to the reverse position.
NL
Lock preventing the final movement
of a lever or a controlled function from its normal position.
RL
Lock preventing the final movement
of a lever or a controlled function from its reverse position.
LR
Relay controlling L lock.
LPR
Repeater of L lock relay.
MR
Relay controlling M lock.
MPR
Repeater of M lock relay.
TE
Time element.
TESR
Time element stick relay.
LK
Lock indicator repeating electric
locking.
TEPR
Relay repeating energized position
of TE.
TECPR
Relay repeating checking contact
of TE.
Wires Relating To Indicators,
Locks, Indication Magnets, and Relays Used For Locking
Purposes M
Positive control of
M. L
Positive control of L. NK
Positive control of NK. RK
Positive control of
RK. TE Positive control
of TER. NM Positive control
of NM. RM Positive control of
RM. NL Positive control
of NL. RL Positive
control of RL. LR
Positive control of
LR. LP Positive control
of LPR. MR Positive control
of MR. MPR Positive control of
MPR. TES Positive control of
TESR. LK Positive
control of LK. TEP Positive control
of TEPR. TECP Positive control of
TECPR.
Operated Units Relating To Highway
Crossing Signals
XX
Crossing bell.
EXR
Eastward interlocking or crossing
relay, likewise north, south, west.
XG
Wig-wag mechanism - crossing gate
mechanism.
XY
Slot
for wig-wag mechanism - crossing gate
mechanism.
EOR
Electric light operating relay
(flasher relay).
XSR
Directional relay to hold crossing
signal clear as train recedes from crossing.
Wires Relating To Highway Crossing
Signals
XG
Positive control of
XG.
RXG
Reverse control to XG (drive down
mechanism).
E1
Postive wire to No.
1 unit of flashing light signal (to be designated by letter N, E, S,
W).
E2
Postive wire to No. 2 unit
of flashing light signal (to be designated by letter N, E, S,
W).
XS
Positive control of
XSR.
EX
Positive control of
EXR.
EO
Positive control of EOR.
Operated Units Relating To Approach
And Annunciating Of Trains
AX
Annunciator
indicating approach traffic.
EAX
Eastward annunciator indicating approach of eastward traffic, likewise north, south, and
west.
AER
Relay used for approach lighting.
Wires Relating To Approach And
Annunciating Of Trains
AX
Positive control
of AX.
EA
Positive control of EA.
E
Positive control of ER.
Miscellaneous Operated
Units AK
Approach indicator. AR
Approach relay. PCR Pole changing
relay. NLPR Relay repeating the normal position of a
lever. RLPR Relay repeating the reverse
position of a lever.
E Electric
light. TO Train
order. WTO West train order signal governing
westward traffic, likewise north, south, and east.
RR Route
relay. VR Train stop
relay. VSR Train stop stick
relay. VPR Train stop retaining
relay. VY Train stop
retaining mechanism. XR
Interlocking relay. TOR Train order
relay. POR Power off
relay. LOR Light out
relay. ME Marker
light. OR Overload
relay. GDR Ground detector
relay. CT Code
transmitter. DU
Decoding unit.
Wires Relating To Miscellaneous
Operated Units AK Positive control of
AK. A Positive control of
AR. PC Positive control of
PCR. NLP Positive control of
NLPR. RLP Positive control of
RLPR. R Positive
control of RR. V
Positive control of VR. VS Positive
control of VSR. VP Positive control
of VPR. VY Positive control of
VY. X Positive control
of XR. TO Positive control of
TOR. PO Positive control of
POR. LO Positive control of
LOR. ME Positive control of
ME. O Positive
control of OR. GD Positive control
of GDR. CT Positive control of
CT. DU Positive control of
DU.
This section deals with
symbols used on signal drawings.
Signals and Semaphores (prior to
~1950)
Searchlight and Color Light Signals (prior to
~1950)
Signals, Semaphores, &
Smashboards
Signal Supports
Relays - DC & AC
Relay Contacts
Circuit Controller Contacts -
Miscellaneous
Circuit Controller
Contacts
Contacts Actuated By Switch
Points, Derails, or Locking Connections
Other Signal &
Pneumatic
Indicators, Locks, Buzzers,
& Bells
Other Electrical Schematic
Symbols
Railway Tracks & Highway
Crossings
Buildings, Bridges, &
Tunnels
Wayside Fixtures
Switches
Derails
Miscellaneous Devices Applied
To Tracks
Pipe and Wire Lines
Lead-Outs, Bolt Locks, Cranks,
and Deflecting Bars
