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Specialized Shunt Configurations

Included in this section are special-purpose Shunts or shunt-like products utilizing the traditional head and base of rail clamps.

Unbalanced Track Circuits – Unbalanced track circuits occur on all types of railroads.  Their results can be damaging to shunts on electrified railroadsS&C has configured a unique series of shunts identified by the part number prefixes 550 and 559.   If unbalanced your shunts you will probably want to specify these types.  Substitute the 550 part number prefix for the 506 prefix for standard Clamp Shunts, and 559 prefix  for the 5069 prefix for Clamp Shunts with Strain Reliefs, on any of our Shunt ordering references.

506(XX)RS AC/DC Track Circuit Maintenance Tool

Easy to use tool for maintaining and trouble-shooting AC/DC, Style C Track Circuits.  Our 506-XXRS Circuit Maintenance Tool includes a specified resistance value (usually 0.06 ohms) and zero ohm shunts for making adjustments and testing track circuits for proper train detection.  It also includes a diode to allow you to use the Tool as a substitute diode for determining the source of the failure causing the warning lights and bells to ring without a train present.  Base of rail clamps are recommended for this tool. 

(Insert resistance value .06, .07, .10, .12, .15, .18, .20, .25 where blanks in parenthesis are shown, omitting decimal.  Note that for virtually all freight railroad applications, .06 ohms is the correct value)

506-XXRS Tool with
Base-Of- Rail Clamps
Single resistance & Zero . . 506-(_ _)RSB

506-XXRS Tool with
Head-Of-Rail Clamps
Single resistance & Zero . . 506-(_ _)RSH

506 GCP 4000 (r) Shunt

Designed specifically for calibrating GCP-4000 (r) island circuits. Includes the five resistances required for proper calibration of the island circuit, at the island circuit track wire connections to the rail.  Base of rail clamps are recommended for this shunt.


AShunt, 5 Resistance; .06,.12,.30,.40,.50 Base of Rail Clamps, Bag506-612345BZ
BAbove, but Head of Rail Clamps, Bag506-612345HZ
506-067 Dual-Resistance Shunt for Alstom Circuits

Rugged, traditional, clamp-type shunt for commissioning, adjusting and testing track circuits.  Special resistance combination:  0.06 ohm standard resistance value used for most track circuits and a special 0.07 ohm resistance for accommodating a new Alstom(r) track circuit.  Our unique design assures extremely low probability of resistance variations within the shunt assembly. Switchable between the stated testing values (.06 & 0.07 ohms) and zero ohms with gold test nut switches.

Options include:

  1. Our E-Z On, Base-Of-Rail Clamps, that incorporate a “handle” for shoving the Clamp on to the rail without digging ballast.  Due to the unique angle of attack of the T-Screw, the Clamp will not “walk” off the rail as you tighten it.  And, the unique angle prevents the user from skinning his knuckles against the rail when installing the shunt clamps.
  2. S&C Strain Reliefs for reducing work-hardening and wear where the shunt wires enter the Clamp Connectors
  3. “Open” capability, for opening the Shunt while leaving the clamps in place.
  4. Shunt wire jacket colors:  Black, Safety Orange, Red and Brite Yellow
  5. Heavy duty Shunt Carry Bag, to protect the Shunt while it is being transported.



Black (B) Wire Is furnished unless requested otherwise.  Other choices are Red (R), Safety Orange (A) and Brite Yellow (Y).  To specify optional color add alpha character (R, A and Y) in parenthesis shown below in the ordering reference .  Add “Z” to end of ordering reference to indicate Heavy Duty Shunt Carry Bag




AShunt with 0.06, 0.07 & Zero Ohm Resistances506-067(_)B506-067(_)H
BAbove, but with “Open” capability506-067O(_)B506-067O(_)H
CRef A, but with Strain Reliefs at clamp ends509-067(_)B509-067(_)H
DRef B, but with Strain Reliefs at clamp ends509-067O(_)B509-067O(_)H
516 AC-Only Series Shunts

Used for activation testing of audio overlay and motion-responsive, electronic crossing warning system control circuits and to temporarily block such circuits from being activated by track work within the approaches.  Will not interfere with properly adjusted DC circuits. Cannot be used for adjustment of track circuits.  Well-proven, Probe style shunt is recommended for activation testing because it cannot be forgotten in a condition where it causes problems.  Base of Rail Clamps only recommended if operating circumstances require them.  Also available with Head of Rail Clamps, Web of Rail Clamps, and Warren Fast Shunt Clamps with 14, 24 and 38 inch handles. Please note that out of an abundance of caution, it is the practice of S&C Distribution Company, to call the person to whom an AC-only shunt with rail clamps is being shipped, to ensure that he understands the nature of the product he will be receiving.


Shunt with Probes . . . . . . . . . . . . . . .PN:  516-P

Shunt with Head Clamps . . . . . . . . . .PN:  516-H        

Shunt with Web-of-Rail Clamps . . . . PN:  516-WOR

Shunt w/14 in. Handles . . . . . . . . . . . PN:  506WFS-AC

Shunt w/24 in. Handles . . . . . . . . . . . PN:  506WFS24-AC   

Shunt w/38 in. Handles . . . . . . . . . . . PN:  506WFS38-AC

Shunt with Base of Rail Clamps . . . . .PN:  516-B

518 Combo Shunts

Selectable AC-only, Resistance and Open testing capabilities are offered  by the S&C Combo Shunts.  The Combo Shunt can perform all the normal track circuit adjusting  and test shunting activities performed by signal maintenance and construction personnel.   In addition, in the AC mode, it can be used to check the operation of overlay and motion responsive track circuits without interfering with DC train control circuits, The Open option has been used by railroad signal personnel to create a “dirty” shunt that will cause motion sensitive and constant  warning time devices to go into detection, and is available in the single-resistance configuration.

These Shunts come in several Resistor Block configurations:

  1.  AC-Only, Open, Zero Ohm and one resistor (customer specified from list)
  2. AC-Only, Zero Ohm and two resistors (customer specified from list)
  3. AC-Only, Open and Zero Ohms


We offer these shunts with head, web of rail and imbedded rail clamps, Warren Fast Shunt handles of 24 and 38 inches, and track probes.  They can also be purchased, by special request, with base of rail clamps.  Please note that out of an abundance of caution, it is the practice of S&C Distribution Company, to call the person to whom a Combo Shunt with rail clamps is being shipped, to ensure that he understands the nature of the product he will be receiving.


Specify resistance value desired by replacing parenthesis in ordering reference with value.   Shunt resistances available include 0.06, 0.07, 0.10, 0.12, 0.15, 0.18, 0.20, 0.25, 0.50 and 2.0 Ohms (use “5X & 2X” in ordering references below to signify “0.50 & 2.0” Ohms).


       7-A1Shunt w/AC and Open, Head Clamps518ACO-H
       7-A1AShunt w/AC and Open, Web of Rail Clamps518ACO-WOR
       7-1Shunt w/AC, 1 res., Open & Head Clamps518-( _ _ )O-H
       7-2Shunt, above but with 2 resistances518-( _ _ )-( _ _ )-H
       7-3Shunt w/AC, 1 res., Open & Web Clamps518WOR-( _ _ )O
       7-4Shunt, above, but with 2 resistances518WOR-( _ _ )-( _ _ )
       7-5Shunt w/AC, 1 res., Open & Probes518P-( _ _ )O
       7-6Shunt, above, but with 2 resistances518P-( _ _ )-( _ _ )
       7-7Shunt w/AC, 1 res., Open & Files518F-( _ _ )O
       7-8Shunt, above, but with 2 resistances518F-( _ _ )-( _ _ )
       7-9Shunt w/AC, 1 res., Open & Imbed Clamps518I-( _ _ )O
       7-10Shunt, above, but with 2 resistances518I-( _ _ )-( _ _ )
       7-11Shunt w/AC, 1 res., Open & WFS 38 in hdls518FS38-( _ _ )O
      7-11AShunt w/AC, 1 res., Open & WFS 24 in hdls518FS24-( _ _ )O
       7-12Shunt, above, but with 2 resistances, 38 in. hdls518FS38-( _ _ )-( _ _ )
      7-12AShunt, above, but with 2 resistances, 24 in. hdls518FS24-( _ _ )-( _ _ )
       7-13Shunt w/AC, 1 res.,Open, WFS38  & Meter518FS38S-( _ _ )-OV

Shunt Wire Retro-Fit, w/AC, 1 res. & Open

DO NOT use with base of rail clamps

518-( _ _ )O-1

Shunt Wire Above, but with 2 resistances

DO NOT use with base of rail clamps

518-( _ _ )-( _ _ )-1
506M Multiple Resistance Shunt

Many railroads, particularly those oriented toward passenger transit, have a need for precise track circuit tests and adjustments. Multiple resistance shunts have been developed for this purpose. Most such shunts require various combinations of resistance values to “build” the resistances required.

S&C Distribution Company has simplified the process by supplying the most commonly required range of nine resistances in a protective, easy-access bracket (shown above).  Each of the resistances is individually made active by opening a gold nut test switch.   Values furnished are zero (hardwire), .06, .10, .15, .20, .25, 1.00, 1.20, 1.30 and 1.40 ohms.  Additional resistances can be “built” by opening combinations of switches. An “Open” is also furnished. Additional low-resistance values available as substitutes are 0.12 and 0.18 ohms. We will build this shunt with whatever resistance values meet your needs.  Contact us for details and pricing.



The below ordering references all call for the standard resistance configuration as stated on the first page of this brochure. Any combination of resistances, up to ten is available as a Multi Shunt. Select resistances from the table on the first page of this brochure and contact us for an ordering reference. To specify wire color other than black add the designator to the end of the ordering reference, as follows:  Safety Orange (A); Red (R); Yellow (Y)


DescriptionOrdering Reference
506M Shunt, std Resistances with base-of -rail clamps506M-006B
506MS1 Shunt with base-of -rail clamps, w/Strain Reliefs509M-006B
506MS1 Shunt with head-of-rail clamps506M-006H
506MS1 Shunt with head-of-rail clamps, w/Strain Reliefs5069M-006H
506MS1 Shunt with web-of-rail clamps506M-006W
506MS1 Shunt with imbedded rail clamps506M-006I
506MS1 Shunt with Track Probes506M-006P
506MS1 Shunt with 38 in. Warren Fast Shunt Handles506M-006FS38
Shunt Bag for MS1 Shunt with BOR, HOR Clamps506ZB
Shunt Bag for MS1 Shunt with WOR and Imbedded Rail Clamps, and Track Probes506BZB
Shunt Bag for MS1 Shunt with 38 in. Warren Fast Shunt Handles506ONBZB-38