View source for Signal Joining Rings

== Overview ==
Signal joining rings are known by different names depending on the signal equipment manufacturer.  The most common trade name might be carriage ring or tri-bolt washer.  [Insert some other names from various manufacturers.]  All of these names and hardware are interchangeable.  Brought about during the post WWII advent of modular, closed body signal construction, these are the unified flat washers that, along with typically three carriage bolts, join two traffic signal aspects together via the unused pipe mount bosses.  This replaced the much less adaptive, sealed, or repairable design of open body signal sections held together with a single set of endplates and tie-rods.  When the modular body sections were keyed for serrated locking rings on both top and bottom of the signal aspect it was also possible to create “twisted” signal designs wherein each lens does not need to point in the same direction, they are free to rotate 360° about the mounting axis.
== Exceptions ==
There were a few notable exceptions to the use of carriage rings in closed body signal construction.  

=== Marbelite ===
Most notably is the earlier body styles of Marbelite signals.  Despite having the typical pipe boss and capable of using a tri-bolt ring the castings were molded with three drill out reliefs near the outer extremities of the signal.  To assemble, one drilled these three holes on each signal, stacked them, then bolted them together with a bolt and square washer.  While an elegant approach, and one could say more reliable, it was eventually eliminated for the common carriage ring design.

=== Crouse-Hinds ===
Another, rarer bird, is the rodded CH Type M (Breadpan.)  For city specific requirements, this signal was constructed conventionally (with the tri-bolt washer) but available with each body section drilled and rods inserted through them all creating a belt-and-suspenders approach.  This was perhaps less of a Luddite approach than it seemed.  The Type-M body design did not have any serrations or other keying features on the top of the signal section, only the bottom.  When stacking them, it was only the alignment and tightness of the bolts that would retain a signal aspect from rotation.

=== Visual Identification Guide ===
{|
|-[[Image:CarriageRing_GEStreamline.jpg|200px|link=#Marbelite]]
|}

<gallery>

File:CarriageRing_GEStreamline.jpg|Caption1
File:CarriageRing_GEStreamline.jpg|Caption1
File:CarriageRing_GEStreamline.jpg|Caption1
</gallery>

File:CarriageRing_GEStreamline.jpg|Caption1

CarriageRing_RCHDOH.jpg
CarriageRing_RCHSOH.jpg
CarriageRing_RCHSOHLG.jpg
CarriageRing_Mickey.jpg
CarriageRing_MickeyClip.jpg
CarriageRing_3MRound.jpg
CarriageRing_Poly1.jpg
CarriageRing_3MClip.jpg
CarriageRing_Delta.jpg
CarriageRing_SiemensEuro.jpg
CarriageRing_GECan1.jpg
CarriageRing_GECan2.jpg
CarriageRing_MickeySmall.jpg
CarriageRing_Rad.jpg
CarriageRing_Pelco.jpg*