IBLS Coupler and Safety Chain Standards

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Layout

Couple and Safety Chain Layout
ScaleGaugeCouple Height (CH)Chain Offset (CO)Link SizeChain Length
3/4"3-1/2"2-1/4
1"4-3/4"2-7/8"
1-1/2"7-1/4"4-7/16" +0" -3/16"2-1/2" +/- 1/4"1/8"x1" welded6" +/- 1"
1-1/2"7-1/2"4-7/16" +0" -3/16"2-1/2" +/- 1/4"1/8"x1" welded6" +/- 1"
1.6"7-1/2"4-7/16" +0 -3/16"2-1/2" +/- 1/4"1/8"x1" welded6" +/- 1"
  • Safety Chain Data
    • Right hook is a captive hook
    • Left hook is an open hook

Tidbits From Chaski

From http://www.chaski.com/homemachinist

ccvstmr

ILS standard calls for two (2) 1/4" hooks at 2.5" distance from the centerline of the car. I set the hooks at 3" because I don't like to "crowd" the coupler. Eyebolts with 1/4x20 thread and various length shanks can be purchased at most hardware stores. The left hook is twisted open while the right hook is opened...the chain inserted...and the hook closed to make the chain captive. Chains are 6" +/- 1". Chain material is 1/8" x 1" welded link...although 3/16" x 1" link would also do. The chain must fit over the chain hooks. Wire-wrap chain is not acceptable either.
One point that is often overlooked...is the method in which the the chain hooks are attached to the loco/car body. A screw-in eyebolt hook is not acceptable, nor is a hook attached to an endsill that is nailed to the end of the car. In other words, the hook attachment to the car body must be strong enough to withstand the forces transmitted through the chain(s) during a derailment. It is better to destroy the hook (straighten it out) instead of destroying your rolling stock or let your cars get away and be stopped by the next train that follows.
Another item to watch for...always make sure that safety chains are hooked at both ends...even if it's the last car of the train. A dragging chain will easily catch a turnout frog and/or heel block if you're not careful. The result...time to replace the chain hooks. Hope this helps.
Coupler height...most clubs have coupler height specs. Some follow IBLS, others are not far away. Usually the center of the coupler is set 4-1/4" to 4-7/16" over the rail head. Of course, as long as "out of spec" equipment is not coupled or run with "in spec" equipment, there's no problem. However, if the couplers have excess vertical motion, this is where a problem can start.

ehulshiz

At Train Mountain they do it much as described above, but they use closed eyes and threaded chain "repair links" (you know the ones).

References