What is "shackle bar"

Shackle \Shac"kle\, v. t. [imp. & p. p. Shackled; p. pr. & vb. n. Shackling.]

1. To tie or confine the limbs of, so as to prevent free motion; to bind with shackles; to fetter; to chain.

   To lead him shackled, and exposed to scorn Of gathering crowds, the Britons' boasted chief.
   --J. Philips.

2. Figuratively: To bind or confine so as to prevent or embarrass action; to impede; to cumber.

   Shackled by her devotion to the king, she seldom could pursue that object.
   --Walpole.

3. To join by a link or chain, as railroad cars. [U. S.]

   Shackle bar, the coupling between a locomotive and its tender. [U.S.]

   Shackle bolt, a shackle.
   --Sir W. Scott.