Bob, thanks very much for this! Mystery solved. And thanks to all who responded. 

-----Original Message-----
From: HISTORICAL ARCHAEOLOGY [mailto:[log in to unmask]] On Behalf Of Bob Skiles
Sent: Wednesday, July 19, 2017 6:25 PM
To: [log in to unmask]
Subject: Re: Railroad hardware

Before the advent of modern welded rails, sections of rails were joined together with "joint bars" fastened with large bolts and nuts. "Tail lock nuts" were an early form of what might now be most commonly called "lock washers." They were used to try an obviate the constant problem of the nuts loosening on the track bolts. Without locknuts, the vibration from passing trains would inevitably cause loosening of the nuts on the track bolts. Before the common adoption of locknuts (ca 1900) inspecting for, and re-tightening of, loosened nuts was a constant, frequent and costly task for railroad trackmen. There were a variety of differing forms of locknuts introduced in the 1900s in an attempt to obviate this expense (not to mention the risks from having loose nuts). The "tail" 
lock nut was but one form which was adopted; the object of the "tail" 
was that it would protrude into the joint between two rail sections and thus stop the rotation of the nut which had it clamped and fixed into place on the bolt.

Railroad inspectors reports from ca 1910-1920s are replete with a most common complaint of finding "loosened nuts on track bolts" and recommendations that some form of locking nut be installed; it was not until after WWI that locking nuts had become rather universally employed by most railroads. Many smaller railroads never adopted them, and kept-up their age-old maintenance routine of sending trackmen over the line (daily) to find and tighten nuts.


On 7/19/2017 9:38 AM, Joseph Howell wrote:
> Hello HISTARCH folks,
>
> I am trying identify these metal objects found along an abandoned portion of the Southern Pacific RR. A fairly extensive search has turned up nothing, other than other people who don't know what they are either. We found quite a few of them, usually in association with crosstie plates, rail anchors, and spikes. I'm thinking they are some kind of lock washer. Anyone?
>
> https://drive.google.com/open?id=0B4GzvIWsfmnCUUZGblE1ZUNMb1E
> https://drive.google.com/open?id=0B4GzvIWsfmnCb1BndTJ5RkNXYlE
>
> Thanks!
>
>
> Joseph Howell
> Archaeologist
> Statistical Research, Inc.
> 6099 E. Speedway Boulevard
> Tucson, AZ  85712
> Phone: (520) 721-4309
>
>
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