This was shot in the yard up at Silver Plume…so, uh…what are they?
I’m guessing some sort of brake part, but I’m not certain and I’d like to know before I label it wrong on the Flickr page. [;)]
Thanks in advance!
They look like old cast iron brake shoes for ore cars or jennies…note the one shoe about middle of the image that is worn.
^^^ What he said . . . Compare with the one at the lower left, which is much thicker and a more uniform rust color, whihc means it’s likely new/ never been used. Also, note the lugs and indents on the back to seat them in the brake beam and for the retainer key to hold them there.
Historically, I believe that cast iron was the preferred material for brakeshoes at least until the 1960’s, when the composites started being manufactured and placed into service - now, I believe those dominate the market.
These happen to be break shoes. They are fitted onto the wheel’s of railcars and locomotives. They come into contact with the wheel once the engineer makes a break reduction. Correct me if I’m wrong.
-Justin
Here’s a link to a 1981 - 1984 patent for a “Railroad Brake Shoe-Brake Beam Assembly” - the drawings illustrate a lot:
http://www.freepatentsonline.com/4466513.pdf
- Paul North.
Ah ha! Thanks for the input guys. I was thinking brake shoes, but I was confused that they seemed to be all iron instead of composite (which was all I could remember seeing previously). I didn’t realize that cast iron was used. It seems like it’d be really hard for wheel wear?
Paul,
Couple of things, the smaller size and the presence of the big lug with the bolt hole.
Normal brake shoes for standard railcars are held in place by a long thin key, not a bolt, to facilitate quick change out.
And most of the smaller MOW equipment we have on the PTRA use shoes that look a lot like these, except they are composite not cast iron.
I believe there are a few iron ore roads up north that still use cast iron shoes like this, their cars are in captured service, mine to dumper and mine to dock…some one from iron country will most likely know more.
[quote user=“Paul_D_North_Jr”]
^^^ What he said . . . Compare with the one at the lower left, which is much thicker and a more uniform rust color, whihc means it’s likely new/ never been used. Also, note the lugs and indents on the back to seat them in the brake beam and for the retainer key to hold them there.
Historically, I believe that cast iron was the preferred material for brakeshoes
Don’t feel too bad, Chris–I would have been taken aback by brake shoes being attached that way, too. That’s a lot of work for a changeout there (admittedly probably not as often). I believe that some freight cars today specify steel brake shoes instead of composite, for whatever reason–but the changeout, when necessary, is accomplished by carmen after the train is made up and on the departure track–it’s that fast.
Thanks, Ed. The MOW equipment brake shoes should have occurred to me - but it’s been quite a few years since I helped change any of those. Besides, the mainline carmen would call those ‘baby’ brake shoes . . . . [swg]
Here’ a long link to a short - 1-page or so - section 7.10 on Brake Shoe Type and Friction on pp. 121 - 122 in Train accident reconstruction and FELA and railroad litigation - there’s a pretty good amount of info there, including why the modern ones are commonly referrred to as ‘‘COBRA’’:
This 2003 article from the International Railway Journal is also technically interesting
Chris,
Cast iron is quite soft compared to steel, and they carry away a lot of heat, up to a point.
Cast iron can only radiate so much heat away, composites radiate more per square inch.
Composites also create more “friction” per square inch.
Your automobile has a composite brake pad, part composite materials and steel mixed, the “metallic” brake pad most car makers have specified since around 2000.
The metal helps transfer heat, the composites provide more friction.
Cast iron rail shoes tend to wear smooth and become ineffective, and as they heat up and become even softer, they also lose a lot of the friction needed to stop the wheel.
Composites tend to stay more “rough” with more of the friction surface exposed, they last longer and don’t tend to fade as cast iron shoe do.
Cast iron is still used in many industrial brake applications, from heavy machine lathes and mills, tools like that.
If memory serves me, the only ore car/jenny I in person saw had the shoes mounted with a clevis pin, washers and a big cotter pin, looked like it would be almost as fast a change out as today’s set up.
Hopefully someone out there has a photo of a ore car we can look at and make sure…
The compositionshoe has a downside when the temperature dips way below zero and even worse if you have snow blowing around under the train, It takes forever to get the shoe warmed up enough to down some effective braking. The blowing snow acts as a heat sink that draws too much heat away.
On the Soo in North Dakota we had some wild three to four mile stopping distances from 30-40 mph on basically level track. Did not have that problem when we had cast iron shoes on about half of the train consists…
Under normal conditions the composition shoe is an improvement, that greatly reduces wheel wear and shoe change intervals.
Now that the original question has been answered I would only add…“THE ONLY DUMB QUESTION IS THE ONE YOU DON’T ASK!”.
Again, many thanks to all for the information!