Flat Wheels

Pardon my ignorance, but what exactly is this term "flat wheel"? Do steel wheels actually develop flat spots or is this just a term meaning that the wheel slides along the track without turning with no physical consequence? And if it does develop a flat spot, can we actually hear one on a passing train?

Right on. Wheels slide and grind against the rail, making flatspots. You can certainly hear them...especially on this video:
http://www.youtube.com/watch?v=cWzL2j7m8-s

And as most of us know, this is the season for flat spots, especially today, with the rain and falling leaves. My train last night out of Huntington caught the first of the rain showers for the night. This is when the tracks are at it's worst. Our M-7 kept sliding everywhere both when coming to a stop and while attempting to accelarate out of stations. When all was said and done, we had a few flat spots on our train. A flat wheel simply makes a very loud thumping noise, typically because the wheel lost it's perfect circular shape by having a wheel lock in place and sliding.

For some extra reading, try "Rolokron" in google.

Wow! I never realized that this was such a problem! This now explains the thumping sound of some freight car wheels out here in St. Louis while waiting at railroad crossings.

I can't figure out how a smooth edge of the wheel can go flat while slipping/sliding on the smooth surface of the rail. Logic would tell me that at least one surface would have to be rough to act like a grinder, but then again I don't know the physics surrounding this. I can only assume that the weight on the sliding wheels is one factor that plays a part in this. I'm sure there are others.

Flat wheels are a huge problem in mountainous regions of the country, because of the heavy breaking when going down sharp grades.

frankie wrote:Wow! I never realized that this was such a problem! This now explains the thumping sound of some freight car wheels out here in St. Louis while waiting at railroad crossings.

I can't figure out how a smooth edge of the wheel can go flat while slipping/sliding on the smooth surface of the rail. Logic would tell me that at least one surface would have to be rough to act like a grinder, but then again I don't know the physics surrounding this. I can only assume that the weight on the sliding wheels is one factor that plays a part in this. I'm sure there are others.

Very easy Frankie the sliding wheel heats up to point of liquefying a small spot of wheel where it slides on the rail, once a spot like that exceeds 2 1/2 inch the car or locomotive is condemnable, and has to go to shop or have wheel exchanged in nearest siding/spur, moving a locomotive or car with spots bigger must be moved at very low speeds to avoid shattering wheel or braking rail due to impact.

the opposite event is true for a stalled locomotive causing rail burns.

Flat wheels on locomotives are a much bigger problem than on cars. Several years back, when the Rio Grande was still with us, a Utah Railway hogger took his 300 series lash-up (RSD4-5's) with a flat spot on one unit out on the Rio Grande main. As you may know Utah Railway has trackage rights over Soldier Summit (used to be Rio Grande, but now UP). But back to our story; the Rio Grande was so concerned and hacked with this, that they closed the main affected until the Sperry car could check it, and the hogger in question was banned from the Rio Grande main permanently.

There must be more to story as the FRA and railroad rules normaly are same on 2 1/2 inch rule, so mauybe this guy took the 2 1/2 inch to a extreme and caused a uproar.

A flat wheel, if rolled fast enough and if the weather is cold enough, can break the rail. Many flat wheels are caused by the brakes not releasing on certain cars in the train. Minimum reductions in very cold weather is a culprit.

On locomotives, flat wheels were caused by cast iron brake shoes when making too heavy a independant brake application, causing the wheels to actually slide. This was a problem on BN SD9 locos in the Alliance, NE yards.

DutchRailnut wrote:There must be more to story as the FRA and railroad rules normaly are same on 2 1/2 inch rule, so mauybe this guy took the 2 1/2 inch to a extreme and caused a uproar.

As I understand it, it was a severe flat spot which he took over the whole 60 miles from Martin to Provo.

I guarantee the severe flat spot was NOT on the unit he was riding, LOL!

I had an IC SD70 a few weeks ago that had pretty good flat spots on the #1 & #2 axles, they were so loud at 60 that I literally got a headache.

I "heard" that when one switches cars with hand brakes left on, especially when the cars are empty, that the wheels skid and cause flat spots ...

gp9:

Very true.