# Clump - clump - clump



## SD90WLMT (Feb 16, 2010)

What goes 'clump clump' on a big diesel loco?


Just saw a pair of locos, on a by-run / light power move towards Tucson ..

A SD40N, #1641 - towing a SD60 wide cab down the line......

doesn't sound too good either... thought they just went by on the rear of a freight too ...

Clump - clump - clump, something off, bearings maybe, loud enough for me to hear it 1/4 mile away...

Running like maybe 2 mph is all, a very long, slow trip,.. back to the barn....

Broken again....

Any body got an idea...?

Dirk


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## Semper Vaporo (Jan 2, 2008)

It is was running slow because of a problem then I would suspect it has a flat wheel and it is so bad that it must be moved very slowly to prevent damage to not only the rest of the loco but the track as well. A Loco (or any loaded full car) can do serious damage to the track if it has a flat spot on the wheel. I suspect the brakes locked up and it slid and wore a flat spot.


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## Scottychaos (Jan 2, 2008)

Most likely a "flat spot" on a wheel, or several wheels..somewhat common issue.
If a train needs to brake hard for whatever reason, the wheels can lock-up and "slide" on the rail,
which results in a small flat spot on the wheel..then when the wheel turns, you get a loud "clump" with each wheel revolution.
The wheels are swapped out as soon as possible, when the car (or locomotive) is shopped, but for a little while a car will operate with the flat wheels
before it can get to the shop..

Flat spot video


Scot


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## pete (Jan 2, 2008)

We live close to train tracks and hear that same sound I just though it was bad bearings. I retired the Timken company the department I worked in we would get r r bearings that were so torn up the rollers in them were crushed.


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## pete (Jan 2, 2008)

Sorry it should read I retired from the Timken company.


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## SD90WLMT (Feb 16, 2010)

As locos are in excess of 415,000 pounds, I could almost ''feeeeel'' the clump, clumps, .. besides just hearing them. 

Flat spots it is then,... 

As for cars - with a siding here in Dragoon, bad order cars do get set-out on occasion for repairs. Recently the last set-out was just for an axle change.. couple trucks showed up, and several crew, - lifted the car in the air & rolled the bad truck out from under it, then lifted the truck on one end and rolled the bad axle/wheel set out from under that also, placed a new axle back under, back under the car and off - they were gone.. to the next job... 

Dirk, DMRR


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