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Mr. Sandman

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Mr. Sandman
Posted by Murphy Siding on Tuesday, September 4, 2007 9:27 PM
     Can someone explain some of the finer points of sanding the track?  I understand how sand can increase adhesion of a steel wheel to a steel rail.   Is it blown on, or simply dropped out of a tube?  Does each drive wheel get a tube?  Since locomotives operate in both directions,is there a sanding tube in front of, and behind each wheel?  Is there different sand used for different areas?  I've read that the sand is usually off the track, by the time the first freight car wheels hit the spot that was sanded.  If sand on the track where it's not needed adds to the rolling resistance of  wheels on freight cars, does blowing, desert sand cause problems on track?  Does all that sand being put down cause track problems?  Is Horseshoe Curve knee deep in sand?   Anyone?  -Thanks

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Posted by tree68 on Wednesday, September 5, 2007 11:44 AM

Based on my limited knowledge:

Sand nowadays has help (air).  In the early days it might have been gravity fed - note that the sandbox is on top of the boiler on steam locomotives, which may have also helped keep it dry.

Sanders are directional - on current locomotives I think the change is automatic depending on how the reverser is set.  I'm not so sure I've ever noticed sanding tubes behind the drivers on a steam locomotive, though.  Most were generally expected to move primarily in one direction.

Some steam locomotives had steam jets behind the drivers to blow any remaining sand off the track, due to the increased rolling resistance offered by the sand.

Don't know about desert sand, although I have seen pictures of sand being plowed off the tracks with a snowplow during the days of the Dust Bowl.

Many grades have a lot of sand on them - I've seen pictures of some where the use of sand was obvious just by looking at the roadbed.

Mudchicken will have to speak to problems that the sand can cause in the roadbed itself.

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Posted by CopCarSS on Wednesday, September 5, 2007 11:59 AM

 tree68 wrote:
Sand nowadays has help (air).  In the early days it might have been gravity fed - note that the sandbox is on top of the boiler on steam locomotives, which may have also helped keep it dry.

I know in some areas of the world, sand can even be applied by hand. I seem to recall a documentary (on Indian Railroads perhaps?) that featured train crewmembers sanding the rails around the locomotive wheels and on the rails in front of the locomotive.

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Posted by edblysard on Wednesday, September 5, 2007 1:21 PM

Murphy,

Sand is delivered by a tube to the leading wheel on the leading truck, depending on which way the reverser is set...compressed air from the main reservoir is used to blow the sand onto the rails, although gravity feed has also been combined with compressed air on older models.

As for removing the sand after the locomotive passes, the weight of the locomotive makes that a moot point, what's left on the rails is ground as fine as talc...removal is not a necessity, and unless the engineer manually sanded the rails and gets carried away, the amount left makes no real difference.

It works the way you surmised, the sharp edges of the sand "cut" and grip the steel in both the wheel and rail, providing a "rougher" texture or more grip and traction.

 

Most new locomotives use the wheel slip computer chip to activate the sanders, but there is a switch where the engineer can sand at will.

And you can always tell when he sat still for a while, but forgot to turn off the sanders....the little piles of sand on the sides of the rails gives it away.

 

Most carriers rule books prohibit using the sanders over switches and frogs, for the obvious reason it gums up switches.

 

They don't use ordinary play ground sand, but buy finer sand that has been washed and screened, quite like the sand a metal caster would use for his moulds.

Most engine service areas have a large overhead sand rack, the supplier dries the sand, and then delivers by hopper truck most of the time, but older facilities sometimes have their own dryer system and get sand delivered by rail in a covered hopper.

 

 

 

In the above photo of a GM export locomotive, the sand boxes are the square boxes directly in front of and behind the leading wheels on the trucks, and they use gravity feed.

 

Here you can see the sanding tubes...they are the long "hoses" that come out of the under frame and curl around, ending at the inside wheels nearest the fuel tank...there are corresponding tubes for the front wheels on each truck also, if you look under the front steps, you can just see one of them.

Depending of how the reverser is set, this locomotive will sand ahead of whichever wheel is a "leading" wheel.

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Posted by spokyone on Wednesday, September 5, 2007 8:21 PM

Thanks a lot Ed. Great explanation with pictures. Now we know.

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Posted by Dakguy201 on Thursday, September 6, 2007 4:17 AM

A little off topic, but this is supposed to be the last of the wooden sand towers.  It is located on the grounds of the Milwaukee roundhouse in Sioux City Ia.

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Posted by egmurphy on Thursday, September 6, 2007 8:59 AM

I'm not so sure I've ever noticed sanding tubes behind the drivers on a steam locomotive, though.

Just to add something to this one point, having sand tubes behind the drivers was actually a common practice, at least on steam locomotives that would see service in switching or way freight service.

It was also common to see two sandboxes on steam locomotives, one up front and one behind the steam dome.

Best regards

Ed

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Posted by Murphy Siding on Thursday, September 6, 2007 9:53 PM
     Thanks from me as well, Ed B.  Any thoughts on whether unwanted sand on the tracks is an issue, as far as adding too much friction to the equation?

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Posted by J. Edgar on Thursday, September 6, 2007 10:07 PM
 egmurphy wrote:

I'm not so sure I've ever noticed sanding tubes behind the drivers on a steam locomotive, though.

Just to add something to this one point, having sand tubes behind the drivers was actually a common practice, at least on steam locomotives that would see service in switching or way freight service.

It was also common to see two sandboxes on steam locomotives, one up front and one behind the steam dome.

Best regards

Ed

most experinced hoggers would sand the rails backing up to couple their train....this would leave a good coating to start off......even good modern engineers( ya hear me Bob) would do this to start a heavy/underpowered train
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Posted by J. Edgar on Thursday, September 6, 2007 10:12 PM
and no Horseshoe is not knee deep in sand.....but if you look at older steam era pics from places like that....or Sandpatch...or anyplace that had a stiff grade and multiple tracks.....you could always tell the uphill track by the color of the  ballast....its sand colored  Wink [;)]
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Posted by edblysard on Thursday, September 6, 2007 10:36 PM

For the most part it makes no real difference...our locomotives have "automatic" sanders hooked to the wheel slip computer, and when we are flat switching, and the engineer is going from idle to run 5 or 6 the system often detects the small amount of wheel slip and sands the rails...after the first pass by the locomotive, the sand is pretty much gone.

Keep in mind these things are not blowing a large amount of sand in the first place, and the sand is very fine...if you were to put your hand under the sander while it was on, it would take several seconds for you to have enough sand in your hand to make a fist around.

There just isn't that much being applied and it only requires a small amount to accomplish the job.

As for excess sand on the rails, say from a unit that was in manual sanding mode and sat still for a while, it still makes little difference once the engine and a few cars have passed over the sand, most is just pushed out of the way by the locomotive wheels, and the amount that gets between the railhead and wheel is crushed and gone quite quickly.

 

Now, hitting a large pile at speed might cause a few bumps in the ride, but again, it is gone by the second or third car, reduced to a fine powder that causes no traction problems or extra resistance to the following cars.

 

Our MOW guys make small crossings for the car men to drive their scooters over the tracks by dumping and tamping asphalt between and around the rails, often above the ball of the rail, and we run our locomotive over it when they are done to create flange ways...the excess is pushed out of the way, and the wheels cut nice neat flange ways...although sometimes a small amount of the asphalt will stick to the wheel tread and you have to listen to the bump bump bump sound for a few minutes.

 Murphy Siding wrote:
     Thanks from me as well, Ed B.  Any thoughts on whether unwanted sand on the tracks is an issue, as far as adding too much friction to the equation?

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