Steam Locomotive Slipping The Wheels

Well THAT sure doesn't make any sense. Why would steam be connected to the locomotive's sand application traps, as air pressure is used to apply traction assist sand.  Air pressure is dry and steam is wet, and would quickly clog up the sand traps from the condensation.

Hot Water, many British locomotives use a steam powered sanding system. 

Below is a diagram of the basic system, and here is a some history of the system.

Well, to each his own, I guess. From an engineering standpoint, that sure sounds illogical to me, as the steam will be pre-wetting the sand and causing it to act more as a lubricant than an adhesion improver. 

Now, something else occurs to me; if those steam jets in front of the drive wheels are indeed truly applying sand, then why is the Engine Driver applying sand while the drivers are still slipping? THAT is an absolute NO-NO, at least on steam locomotives in the U.S., Canada, and South Africa!!!!

That explanation is a little suspect, too. The article claims Wstinghouse didn't think using air was a good idea for safety reasons; however, by that time, straight air wasn't used. If air pressure got too low in the system, it would apply the brakes. That sure doesn't sound terreibly unsafe.

I haven't worked with vacuum brakes in quite some time (28LAV, which uses a compressor exhauster on a diesel electric locomotive, but I don't think the 2-6-4T BR locomotive has a compressor, the locomotive is equipped with vacuum brakes.

Even an automatic vacuum brake system, which came in towards the end of the 19th century, there is no need for compressed air.  Here is a link that describes the operation of an automatic vacuum brake system. 

http://mikes.railhistory.railfan.net/r143.html

I think the only reason why steam was used on the sanding system is there isn't any compressed air available.  Bizarre, and like Hot said, goes against everything that we were ever taught about locomotive sanding systems. 

I went looking for more information on the 80 class steam locomotives to see if I could confirm it, but couldn't find anything that talked about the brake system.  Here is a link to the BR Class 4 2-6-4T loco.

http://en.wikipedia.org/wiki/B...ndard_Class_4_2-6-4T

Regards,

Jerry

quote:

many British locomotives use a steam powered sanding system.

Well, I hear there are plenty of seats available at the College of Common Sense!

Steam-powered sanders? Hmmm...

I can't imagine that working very well starting out on a cold, damp morning when the steam is still very "wet."

Can you say, "Plugged sanders?"

In a steam sander, the steam doesn't blow directly onto the sand, but is blown through a cone so as to create a vacuum that sucks a sand/air mixture down from the sand reservoir. The sand only meets the steam very shortly before it reaches the rails.

The system works very well, and was used in steam engines right until the end. I believe that 'Tornado' was built with this system too.

Here is another diagram of the system, and a description from a much more authoritative  book.

Below is a photograph and a little more information from the same book.

OK, so we have established that the British use steam sanders.

But,,,,,,,,that still does not explain why the Engine Driver had the sanders obviously on full, while the drive wheels were STILL SLIPPING!!!

This from my friend in England;

"The sand boxes on British engines are between the frames.  Steam is not wet until it condenses and the action of blasting the sand out with steam gets rid of any gunge on the rail head as well as delivering the sand.  A few years ago there were problems with modern diesels and electrics in autumn as the air powered sanders would not clear the leaf slime resulting in trains slipping to a halt."

and

"that hill out of Exeter was quite famous as it was between the two stations.  A class of 0-8-0 tank engines (Z) were kept there to push trains out of the lower station."

Nicole, thanks for your explanation.  I had wondered, from the initial diagram, just how the sand was forced down. 

With steam blasting the sand from the pipe, I wonder how much sand is actually staying on the railhead!

Makes for an interesting Pro/Con discussion. If you could take out the "blasting" and put in "laying down", it would be even more interesting.

What at first glance seems counter-intuitive, could in fact have some redeeming value.

When sanders "blast" out the sand on dry rail, how much of it stays on the railhead? I'm sure most of those grains of sand bounce and get blown right off the rail. A wet rail could allow more sand to actually stick to the railhead, but, then you have the "wet factor".

I can also understand the reasoning behind having the steam jet clear off the "leaf laden" railhead (witness O. Winston Link's "Mockingbird" recording). However, I think it would have been much better to have a steam jet facing forward that could clean the rails of leaves and such, then lay down the sand behind.

A sanding system that could accurately "Lay" down a stream of sand would be best and less wasteful.

It has been my experience that if the rail is going to be wet, a good hard rain is much much better for traction than anything else. A good hard rain will tend to wash away oils that have found their way onto the railhead. A lite rain will not do that and tends to compound the "slick" factor. Frost is the slipperiest think out there (other than a thin line of oil that the MoW crews put down on the railhead instead of the ball of the rail where it was supposed to go). Frost will stall a train faster than anything.

Interesting, sand can make the difference of getting over the grade or doubling. Tent caterpillars were also  a problem here (ontario) every so many years . I can't remember if  all the units applied sand or just the leading one. Jim?

That would depend on whether the Engineer used the "train lined sanding" function, or simply switched on the "lead axle sand" only toggle switch.

In the steam sander, the stream of sand is directed directly to the point where the rail meets the wheel. This way you don't have to rely on the sand staying on the rail, and it also saves a lot of sand from being wasted. 

Unfortunately, for the most part in today's world, train line sanding only works when the speed gets down below about 12mph. Worse still, the newest units will not even allow you to use lead axle sand until you get down that low. That's just the way they are programmed. Someone out there in the dark (you know where) thinks they know better than any engineer when sand will be needed!

If the rail is so slick that it has caused you to stall, one course of action is to cut the units off from the train and sand the rail over the top of the mountain. In order to get the maximum amount of sand on the rail you have to creep along at about 10mph so that all of the sanders will be working. Usually, you can then pull away pretty easily. If it happens to be raining very hard, all of that good sand gets washed away. Then you are probably going to have to double the hill.

If any of you have ever watched NHRA Drag Racing, you have heard of "overpowering the track", culminating in some violent wheel hop. The same basic thing can happen on the rails. The 8th notch can be too much power for the track conditions to handle causing some violent wheel slipping. Many a time I have simply eased off to the 6th notch in order to get over a mountain.

Nicole,

That is way it is supposed to work, but again, it doesn't always work that way. I'm certain there is an amount of that sand that gets caught up in the eddys of steam and never see the rail.

Steam-powered sanders...how about that. I learned something new today.

Thanks, Nicole.

The 8th notch can be too much power for the track conditions to handle causing some violent wheel slipping. Many a time I have simply eased off to the 6th notch in order to get over a mountain.

Yep!   I worked an ore train for a few years....  5 GP 40s all on the head end  and about 80 cars.... around 14 thousand tons.

 I've changed a few  knuckles. One little slip and ....  broken knuckle . usually about 5 cars behind the engines.  

Worst trip ever... 2 knuckles and and  draw bar all at once in the middle of winter and about 10 below...

One thing about Railroading... You learn something new just about every day even after retiring

Ive heard of railroads having rail grinding cars,

but that's ridiculous.

Maybe he should backoff on the throttle and use his sanders or was he retruing the driving wheels.