Sand as a Last Resort?

[wheelnrail]

After some time observing train operations here in all types of weather (except heavy snow), to me at least, it seems that if conditions are less than ideal and adhesion is not good, you don't use sand unless absolutely necessary. Obviously if you controll the power to the wheels the need is reduced or eliminated but in extreme cases (61306 at Gloucester this year) sand is held off until there's no other way to get going. Could it be a cost factor for sand? Or am I totally wrong?

I ask because in the states we're use to seeing trains utilize sand to get going, and I rarely if ever see it here.

 

[RPM]

Sand isn't actually a big expense. If I need sand to get moving then I'll use it. Braking is different because sanding is automatic on the units I drive, but if it wasn't then I'd apply it as necessary. It's sand not diamond dust.

 

[edwin_m]

Just to clarify the above, sand is only dispensed on braking if the wheelslide protection system detects poor adhesion, so it is not used indiscriminately. There have been concerns about too much sand insulating trains from track circuits, but I think that has been largely dealt with. There is probably someone somewhere in Network Rail worrying about the extra ballast cleaning too.

 

[SPADTrap]

On the units I drive sanding is manually applied on acceleration with a push button in the cab which can provide sand in up to 10 second bursts, this needs a few seconds pause between presses to let the sand move about in the sander box to 'refill' as far as I'm aware. Sand for braking is automatic in brake steps 2 and 3 and emergency, as edwin_m stated if the system detects a slide then it will apply sand. I don't know the expense of sand as the shunters refill the sanders and we have no interaction with the sanders in that respect beyond making sure its locked shut on prep but it is there to be used and to get the train going quicker and more efficiently than without to minimise delays. If you can get away with slightly reducing the power then try that first before lazily emptying sand, another driver may well need it to assist in stopping and if you've emptied it unnecessarily and the unit hasn't visited the depot to have it refilled it could cause them a headache.

 

[Taunton]

There have been occasional instances with steam locomotives of sanded rails causing the buckling of coupling rods, so you can maybe understand the reluctance of private owners to use it unless essential.

Some steam designs of the past used steam-assisted sanders, which blasted the sand jet directly at the wheel contact point; late Victorian single-wheel driving locos particularly used this to ensure they could get away in wet conditions, although introducing wet steam around sand which will clog if wet introduced its own potential problems. Large US steam locomotives used air-assisted sanders as they had compressors for air brakes, but UK steam locos, almost all vacuum braked, did not have this. Steam sanding seemed to die away later in the development of steam power.

 

[Deepgreen]

There have been occasional instances with steam locomotives of sanded rails causing the buckling of coupling rods, so you can maybe understand the reluctance of private owners to use it unless essential.

Interesting - how does sanding cause this? I've heard of uncontrolled wheel slip causing damage, but not sanded rails.

 

[plastictaffy]

Wheels already spinning, with sand arresting it, and all the sudden torque bending the rods rather than applying traction, at a guess.........??

 

[talltim]

Sand is cheap, the cost of someone filling the sanders is not. Also the sand reservoirs are not huge, so you/the computer uses as little as possible so you don't run out later.
This RAIB report gives some interesting information about both sanding and sander refill procedures https://www.gov.uk/government/uploa...data/file/411020/111117_R182011_Stonegate.pdf
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Wheels already spinning, with sand arresting it, and all the sudden torque bending the rods rather than applying traction, at a guess.........??

Or some wheels trying to spin, while others are gripping?

 

[Taunton]

You will need to ask an old-time mechanical engineer how the rods can be buckled with sand usage, but my own guess would indeed be the oscillation between slipping and grip.

Author David L Smith, who wrote at length and in detail about loco issues on the old G&SW in Scotland, related a discussion between a driver and Hugh Smellie, their Victorian and authoritarian Chief Mechanical Engineer, about a loco having wheelslip with the steam shut off and bending the coupling rods. Smellie wouldn't believe it, but Smith, without elaborating, said that this showed Smellie didn't know everything about locomotives. I have always wondered how this can happen as well.

 

[Deepgreen]

You will need to ask an old-time mechanical engineer how the rods can be buckled with sand usage, but my own guess would indeed be the oscillation between slipping and grip.

Author David L Smith, who wrote at length and in detail about loco issues on the old G&SW in Scotland, related a discussion between a driver and Hugh Smellie, their Victorian and authoritarian Chief Mechanical Engineer, about a loco having wheelslip with the steam shut off and bending the coupling rods. Smellie wouldn't believe it, but Smith, without elaborating, said that this showed Smellie didn't know everything about locomotives. I have always wondered how this can happen as well.

While I don't have the intricate technical knowledge to deny this, I would imagine that the risk of damage from heavy slipping is far greater than from using sanding. Sanding will certainly not stop a spinning driving wheel dead but will gradually improve grip, so violent oscillation should not occur.

I suppose the most famous example of the risk of slipping might be when 60532 'Blue Peter' had an uncontrolled slip at Durham many years ago and suffered huge damage in a few seconds, the driving wheels having been estimated to be turning at the equivalent of 140mph. I don't know if the rods bent but I think the cylinders more or less exploded.

 

[Taunton]

It can prove difficult to shut the regulator if there is a very high flow of steam through it - of course, some regulator designs are more difficult than others. It's bad enough making a start, but the more hazardous is slipping at speed, especially where you have got the gear well down to climb a gradient. Two cylinder locomotives are the worst for this, as they will tend to "Boxing", that is the alternating thrusts on each side of the locomotive, which in extreme conditions can start lifting the driving wheels off the rails alternately in each revolution, and damage either loco or track.

Tuplin, in his books, describes a GWR Saint class two-cylinder 4-6-0 running light which got up to a claimed 120 mph when it was opened out and the regulator stuck, with all the crew, including an inspector, pulling hard at it; lever reverser would be equally hard to pull back with the steam flow. He suggested the greatest danger was from derailing due to Boxing lifting the drivers off the rails.

 

[fsmr]

Sanding also increases rolling resistance and is noticeable on smaller lighter narrow gauge and has to be carried on once started to a point where the locomotive has sufficient adhesion and momentum to overcome the original required tractive force and additional resistance of the sand once sanding stops, as the rest of the train stock and tender etc will still be on the sanded rails which doesn't benefit traction but drags the train
Rubber tyres is the way to go Vive le Metro
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Video of Blue peters massive slip and fail. at Durham
[YOUTUBE]YjsNbzg1UaI[/YOUTUBE]
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And Mayflower struggles to get any meaningful traction although the driver is doing a sterling job controlling the slip to a minimum to avoid damage to loco and track

[YOUTUBE]FWPheHChcnA[/YOUTUBE]

 

[Crossover]

Am I right in thinking that in the case of Voyagers, they don't have any normal sanders - just a "shot" sander (of which I believe there are now two bottles on each end, originally designed with one) of case of problems detected by the WSP under braking?

 

[edwin_m]

Am I right in thinking that in the case of Voyagers, they don't have any normal sanders - just a "shot" sander (of which I believe there are now two bottles on each end, originally designed with one) of case of problems detected by the WSP under braking?

The RAIB report into the Chester buffer stop collision gives details of the sanding arrangements on Voyagers, although they may have changed since then.

 

[Crossover]

The RAIB report into the Chester buffer stop collision gives details of the sanding arrangements on Voyagers, although they may have changed since then.

Yeah, I believe that is where I read about it

 

[E&W Lucas]

Goodness me, there's some total bovine above.

Steam and sand - shut off steam, allow the slipping to stop, THEN apply sand. No risk to anything. Apply sand whilst slipping, and you will bend things.

In poor conditions, a thinking driver will apply sand pre-empt the slip, applying sand before it happens.

Blue Peter's slip had nothing to with rail conditions or lack of sand, and everything to do with complete incompetence.

 

[Minilad]

Am I right in thinking that in the case of Voyagers, they don't have any normal sanders - just a "shot" sander (of which I believe there are now two bottles on each end, originally designed with one) of case of problems detected by the WSP under braking?

Correct. Built with just one. The shot will go off if A. Brake is in emergency B. travelling above 8mph C. WSP is detected. The problem with that was once the sander had been used the unit was more or less OOS which did cause problems. Now you also have a back up sander. Most drivers would prefer a conventional sander TBH as it is also useful when moving off. But apparently that is frowned upon these days.

 

[FordFocus]

If the train slips whilst taking power then the train will give the option of deploying sand for around 10 seconds. I try to avoid using sand on setting off, I'll use less power notches and then slowly notch up one by one until the train is at a reasonable speed without slipping. There are certain places where I drive where you require more power notches ( 4 or 5) because of the gradient. I'll try my best without using sand but sometimes it's unavoidable. If I'm slipping trying to get away from stations then it's likely I'll end up slipping trying to stop and I would prefer stopping so I preserve my sand where I can

The only exception I have to the above is when working on a single line I'll use sand almost immediately if WSP is detected as this can aid myself and other drivers on stopping on the single line.

Sanding is automatic whilst braking in anything other than step 1 so I have no choice over the matter.

I believe Virgin are modifying their Voyagers for automatic sanders after Chester but IIRC CrossCountry haven't committed to this upgrade from one-shot sanders but are studying it.

I'm not sure if the rules have been relaxed but in some regions, there were restrictions on informing the signaller about sander use on certain units 14x and 153 units for the risk of the track circuits not activating encase the unit wheels became beached on sand.

 

[Peter Mugridge]

beached on sand.

I see what you did there!

 

[Llama]

Yes, correct term.

Those regs still exist, they are similar to the sectional appendix instructions for one-shot sanding deployment, but for some reason the instructions disappeared out of the Northern-specific WON (despite Northern being the largest operator of 14X / 153 units) while somehow still being shown in the VT WON...

 

[E&W Lucas]

It can prove difficult to shut the regulator if there is a very high flow of steam through it - of course, some regulator designs are more difficult than others. It's bad enough making a start, but the more hazardous is slipping at speed, especially where you have got the gear well down to climb a gradient. Two cylinder locomotives are the worst for this, as they will tend to "Boxing", that is the alternating thrusts on each side of the locomotive, which in extreme conditions can start lifting the driving wheels off the rails alternately in each revolution, and damage either loco or track.

Tuplin, in his books, describes a GWR Saint class two-cylinder 4-6-0 running light which got up to a claimed 120 mph when it was opened out and the regulator stuck, with all the crew, including an inspector, pulling hard at it; lever reverser would be equally hard to pull back with the steam flow. He suggested the greatest danger was from derailing due to Boxing lifting the drivers off the rails.

Platform End Driver Alert!
You can't learn steam locos from books!!!!!!!!!!!!!!!!!
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Steam sanding seemed to die away later in the development of steam power.

You won't find too many later British steam locos that don't have steam sanders.
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There have been occasional instances with steam locomotives of sanded rails causing the buckling of coupling rods, so you can maybe understand the reluctance of private owners to use it unless essential.

Ah, the curse of the "owner's representative"!
Often with zero recognised or structured experience, and no grounding to base their opinions on.
If sand was a danger to locos, why did companies bother with the expense of fitting sanding gear, along with the cost of sand driers, labour to fill sand boxes, etc?

Complete drivel.

 

[redbutton]

On the units I drive, the sander button is only active (it illuminates) when taking power if enough wheel slip is detected. Once active, I'm free to use as much sand as I want, though sand is not to be applied over points and crossings.

However, it's rare to experience enough slip to activate the button, because the primary way to stop slipping is to just back off the power until you get above 15-20 mph. Only if you can't get there at all would the sander come into play, at which point I'd also be making a call to the signaller to report low adhesion.

Under braking, the unit will automatically apply sand when needed in step 2 or above. The WSP system is like anti-lock brakes on a car. Once you feel some slide, you leave the brake in (or increase it) until the speed comes down to whatever you deem controllable under the conditions. The unit will manage the brake pressure and apply sand to keep the wheels from locking.

 

[Crossover]

The only exception I have to the above is when working on a single line I'll use sand almost immediately if WSP is detected as this can aid myself and other drivers on stopping on the single line.

I can't remember where I heard it, but I seem to recall becoming aware from somewhere that non stoppers (TPE) Westbound through Dewsbury in the winter drop sand to aid the stopping services at the station. Not sure whether it is true or not but it amused my family thinking if a train dropped sand that anyone on the platform would get covered in it - I have since pointed out the sanding pipes that delivers the sand direct to the wheel-rail interface :P
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Once active, I'm free to use as much sand as I want, though sand is not to be applied over points and crossings.

Regarding points, is that so there is nothing that could either stop them locking in the right position or insulating the proving circuits? Why not over crossings?

 

[Taunton]

Platform End Driver Alert!
You can't learn steam locos from books!!!!!!!!!!!!!!!!!

As author Tuplin was the longstanding Professor of Mechanical Engineering at Sheffield University, Fellow of the IME, etc, I think we can pay a bit of attention to his writings, although he was a notable opponent of any need for high boiler pressure, which is where we came in ...

 

[E&W Lucas]

As author Tuplin was the longstanding Professor of Mechanical Engineering at Sheffield University, Fellow of the IME, etc, I think we can pay a bit of attention to his writings, although he was a notable opponent of any need for high boiler pressure, which is where we came in ...

None of which has anything to do with the practical skill of getting a loco up a hill in poor conditions.

 

[FordFocus]

Ah but it was in a book so it must be right.

It's quite common in low adhesion areas Crossover, a few other places on the TPE network it happens even between TOCs.

 

[redbutton]

Regarding points, is that so there is nothing that could either stop them locking in the right position or insulating the proving circuits? Why not over crossings?

The short answer is "because it's a rule".

For points, it's to keep the grit from gumming up the mechanisms.

Crossings, I'm not so sure, but usually crossings are near points, so it doesn't really matter.

 

[FordFocus]

Possibly interferes with the crossing track circuits if it hasn't got the treadles?

 

[Taunton]

Anyone have experience of Desanders at the rear of the locomotive?

 

[redbutton]

Possibly interferes with the crossing track circuits if it hasn't got the treadles?

Oh no, in this context "crossings" refers to places where one rail crosses another, like when you take a diverging route to the right at a junction, which then crosses over the adjacent line.

Or like in a diamond crossover.

I don't know of any specific reason not to use sand over a level crossing. In fact it might help since cars are always leaving oil and gunk on the rails. I almost always get a little wheelslip when trying to accelerate out of a station with a level crossing at the end of it.