Prototype for everything corner.

[Wickham Green too]

2 hours ago, Michael Edge said:

... When diesels took over from steam for shunting the universal complaint was that they were too slow.

Obviously a complaint that went unheeded ....... of the pre-BR classes only the Southern trio could run above 20mph and they were followed by the class 12s and 09s* also for the Southern where a certain amount of trip work was envisaged. Why the 'standard' 08 gained the larger wheels of the 12 but was geared back down to 20mph is a mystery !

 

* to use later nomenclature

[DenysW]

On 08/02/2024 at 17:37, melmerby said:

Problem is mass doesn't scale properly in models.

 

Say you have a 7 tonne 5 planker.

A bit of fag packet maths:

Thats 7,000,000 grams. How much does the 00 wagon weigh? 30 gms? The cube root of 7 million is 191 (to three figures) so the wagon is less than 1 sixth of what it should weigh.

So a 30 wagon train should be around 570 grams, will a typical loco manage that?

 

Probably totally wrong.😀

Not wrong, at most optimistic that direct-logic is close enough.

 

So the force pushing the wagons downhill is gravity, approximated by weight divided by slope. Agreed. The force resisting this is (mostly) the frictional force from the bearings: which is non-linear with speed (especially at low speed) and there's no concensus on the actual numbers to plug into a formula.

 

Models have nothing like the frictional resistance/scale-velocity as steam-era bearings, and are also wildly different one to another.

 

Good luck.

[Michael Edge]

When I designed Cwmafon’s marshalling yard I didn’t go into any of this theory, I just set up some track on a slope and let wagons roll down it. I then had to mark all the free rolling ones with a white brake lever handle - in those days not all my stock had pin point bearings. The slope is relatively steep at first, then flattens out to level at the bottom and can work remarkably well if the shunter lets go at the right speed.

Another snag appeared at this point - since the layout has very little level track anywhere I had to give the brake vans deliberately stiff running wheels to prevent everything running away.

[KeithMacdonald]

3 hours ago, DenysW said:

The force resisting this is (mostly) the frictional force from the bearings: which is non-linear with speed (especially at low speed) and there's no concensus on the actual numbers to plug into a formula.

 

Does air resistance provide a terminal velocity?

[Compound2632]

38 minutes ago, KeithMacdonald said:

Does air resistance provide a terminal velocity?

 

The rolling resistance does.

[Jeremy Cumberland]

8 hours ago, KeithMacdonald said:

 

Does air resistance provide a terminal velocity?

If you dropped your rolling stock out of an aircraft it would, I'm sure.

[billbedford]

Of course, the trick to getting shunting to work well is to make your wagons in a way that they can be used as a substitute for a spirit level when making shelves. 

[Compound2632]

4 hours ago, billbedford said:

Of course, the trick to getting shunting to work well is to make your wagons in a way that they can be used as a substitute for a spirit level when making shelves. 

 

That then puts one under the obligation of building a perfectly flat and level layout...

 

I've found that my EFE LSWR covered goods wagon rolls away in the direction of one end whichever orientation I put it down in*, which has me worried!

 

*on its wheels, not on its sides or roof, obviously, but I know what nit-pickers you are.

Edited February 10 by Compound2632

[Jeremy Cumberland]

2 hours ago, Compound2632 said:

I've found that my EFE LSWR covered goods wagon rolls away in the direction of one end whichever orientation I put it down in*, which has me worried!

 

*on its wheels, not on its sides or roof, obviously, but I know what nit-pickers you are.

Rolling away in the direction of one end is quite normal. When I start to worry is when they roll away to one end when I put them down one way round and roll away to the other end when I put them down the other way round.

[Wickham Green too]

1 hour ago, Jeremy Cumberland said:

... When I start to worry is when they roll away to one end when I put them down one way round and roll away to the other end when I put them down the other way round.

You've obviously confused their homing instincts !

[Mol_PMB]

Just now, Wickham Green too said:

You've obviously confused their homing instincts !

Or the layout's on a seesaw and the weight of the wagon is enough to tip it one way or the other?

Either that or someone needs to have a stern word with Isaac Newton.

[Wickham Green too]

13 minutes ago, Mol_PMB said:

Or the layout's on a seesaw and the weight of the wagon is enough to tip it one way or the other? ...

As far as we know, of course, Jeremy might live on houseboat !

[melmerby]

7 hours ago, Compound2632 said:

I've found that my EFE LSWR covered goods wagon rolls away in the direction of one end whichever orientation I put it down in*, which has me worried!

That happens when the wheels one end are bigger than the other.........😄

[The Johnster]

On 08/02/2024 at 12:57, Michael Edge said:

Interesting bit of loose shunting, just demonstrates what I always say about slow shunting on layouts - it was actually always done as fast as possible and that 350 was being flogged along flat out there.

 

Well, there's shunting and then there's shunting.  On the real railway the basic principle was that everybody wanted to go home early, but they wanted to go home just the same and not be killed on the job*, so it was best to keep things safe.  I, too, get irritated by snail-racing shunting on layouts, but it wasn't 'always done as fast as possible' either.  Depends on the situation; taking as the first example, shunting with a pickup goods in a small goods yard on a branch of at a small main-line station, the most common situation on model railway layouts.  You will usually have only one man on the ground, the guard, and a shunter if you are lucky, which means that there is no point at all in rushing about the place because, after the guard has uncoupled the first cut, he will send you back out over the points he has to change to accept the next cut, and this reduces you effectively to a brisk walking pace, which is still a lot faster than some people shunt on exhibition layouts...

 

Second example, propelling wagons into goods sheds (even big ones where capstan/rope haulage was not being used), cattle docks, or end-loading docks; this is where snail-racing is justified.  Clearances are tight and there may be people working on stock already in the siding, so it is very much a case of softly softly catchee monkee.  Extreme caution is the order of the day; I remember propelling NPCCS into the old Brunel Goods Shed at Pontypridd, where the clearance between the side of the loco and and the doorframe was measured with feeler gauges.  We were called forward by a man we could not see inside the shed relaying hand signals via two banksmen.

 

Third example is more the sort of thing we are discussing here; marshalling yards, and reception sidings.  Here loose shunting is normal, especially but not exclusively in the case of hump yards controlled by retarders, and wagons are banged about with cheerful abandon.  Several times during a working day there will be the sort of bang that will cause everybody to look up, followed by a cloud of brown brake-block dust shaken off the wagons.  Derailments are not uncommon.  This is what shocvans were designed to cope with.  Challenging to recreate convincingly on a model; loose shunting at scale speeds with free-running stock is possible, but a good bit of practice is needed before a decent standard of performance will be achieved, and wagons shunted this way are often controlled manually by shunters on the ground with brake sticks.  It can probably be done, but the real-life skills are dying out, nobody's done anything like this for the last five decades on the real railway; the question becomes, can it be done realistically?

 

Speed in yards, loco or goods, is limited to 15mph by the General Appendix; no speed restriction signs are necessary.  in goods yards the loco is controlled by handsignals from the ground staff, under the authority of the yard foreman, and in loco yards movements take place under the authority of the loco yard foreman but drivers will move locos about on their own accord.  Whistle/horn sounded before moving off and a sharp lookout kept.  This is why most larger sheds had an accepted one-way system in operation.  The 15mph is why 350hp shunting engines, originally concieved as 24/7 engines for work in marshalling yards, each releasing three steam engines for other work, were built to run at that speed; it was one of the failings of the 1955 Modernisation Scheme's locomotive policy that a successful diesel replacement for the many six-coupled steam tank engines which were used for yard shunting but which very often were also utilised on local passenger, trip, and transfer freight jobs was neither foreseen nor, except perhaps in the case of the 40mph Class 14, built. 

 

This is why drivers, and to a greater extent signalmen, complained that the 08s were too slow; they could not keep out of the way of faster traffic on running lines, and with long trains took far too long to clear blocks and junctions.  As pure 'yard switcher' shunting engines they were probably the best that has ever been seen in the UK, but when they were required to the running-line duties of the Jinties, J50s, Panniers, &c that had previously done the work as well as local passenger, trip, & transfer jobs, they were hopelessly inadequate; to be fair that's not what they were originally designed for!  They had to take on even more transfer and trip work after the failure of some of the Modernisation Plan Type 1s, notably Classes 15 and 16, and the diversion of the successful Class 20s to double-headed MGR work.

 

Summing up, for the purposes of shunting on layouts, reasonable speed for yard work, snail-racing if you're propelling into a shed or a dock, or anywhere men may be working on the wagons (don't forget, pre-1963 there were mileage sidings where wagons were unloaded by men not employed by or necessarily familiar with the safety issues of the railway), fairly slow for carriage shed work, and bang 'em around loose to your heart's content in marshalling yards.  Your engine shouldn't go faster than scale 15mph but the wagons could, and did, exceed that in hump yard work.  For hump yards, the propelling movement over the hump is dead slow because the wagons have to clear the hump at a set rate, but once the wagons are gravitating it's a free-for-all...

 

 

*Marshalling yard shunting was a young man's game, for the quick and (all too often) the dead, as was carriage shed shunting where getting caught between vehicles was lethal.  In goods yards the big danger was tripping or stumbling and being caught under wagons.  Another one, discouraged officially, was riding a loose-shunted wagon on the shunting pole you were using to brake it; shunting poles were not designed for this and if it broke, it would do so without warning and would tip you under the wagon...  You had to keep your wits about you, at all and any time!

[Artless Bodger]

A member of the old Reed's club showed us some film he'd taken in Germany (early 1980s) in a marshalling yard where loose shunting was taking place, men were employed (he said Gastarbeiter) to drop metal sledges onto the railhead just before a wagon passed, to slow and stop them. He said life expectancy was short.

[LMS2968]

Hence Gastarbeiter - foreign workers.

[65179]

21 hours ago, The Johnster said:

 

Well, there's shunting and then there's shunting.  On the real railway the basic principle was that everybody wanted to go home early, but they wanted to go home just the same and not be killed on the job*, so it was best to keep things safe.  I, too, get irritated by snail-racing shunting on layouts, but it wasn't 'always done as fast as possible' either.  Depends on the situation; taking as the first example, shunting with a pickup goods in a small goods yard on a branch of at a small main-line station, the most common situation on model railway layouts.  You will usually have only one man on the ground, the guard, and a shunter if you are lucky, which means that there is no point at all in rushing about the place because, after the guard has uncoupled the first cut, he will send you back out over the points he has to change to accept the next cut, and this reduces you effectively to a brisk walking pace, which is still a lot faster than some people shunt on exhibition layouts...

 

Second example, propelling wagons into goods sheds (even big ones where capstan/rope haulage was not being used), cattle docks, or end-loading docks; this is where snail-racing is justified.  Clearances are tight and there may be people working on stock already in the siding, so it is very much a case of softly softly catchee monkee.  Extreme caution is the order of the day; I remember propelling NPCCS into the old Brunel Goods Shed at Pontypridd, where the clearance between the side of the loco and and the doorframe was measured with feeler gauges.  We were called forward by a man we could not see inside the shed relaying hand signals via two banksmen.

 

Third example is more the sort of thing we are discussing here; marshalling yards, and reception sidings.  Here loose shunting is normal, especially but not exclusively in the case of hump yards controlled by retarders, and wagons are banged about with cheerful abandon.  Several times during a working day there will be the sort of bang that will cause everybody to look up, followed by a cloud of brown brake-block dust shaken off the wagons.  Derailments are not uncommon.  This is what shocvans were designed to cope with.  Challenging to recreate convincingly on a model; loose shunting at scale speeds with free-running stock is possible, but a good bit of practice is needed before a decent standard of performance will be achieved, and wagons shunted this way are often controlled manually by shunters on the ground with brake sticks.  It can probably be done, but the real-life skills are dying out, nobody's done anything like this for the last five decades on the real railway; the question becomes, can it be done realistically?

 

Speed in yards, loco or goods, is limited to 15mph by the General Appendix; no speed restriction signs are necessary.  in goods yards the loco is controlled by handsignals from the ground staff, under the authority of the yard foreman, and in loco yards movements take place under the authority of the loco yard foreman but drivers will move locos about on their own accord.  Whistle/horn sounded before moving off and a sharp lookout kept.  This is why most larger sheds had an accepted one-way system in operation.  The 15mph is why 350hp shunting engines, originally concieved as 24/7 engines for work in marshalling yards, each releasing three steam engines for other work, were built to run at that speed; it was one of the failings of the 1955 Modernisation Scheme's locomotive policy that a successful diesel replacement for the many six-coupled steam tank engines which were used for yard shunting but which very often were also utilised on local passenger, trip, and transfer freight jobs was neither foreseen nor, except perhaps in the case of the 40mph Class 14, built. 

 

This is why drivers, and to a greater extent signalmen, complained that the 08s were too slow; they could not keep out of the way of faster traffic on running lines, and with long trains took far too long to clear blocks and junctions.  As pure 'yard switcher' shunting engines they were probably the best that has ever been seen in the UK, but when they were required to the running-line duties of the Jinties, J50s, Panniers, &c that had previously done the work as well as local passenger, trip, & transfer jobs, they were hopelessly inadequate; to be fair that's not what they were originally designed for!  They had to take on even more transfer and trip work after the failure of some of the Modernisation Plan Type 1s, notably Classes 15 and 16, and the diversion of the successful Class 20s to double-headed MGR work.

 

Summing up, for the purposes of shunting on layouts, reasonable speed for yard work, snail-racing if you're propelling into a shed or a dock, or anywhere men may be working on the wagons (don't forget, pre-1963 there were mileage sidings where wagons were unloaded by men not employed by or necessarily familiar with the safety issues of the railway), fairly slow for carriage shed work, and bang 'em around loose to your heart's content in marshalling yards.  Your engine shouldn't go faster than scale 15mph but the wagons could, and did, exceed that in hump yard work.  For hump yards, the propelling movement over the hump is dead slow because the wagons have to clear the hump at a set rate, but once the wagons are gravitating it's a free-for-all...

 

 

*Marshalling yard shunting was a young man's game, for the quick and (all too often) the dead, as was carriage shed shunting where getting caught between vehicles was lethal.  In goods yards the big danger was tripping or stumbling and being caught under wagons.  Another one, discouraged officially, was riding a loose-shunted wagon on the shunting pole you were using to brake it; shunting poles were not designed for this and if it broke, it would do so without warning and would tip you under the wagon...  You had to keep your wits about you, at all and any time!

 

We've had it on here before, but here's a lovely bit of film (without sound sadly) of Mottram Yard on the Woodhead route neatly illustrating the speed of hump yard shunting and some of the dangers @The Johnster discusses including riding on the shunter's pole right at the end of the film:

 

 

Simon

[Budgie]

22 hours ago, The Johnster said:

and bang 'em around loose to your heart's content in marshalling yards. 

 

But don't damage the customer's goods as a result, because your employer will have to pay them compensation.

Edited February 11 by Budgie

[The Johnster]

Which is, as I said, what shocvans were for...

[DenysW]

On 09/02/2024 at 23:55, KeithMacdonald said:

Does air resistance provide a terminal velocity?

I can only answer for the 1930s real thing, not models. Air resistance only seems to become significant over (roughly) 90 mph, so most of the LNER and LMS streamlining was actually not serving a technical purpose most of the time. It was also apparent that it's not the head-on air resistance that matters, it's the partially-sideways-on wind that messes around with the trains.

 

If the rolling resistance at that time had been addressed by 100% roller bearings on locomotives and carriages then possibly air-resistance would have been more important down to lower speeds.

 

The terminal velocity is where the resistance to movement is equal to the force applied by a combination of the locomotive and gravity (blinding glimpse of the obvious). As the force applied by reciprocating steam engines drops off with velocity due to pressure loss through the valves, it's most likely that this sets the terminal velocity on the flat, and the slope (up or down) sets it otherwise. Better/bigger valves give less pressure drop but don't completely eliminate the effect.

[Colin_McLeod]

On 08/02/2024 at 15:51, KingEdwardII said:

until I worked out that the floor of the railway room had a slope of almost an inch from one side to the other, which I'd faithfully reproduced on the layout by building all the baseboard supports the same height. Cue some extra woodwork...

 

I suspect many others have made the same mistake.  I know I did once (but I think I got away with it 😉)

[DenysW]

8 hours ago, DenysW said:

As the force applied by reciprocating steam engines drops off with velocity due to pressure loss through the valves

As a bit of an afterthought ...

 

If you really wanted to design a 150 mph steam engine, then the least-wrong answer is probably a big-boiler 4-2-2 "single" with a turbine to eliminate the problems with reciprocating engines, and prepare to tolerate the fact that the biggest boiler that won't destroy the track probably limits you to three or four 40-ton carriages. The "single" eliminates the remaining hammer from connecting rods. I make no claims for efficiency, just speed - a turbine optimised for, say, 125 mph is not going to be  thing of beauty on sections of track requiring 50 mph max.

[john new]

A Single's unencumbered ability for speed was IIRC why Stirling built No 1 etc. Was he the CME with the (alleged/true?) quote about locomotives with coupled wheels being like a man running with his breeks (trousers) down?

 

For the theoreticians amongst us I wonder what the theoretical maximum speed for say a replica GNR No 1 or the Caley 123 would be with modern laser aligned erection, roller bearings, fully honed steam passages and some form of mechanically aided firing or oil? I guess for stopping power though it would need something like a brake-tender behind it. 

 

Perhaps one for the Imaginary Loco's thread though not this one.

 

Edited February 15 by john new
Extra note added.

[62613]

15 hours ago, john new said:

A Single's unencumbered ability for speed was IIRC why Stirling built No 1 etc. Was he the CME with the (alleged/true?) quote about locomotives with coupled wheels being like a man running with his breeks (trousers) down?

 

For the theoreticians amongst us I wonder what the theoretical maximum speed for say a replica GNR No 1 or the Caley 123 would be with modern laser aligned erection, roller bearings, fully honed steam passages and some form of mechanically aided firing or oil? I guess for stopping power though it would need something like a brake-tender behind it. 

 

Perhaps one for the Imaginary Loco's thread though not this one.

 

Dugald Drummond, no?

[Wickham Green too]

2 hours ago, 62613 said:

Dugald Drummond, no?

The gentleman whose double singles were - er - rather less successful than his 4-4-0s .... notably his 'Greyhound' T9s.