Merchant Navy poor adhesion

[pH]

3 minutes ago, Gwiwer said:

(just as we all stall car engines at times - yes we do)

 

Oh no we don't!  - some of us drive automatics.

[Corbs]

Just now, pH said:

 

Oh no we don't!  - some of us drive automatics.

O/T but I have managed to stalled an automatic 

[LMS2968]

10 hours ago, Corbs said:

I guess that another factor here may be that the railhead is most likely to have moisture on it first thing in the morning?

The first train out of Bridgnorth at the start of the running week can be a challenge!

[Mallard60022]

On ‎07‎/‎04‎/‎2019 at 13:00, LMS2968 said:

Well, that was a pretty generalised put down of everyone who replied but completely failed to come up with anything of substance. Please don't generalise that no-one else knows anything about the subject: I and no doubt others on here know more than you give credit. Personally, I hold an Honours Degree in Mechanical Engineering and taught the subject for fourteen years. I have also been involved in the preservation, maintenance, repair and operation of steam locomotives since 1969. If you want to talk of coefficients of friction, factors of adhesion, power versus torque and all the rest, please do so, but don't just give us unsupported opinions like this.

 

Slipping can be caused by many factors, and while poor maintenance (incorrect spring adjustment, binding axleboxes, stiff regulator valve, etc.), indifferent track, including surface contamination, poor alignment in the vertical plane, and poor driving technique can contribute to slipping, as a general rule they are one-offs and apply to all types of loco. Pacifics are generally more prone to slipping than a 4-6-0, but I'm not sure the Bulleids are any worse than any other designers'.

Now, there's a great response to what was, I thought, going to be a decent response from another poster that turned out to be quite patronising. Thanks mate. 

Just as an aside, Nine Elms shed, especially around the coaling stage and towards the end of steam, was notoriously unkempt and the rails were knackered and covered in grot. Shed movement was also mainly carried out by the shed loco staff, many of whom just wanted to get the tings shifted.

Waterloo was also well known for being a slippery slope place on the steam side platforms as I am told that use of sanders was frowned upon (even banned?) in those areas and the loco's shed 'slippy stuff' quite liberally wherever they were standing.

Phil

[lapford34102]

Hi,

As the matters of sanders has come up an anecdote passed on by my father. Prior to '59 the Western and Southern workings out of Weymouth were pretty much separate operations in terms of footplate crew, guards etc. He said it was not uncommon that if a Western train was going up  Bincombe bank ahead of a Southern train that the Southern crew would ask the Western crew to put some sand down for them. Now whether this was specific to Bulleid's or more general I've no idea but do have a vague recollection that MN/WC/BoB sanders weren't that good.

On the matter of "slippy" locations  starting from the London end of Bournemouth Central, on a curve and an incline up under the Holdenhurst Road bridge. Starting something like the Boat train with 12 or so on in bad conditions would be a bit of a test.

 

Stu

[The Stationmaster]

2 hours ago, Mallard60022 said:

Now, there's a great response to what was, I thought, going to be a decent response from another poster that turned out to be quite patronising. Thanks mate. 

Just as an aside, Nine Elms shed, especially around the coaling stage and towards the end of steam, was notoriously unkempt and the rails were knackered and covered in grot. Shed movement was also mainly carried out by the shed loco staff, many of whom just wanted to get the tings shifted.

Waterloo was also well known for being a slippery slope place on the steam side platforms as I am told that use of sanders was frowned upon (even banned?) in those areas and the loco's shed 'slippy stuff' quite liberally wherever they were standing.

Phil

Use of sanders might well have been frowned on at Waterloo (and elsewhere) because of their possible effect on track circuits.  The GWR was very finicky at one time about sanders being used on track circuited sections of  line. 

[LMS2968]

8 minutes ago, The Stationmaster said:

Use of sanders might well have been frowned on at Waterloo (and elsewhere) because of their possible effect on track circuits.  The GWR was very finicky at one time about sanders being used on track circuited sections of  line. 

Which was why the LMS fitted hot water de-sanders for a while, to operate at the trailing end of the loco to remove sand from the railhead after the coupled wheels had passed and it had done its job.

[Mallard60022]

1 hour ago, The Stationmaster said:

Use of sanders might well have been frowned on at Waterloo (and elsewhere) because of their possible effect on track circuits.  The GWR was very finicky at one time about sanders being used on track circuited sections of  line. 

Thanks MIke, exactly so. That's what I had been told by an ex Fireman from NE, but didn't want to get told I was talking out of my sand box by some 'expert. I respect those that were there back then and those that have loads of experience of main line work now.

 

1 hour ago, LMS2968 said:

Which was why the LMS fitted hot water de-sanders for a while, to operate at the trailing end of the loco to remove sand from the railhead after the coupled wheels had passed and it had done its job.

I never knew that. Was that why the Duchesses were so sure footed?

One thing I do know is that when I 'drove' (and I say that reservedly) the big, Polish Pacific out of and back to Wolsztyn (Poznan route) some years back, it was like a thoroughbred racehorse but on a pony trekking route. Twitch the Reg and it slipped and firing it was like loading a bloody great space the size of an average bathroom! The OL49 2.6.2s on the other hand were super engines both to drive and fire; like whippets and great for start stop cross country work.

P

 

[jim.snowdon]

1 hour ago, The Stationmaster said:

Use of sanders might well have been frowned on at Waterloo (and elsewhere) because of their possible effect on track circuits.  The GWR was very finicky at one time about sanders being used on track circuited sections of  line. 

They might, and certainly the District Railway's signal engineer barred their use after an incident where a loco-hauled Southend train disappeared off the track circuits whilst tackling the climb from Ealing Broadway to Hanger Lane Junction. That prohibition carried through to London Underground and, I believe, is still in force. But, the District's reaction did not extend to the Metropolitan Railway, whose locomotives retained sanding until taken over by LU.

 

1 hour ago, LMS2968 said:

Which was why the LMS fitted hot water de-sanders for a while, to operate at the trailing end of the loco to remove sand from the railhead after the coupled wheels had passed and it had done its job.

I have a suspicion that that may have origins in the LNWR, but irrespective of that, their subsequent removal would suggest that they weren't exactly effective.

 

Jim

[Fat Controller]

2 hours ago, The Stationmaster said:

Use of sanders might well have been frowned on at Waterloo (and elsewhere) because of their possible effect on track circuits.  The GWR was very finicky at one time about sanders being used on track circuited sections of  line. 

It's still frowned upon on lines fitted with TVM-type signalling; drivers have to advise where and when they use it.

[LMS2968]

1 hour ago, Mallard60022 said:

I never knew that. Was that why the Duchesses were so sure footed?

 

Much as I admired the Stanier Pacifics, I would never have described them as 'sure footed'!

 

1 hour ago, jim.snowdon said:

I have a suspicion that that may have origins in the LNWR, but irrespective of that, their subsequent removal would suggest that they weren't exactly effective

You might be right about the LNWR, Jim, Super Ds had them. According to Ted Talbot, many men found them better than sanders at cleaning the rails and would use the de-sanders the wrong way around, as it were. They were applied only to locos with gravity sanding, and when Stanier was converted the merits of steam sanding, they rather died out. There was also a maintenance aspect. and when they didn't get this and stopped working, normal sanding returned to favour.

[The Johnster]

6 hours ago, LMS2968 said:

The first train out of Bridgnorth at the start of the running week can be a challenge!

Indeed.  As previously mentioned I've seen Gordon having trouble getting off the shed...  It worked a train of 10 mk1s on a school booking which I rode on, and had a bit of difficulty getting away from Bridgnorth, but by the time we'd got to Hampton Loade the sun had dried the dew and the loco had no further trouble, total master of it's work.  This would have been the summer of 1985.

[Mallard60022]

1 hour ago, LMS2968 said:

Much as I admired the Stanier Pacifics, I would never have described them as 'sure footed'!

 

 

Ah, so that stifles all the cooing and drooling from my LMS mates then. I only ever saw one doing a dead start on a train and that was in the Autumn of their work in August 1964 at Euston. Think they were working to Coventry on fast 'locals' or something like that at that time.

ATB

Phil

[Gibbo675]

Hi Folks,

 

In an attempt to redeem my silly self from my earlier comments which were deemed rather prickly in nature may I offer the following;

 

Valve gear:

The Bulleid valve gear is a chain derivation of Walschaerts that was designed to replicate the operation of Caprotti Gear that the locomotives were envisaged to have been fitted with but for WWII. Caprotti gear gives full port opening at any given cut off which allows for both free filling of the cylinder and a free exhaust for reduced back pressure and improved power. The Bulleid valve gear achieves this by arranging for the valve head to be accelerated from the point of cut off to the point of lead to a much greater extent than standard Walschaerts to allow fast port opening and also to allow for a period of lag at either end of the travel while the valve is open to admission.

The three troubles with this arrangement upon starting in that steam is admitted to the cylinder a lot less gradually than with standard types of valve gear as the valve opens and for want of a better description shocking the piston.  The second feature is that when the pins and bushes in the system become worn the valves will under travel at slow speeds and over travel at speed so when a slip occurs the valve will convert from a state of under travel to over travel instantly exacerbating the slip. The third feature is that in worn condition the drive r may have to apply more steam as the valves may not be opening by enough to allow for easy starting this will also affect starting.

 

Valve gear drive chains:

The type of chain used to drive the valve gear is of the Morse Hi-Vol type and was specifically chosen so that when it stretched in service it would ride out upon the teeth of the sprockets and keep the sprockets in synchronicity with each other. When a  horizontal chain is fitted up there is four inches of slack in the loose leg of the chain, should this not be the case the chain would be over stressed with the rise, fall and twist induced in to the chain. The vertical chain has a much easier life and its slack is less than an inch. This type of chain is used for cam timing in internal combustion engines for the very same reason.

There are two types of slack adjuster one is an angled bracket that is appropriately packed with shims and fixed by seven one inch fitted bolts and the other is a pivoted bracket with a screw adjuster similar to that of a brake pull rod adjuster.

The effect of a slack or worn chain upon valve events is in fact less than the difference induced by full axle box travel upon a standard type valve gear.

 

Oil Bath:

The oil bath contains forty gallons of oil and this forms a depth of only four inches when at rest, well below the axle of the driving wheel and so cannot leak out from there. The sides of the oil bath are in the main formed of the main frame plates although the undersides and ends are from 1/16” thick steel welded to light angle framings. Vibration and flex do occasionally cause small cracks to propagate, however the oil merely weeps and at a rate less than the amount of oil that may be dropped by any inside or multi cylindered locomotive. Depending upon the size and position of the cracks they may be welded without need of dropping the oil from the sump.

In my experience the greatest cause of oil leakage from the oil bath is that of hot atomised oil drifting from the vents in the top of the oil bath when the locomotives are worked hard. It is this that caused the fires in the lagging of Bullieds until belly sheets were fitted to the underside of the boilers to prevent sparks form the brake blocks from igniting the oils soaked lagging. I feel it safe to say that unless there is a newly formed crack in the oil bath or a burst pipe to the oil filters, then the amount of oil dropped from the oil bath is less than from any other inside or multi cylindered locomotive and also that any oil that does leak form the bath drops into the four foot in any case.

 

Reverser:

The type and the position of the steam reverser are both poor in view of the size and power of the engines. The type of reverser is not self trimming and will not reset itself to position should it loose its position as does the Raggonet type and should the oil seals become loose or fail then it will not hold the gear in position properly. The maintenance of the reverser is compounded by its position under the boiler just ahead of the firebox, the filling and bleeding of the oil cylinder is quite difficult due to space available to get a can into position over the filling tubes. Operation of the reversing gear is simple enough but it will only work properly when in good order which means that it needs to be checked daily.

 

Wheels:

The Bulleid derived Boxpok wheel is indeed a stiffer wheel than a comparable diameter wheel with ordinary spokes but how this actually effects slipping to any great degree I would suggest to be wishful thinking. The reason I say this is that the SNCF 141R class locomotives were delivered with both standard spoke and box spoke wheels and to my knowledge, and I stand to be corrected, no differences in adhesion or traction were ever noted.

 

Steam circuit:

Bullieds have a very large steam circuit that took on all of the ideas of Chapelon, the steam circuit is actually further increased as the engines are of outside admission type which gives a greater manifold effect for better steam distribution when working at speed. The effect of this is that should a slip start it will continue until all of the steam is used up. The regulator valves also have a large free area and as such should they be opened even a little too much then a lot of steam will be put into the steam chests with the obvious results should a slip start.

Weight Distribution:

In comparison with a Britannia a light pacific weighs eight tons less having a ton a three quarters less upon each driving axle and a comparable ratio less on both the bogie and the truck. This in itself should not be a great problem for the adhesion factors are similar to the LMS pacifics and [£] Seventy One Million which seem more than capable of starting and pulling heavy trains more than adequately.

 

My Own experience:

 

I have driven the following locomotives (BR numbers and USATC*) that are class 6 and above;

5029, 5820*, 34027, 34067, 45593, 45690, 46201, 46203, 46229, 46233, 60007, 60103, 60532, 60800, 71000 and 92203.

 

 I have to say of those listed the two most slippery locomotives of the lot were the S 160* and the 9F 92203, the worst of the passenger locomotives were the LMS Jubilees, the Duchess’ and the A4. Go figure !?!?!

 

http://1.bp.blogspot.com/-WYk8aSfb2Fw/VM4y3ptI6RI/AAAAAAAAkBI/_fwtd8VnPuU/s1600/valve_gear_dia.bmp

 

Gibbo.

[Right Away]

Regarding slipping on starting, another factor peculiar to Pacifics that has been documented elsewhere is a tendency for them to "sit back" and transfer some weight to the trailing truck; uncertain as to actually how this phenomenon was established.

 

 

[Gibbo675]

10 hours ago, Right Away said:

Regarding slipping on starting, another factor peculiar to Pacifics that has been documented elsewhere is a tendency for them to "sit back" and transfer some weight to the trailing truck; uncertain as to actually how this phenomenon was established.

 

 

Hi RA,

 

What you mention is another one of those over used "myth and legend" type topics, however should you draw a force diagram of the system that  represents a locomotive upon starting a train you will see that the reactions will indeed transfer weight onto the truck.

 

This fact is then, and without any further thought into the mathematics of the system or any other factors involved, spoken of as though pacifics with heavy trains wheelie away as would a motorcycle with its throttle pinned in first gear. I have yet to see figures to suggest the percentage change in axle loadings that would significantly cause such problems for pacific type locomotives especially the Bullieds. I'm not sure what the 0-60 mph is for the average steam locomotive but it certainly is not under four seconds as are most motorcycles.

 

I would suggest that inclined cylinders would have a much greater effect than that of weight transfer onto the trailing truck ever would even considering a minor surge in the water level toward the rear of the boiler as a result of the change from a static to a dynamic system due to the starting of a train. The centre cylinder of a Bulleid is 1:7.75 with the outer pair set at 1:40 to the horizontal. It is the centre cylinder that will have the greatest effect and the reason that the GWR under Churchward used horizontal cylinders. The locomotives are right hand lead, followed by the left and lastly centre in order of admission and the crank axle is through balanced for the originals and individually balanced for Jarvis' de-tuned ones. I am thirty years past caring to do hard sums that I didn't like doing thirty years ago, so don't ask !

 

As an aside I once worked with a chap that was involved with the initial testing of the class 91 electric locomotives, he noted that their 0-60 mph figure is twelve seconds, but only light engine. I might add that their wheels are even stiffer than Bulleid wheels by virtue of being a smaller diameter disc type wheel if only to dispel another one of those myth and legend type topics.

 

Hey-Ho, it's back to the naughty step for me !

 

Gibbo.

[Dunsignalling]

11 hours ago, Right Away said:

Regarding slipping on starting, another factor peculiar to Pacifics that has been documented elsewhere is a tendency for them to "sit back" and transfer some weight to the trailing truck; uncertain as to actually how this phenomenon was established.

 

 

Any powered vehicle will sit back to a greater or lesser extent on starting, the extent being determined by power-to-weight ratio, static weight distribution, suspension stiffness and probably a dozen other factors that I never noticed when fiddling with cars in my teens and twenties. Front wheel drive was new to most of us in those far off times but an obvious difference became clear (in those days before traction control was invented) in that it was much easier to get away quickly in a rear-wheel-drive car than a front-wheel-drive one of equal power. Weight transference in action, pure and simple but only involving two axles, so a whole lot easier to understand than the behaviour of a multi-axle steam loco.

 

Any comparison between road and rail vehicles tends to fall down for other reasons, too. The former have deformable rubber tyres and the size of the rear ones can be increased to add extra grip, e.g. for drag racing, later circuit racing and much more recently (since carrying large spare wheels around has become impractical) high performance road cars. What happens with steel wheel on steel rail is only vaguely comparable and any cause-and-effect relationship is much more complex.

 

The only difference (in both theory and practice) between the effect weight transference has on a Pacific on starting and what is does on a 4-6-0 is that, with the latter, any transference is onto a powered axle so it should (give or take) cancel out any loss of traction (whether real or assumed) elsewhere.

 

John

[Mike 84C]

During my four yrs as a steam fireman on BR I experienced  GW,LM, BR stds and a very few ER types. I can say that without doubt that the GW locos had the most sensitive regulator of all, a very positve open and closure. Why BR did'nt  adopt the type is puzzling. And I will say that in general GW locos of all types were more surefooted. Black fives, class 8's slip like goodun's, 9f's inc 92203which I have fired on real freight trains, no slipping there.

  Total loss lubrication plays a huge part in plastering an engines wheels in oil and I dare say that today's drivers  display a certain amount of bravado in their handling of the engine. The engineman in the past did not have a gallery to play to. To most it was just a job but we all know the names that were the exception.

  In my memory there was nothing better than a 9f on a fitted tomato special 45/50 vans Banbury to Bordesley in under the hour. Or belting seven bells out of an 8f from Tysley back to Banbury on a coal train, sky rockets all the way up past Fosse road box, or my driver walking all round the framing on a WR 38 at night and sticking his face around the front of the cab on the way to Reading, nearly a brown trouser moment.

 One observation on firing styles, the Eastern crews seemed to do a lot of shoveling when stood waiting for their train to arrive, drinking tea and having snap, then back on, right away, a huge slip that livens up the fire, lots of smoke and blowing off in five minutes.

  Sorry this is'nt teccy with theory and calculations, which has its place, just based on my small amount of experience. Its all a bit academic really.

    Mick

[MarkC]

5 hours ago, Mike 84C said:

During my four yrs as a steam fireman on BR I experienced  GW,LM, BR stds and a very few ER types. I can say that without doubt that the GW locos had the most sensitive regulator of all, a very positve open and closure. Why BR did'nt  adopt the type is puzzling. And I will say that in general GW locos of all types were more surefooted. Black fives, class 8's slip like goodun's, 9f's inc 92203which I have fired on real freight trains, no slipping there.

  Total loss lubrication plays a huge part in plastering an engines wheels in oil and I dare say that today's drivers  display a certain amount of bravado in their handling of the engine. The engineman in the past did not have a gallery to play to. To most it was just a job but we all know the names that were the exception.

  In my memory there was nothing better than a 9f on a fitted tomato special 45/50 vans Banbury to Bordesley in under the hour. Or belting seven bells out of an 8f from Tysley back to Banbury on a coal train, sky rockets all the way up past Fosse road box, or my driver walking all round the framing on a WR 38 at night and sticking his face around the front of the cab on the way to Reading, nearly a brown trouser moment.

 One observation on firing styles, the Eastern crews seemed to do a lot of shoveling when stood waiting for their train to arrive, drinking tea and having snap, then back on, right away, a huge slip that livens up the fire, lots of smoke and blowing off in five minutes.

  Sorry this is'nt teccy with theory and calculations, which has its place, just based on my small amount of experience. Its all a bit academic really.

    Mick

Actually, Mick, it's not 'academic' - reminiscences  like yours are real, and add to the overall story of those days of steam. Thank you for posting.

[spikey]

Gosh, this is all fascinating stuff.  Every day here is indeed a school day, but alas, the small voice from the back of the class now says "Please sir, can you just tell me how sand affects track circuiting?"

[LMS2968]

Sand is electrically an insulator, so a lot of sand insulates the train from the track circuit, which is low voltage (22V?), so the current won't pass if there is a lot on the rail head, so the train vanishes out of the signalling system. It's more a problem with gravity sanding, which delivers a lot of sand in the hope that some of it will find its way below the wheel tyre; steam sanding delivers less so isn't as much a problem.

[Fat Controller]

1 hour ago, LMS2968 said:

Sand is electrically an insulator, so a lot of sand insulates the train from the track circuit, which is low voltage (22V?), so the current won't pass if there is a lot on the rail head, so the train vanishes out of the signalling system. It's more a problem with gravity sanding, which delivers a lot of sand in the hope that some of it will find its way below the wheel tyre; steam sanding delivers less so isn't as much a problem.

The intermittent loss of detection is problematic enough when it is the detection of the train that is compromised. It becomes even more of a problem if the train relies on information passed to it via the track circuits, as in the French-designed TVM cab-signalling; intermittence here means ''three reds in cab",followed by a brake application.

[spikey]

Thank you, gentlemen

[adb968008]

I’m too young to remeber BR so I can only go off what I see...

 

focussing on the mainline, standards of driving seem today to be much better than my youth, engines are much more delicately engaged, drain cocks opened before departure and assistance from diesels behind at stations and inclines.

 

Ive never really observed 35028 slipping violently, despite it being the most common locomotive (steam or diesel) in my neighbourhood many times a year... it handles the VSOE very well, and dispels the myth of Bulleids being quiet.

 

Similar too 34046 can put on a very good show, and in recent memory Ive seen good performances from 34007/16/27/28/53/70/81/92.. i’m abit of a Bulleid fan.. however Ive oodles of video of 34067 coming to grief.. youtube has more.. Hemerdon, Filton, Martin Mill, Dover, Kingswear.. I did a trip with it to Eastbourne and every bit of footage included a slip... In its defence it was prevalent more than any other loco for a decade and a half, and it punched above its weight, but its wheels certainly span.

 

i think much of it is down to the loco, and the crew, one of my better video recordings is 34028 climbing to Cauldon Lowe, driven by a young lady and not a slip, not even on the curves or the severe incline and it sounded fantastic.

 

 

[RLBH]

42 minutes ago, Fat Controller said:

It becomes even more of a problem if the train relies on information passed to it via the track circuits, as in the French-designed TVM cab-signalling; intermittence here means ''three reds in cab",followed by a brake application.

Wildly off-topic, but this must be an advantage of the induction-based cab signalling developed in the United States and used in (amongst others) Ireland - condition of the wheel/rail interface is less critical if data isn't transmitted over it.