mainline running max speed on Steam Engines

hi i have been thinking locos on the mainline (steam engines), have a max speed so if two are double headed like say Kinlet Hall and Tangmere, kinlet hall has a max mainline speed of 60MPh and Tangmere 75MPh.

Would the max speed of the two double headed locos be the 60MPh of Kinlet hall or 75MPh of Tangmere on a mainline railtour.

Josh

 

60MPH , the lowest max speed of ether engine is what is used as the max speed .

 

Standard railway rule that any train consist will have the maximum speed of the slowest vehicle in the consist - therefore train speed limited to 60 mph of Kinlet Hall all other factors permitting.

 

thanks for the answers.

josh

 

Just to throw a spanner into the works, as I would like to know the answer to this quiestion

What would the top speed be for 2 tender locomotives in top and tail formation on a line where the permanant speed restiction is greater than 60MPH? would they be running at 45mph (AFAIK is the max speed running tender first) or would it be the leading locomotive's authorised maximum speed?

Thanks in advance

Jamie

 

From memory the 45mph for tender first steam locos is due to propelling the fixed wheelbase tender. Steam locos quite often get dragged around on the rear of trains for operational purposes (Folkestone East to Ashford or into terminal stations) and I don't think the restriction applies as the tender isn't the leading vehicle. I'll have a poke aroud Rules of the Plan to see if there is anything in print..


EDIT. It's shown in the Sectional Appendix, which isn't accessible via the NR web site. if I remeber I'll look on Monday.
Cheers, Neil

 

Taking this a stage further, if an engine is being towed, as opposed to under it's own power (e.g. an A4 being towed in light steam by a class 67), does that still have to stick to the speed limit for the locomotive, even though it isn't actually doing any of the work?

 

It depends on why the loco is being towed; if the loco has a mechanical fault then - depending on the fault - a specific speed limit directly related to the fault may be imposed and this will be the maximum speed for the convoy.

If the tow is being done in order for one or more locomotives to use a single path for a particular move then the rule noted above re slowest vehicle in convoy will apply for that move.

 

I think the loco's maximum forward speed can be used in top and tail formation providing it's the loco at the rear rather than the tender, think it's basically as long as the tender is not the lead vehicle in the formation.

Few years ago Vintage Trains ran a tour with 5690 & 45305 in top and tail (LMS HST \/ ) though i never saw it go quicker than about 40MPH, given the route it took it must of gone faster for pathings sake.

Is the tender first restriction just down to stability ?, i thought sighting came into it too ?.

 

Think you'll find its down to stability factor due to sloshing water in the tender. If the tender leads then the water movement will increase the normal instability which arises from the rigidity of the tender frame - especially on curves. In normal service this obviously doesn't arise because the tender is drawn along by tye locomotive which is inherently more stable and can absorb the oscillations from the tender, whereas in backwards running there is no restraint.

I believe there is also a Law of Physics which note that at certain frequencies an oscillation can generate its own momentum which increases to the point of destruction - as shown by the classic film clip of the Brooklyn Bridge ( IIRC ) actually oscillating in the wind and then generating its own momentum to the point of literally tearing itself apart !

Although sighting is a factor - hence the tender designs on the BR Standards - the risk of derailment arises from instability rather than simple excess speed.

 

I think the phrase you are looking for is 'harmonic resonance' :smt002

Regards,

Dan

 

I don't think that it is down to the sloshing of the water in the tender, more down to the various forces on the tender mainly through the drawbar and the leading wheelset, which cancreate a rotational couple. (That's a rotating force.) It applies to any 4, 6 or 8 wheel rigid vehicle. It's hard to explain in words but if you have a model railway, try pushing such vehicles around a curve and put some resistance on the leading vehicle. The chances are the whole lot will concertina and derail. If the vehicle is being hauled the forces are totally different and tend to make it more stable. A bogie has its foces transmitted through the centre pivot and its a fundamental fact that such a bogie does not know whether it is being pulled or pushed, the forces are essentially the same. That is why you are able to propel bogie vehicles at high speed.
Before anyone jumps in, the above is a simplistic analysis. Vehicle stability and suspension is a much more complex science.

 

It still has to do more work than you think.... Trust me! You can can get caught out going up an incline..

 

Returning to speeds, you also have to consider the rules pertaining to loco hauled trains, found here:

http://www.rgsonline.co.uk/Rule_Book/Fo ... A434F46%7d

Essentially, you often can't do the line speed with a conventional loco hauled train.

 

Can I throw another spanner in to said works.

What happens if you have two locomotives coupled tender to tender, with the lead loco boiler first?

Is it 75 or 45 MPH ?

 

uh.....

Dont quite follow that, So if you had to Black 5's coupled tender to tender hauling a train wat is there limit is it the Boiler first limit or is it the limit of the one running tender first ?

 

I couldnt tell you that one! One would surely have to keep up with the other and what they are set at (Limited) in reverse gear, I suppose?

 

Depends on the train weight, you could always have the engine facing the right way doing the lions share of the work.

Say for example it's two black 5's tender to tender, given there's no tender leading the formation, combined with the "pull" from the lead engine aiding the train engines tenders stability i'd imagine the top speed would be the maximum forward limit for the class (60), not sure if thats what the rule book says but taking all the theories mentioned into account it seems the logical answer.