jim.snowdon
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Posts posted by jim.snowdon
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1 hour ago, Jeremy Cumberland said:
I can't say that I have watched the St Bees signaller particularly closely, but surely they have to put each token through the instrument, which would change the sequence of operations (notably the signaller not taking the token from the driver of the Barrow train and giving it directly to the driver of the Carlisle train).
What the St Bees signaller is alleged to be doing is only possible if the section signals are not interlocked with getting a line clear for the section, and since that principle has been progressively built into signalling for many decades I am surprised that it hasn't spread to St Bees. Either way, what the signaller is doing is in conflict with the rules, even if it is a fudged form of one engine in steam working.
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3 hours ago, PerthBox said:
RETB uses hydro-pneumatic self-restoring points. These use a gas filled accumulator which operates a hydraulic actuator; there are no springs involved. As noted above certain locations on the West Highland line (Garelochhead, Ardlui, Taynuilt, Bridge of Orchy, Rannoch, Spean Bridge) are set up for right hand running to make it simpler to shunt sidings.
That's just a hydraulic spring. The important feature of that arrangement is that the return stroke of the actuator can be damped so that the switches return to the normal position quite slowly. It saves wear and wear on the mechanism as otherwise it would return to normal between the bogies on each carriage.
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On 21/06/2021 at 12:28, The Stationmaster said:
You are correct Chris - the fuel trains effectively only supplement the pipeline/act as a replacement for it when it is undergoing maintenance or run in order to make sure the unloading system is in good working order.
Alas the ravages of building on former railway land are all too frequent nowadays.
The fuel train is a regular working originating from the Isle of Grain and is a completely different flow to the pipelines which, from memory, originate from the Fawley refinery.
It's a flow that has been going, possibly on and off, for some time. I was involved in a project to procure a fleet of tank cars for Q8 Petroleum around 1990 that was scuppered by the actions of one S Hussein.
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There is no hard and fast answer to this one, although left hand running in loops is a general convention. It all depends on how the layout is signalled, and any layout can be signalled in accordance with what the customer, ie the Operator, wants (and is prepared to fund). I don't recall the Board of Trade having any 'rules' on the subject either, although there was the common sense design principle that trains running in to a loop should have the straighter route, the presumption being that trains running out of the loop would normally be starting from rest or at a low speed and would not be inconvenienced by any speed restrictions through the reverse curves at the end of the loop.
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1 hour ago, keefer said:
Going OT, I think there were some lines like this in NW London - former Underground tracks also used by BR 3rd-rail units, had the 4th rail retained but lowered when the Underground services stopped running.
Incidentally, the cl.501 EMUs were originally 4th-rail but were changed to 3rd-rail in the '60s.
The lines between Euston and Watford were built as a joint exercise with Underground Electric Railways of London (UERL), the owners of the Bakerloo Line. That determined the use of 4-rail electrification from the beginning, and in technical terms, 4-rail avoided any arguments over stray current and interface arrangements with the Signal Engineers. At the time, c.1915, 4-rail electrification was effectively the London area at the time, with only the Central London and City & South London Railways being 3-rail (and the latter was actually a 3-wire DC system with +550V on one line and -550V on the other). The LSWR's 3-rail electrification was only just about to come on line at the time.
With the Watford DC Lines committed to being 4-rail, it was an inevitability that the whole of the North London system would also be 4-rail, and there it stayed until BR decided to convert what was left of it to 3-rail in 1970 for reasons that I have never discovered.
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On 05/04/2024 at 14:26, Dunalastair said:
Thankyou. That pins it down nicely. Three-rail electrification has been and is familiar, but I cannot think of many other examples in the UK outside London of four-rail.
I might try to represent that if the model ideas come to fruition, but at 1:148 it might not be very visible!
Apparently the LYR electric units were originally four-rail
https://en.wikipedia.org/wiki/LYR_electric_units and https://lyrs.org.uk/electrification/
Photographs of four rail LOR trains still seem elusive, but four rails on the L&YR seems easier to find
also at
The history of electric traction in Liverpool seems less than straightforward, with the Mersey Railway also being four rail to an American design.
https://en.wikipedia.org/wiki/Mersey_Railway
I must read more!
The L&YR's Southport Line may look like a four rail system at first sight, but the centre rail was only a reinforcement rail for the return circuit, bonded to both running rails and not in contact with anything on the train.
In contrast, the Mersey Railway was electrified using positive and negative conductor rails, ie 4-rail, but the Wirral Railway, which connected with it, was electrified using the standard 3rd rail arrangement. Wirral Railway trains were equipped with centre negative shoegear and automatic contactors that changed the negative connection from running rail to the 4th rail at the changeover point at Birkenhead Park.
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1 hour ago, Cwmtwrch said:
I agree there is some welded replating in the visible side, but the doors appear to have a vertical division in them, suggesting to me that they may be 'cupboard' doors rather than the standard type, possibly welded replacements for pressed originals.
The rivet pattern would also suggest side hinged 'cupboard' doors, as would the presence of a door hinge visible on the right hand side (as posted) at the top of the second stanchion. That, plus the generally welded construction, would indicate it as an ex-LNER loco coal wagon.
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Falcon in Swindon Works, 1970
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On 10/03/2024 at 10:09, Artless Bodger said:
Did the higher speed of the engines enable a direct coupling to the generator? I think the Sulzer and EE engines had step up gears between crankshaft and generator.
I'm not aware of any British diesel electrics having anything but a direct connection between the engine and generator shafts. The common approach was for the generator to have only an outer end bearing, the inner end of its shaft being supported by the engine crankshaft.
US practice, from what I have seen, tends towards making the generator mechanically independent of the engine, but still coupled directly.
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3 hours ago, Wickham Green too said:
I'd say that first wagon is a near clone of the second ...... the same shape door bumpers so probably GWR too - but it's got wider corner plates.
Narrower (9"?) corner plates were a feature of wartime built wagons, introduced as an economy measure compared to the traditional 12" plates.
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2 hours ago, ikcdab said:
no because the running line goes behind the camping coaches
From a check on the OS 25" map for c.1928*, the only siding, and therefore lodging for any camping coaches, is on the landward side of the running line. Thus, they would, in this picture, be hiding behind the train.
The absence of the pillbox that was built around the outcrop seen in the picture would also date the photograph to pre-1939.
The same map also shows nothing in regard to the tea rooms that are in the background, so all that can be said, in my view, is that the picture was taken some time between 1928 and 1939.
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6 hours ago, slilley said:
There was never a Class 41 Warship. It is a myth. The two digit class nos were prepared by the CR (T&RS) AE Robson in March 1968 after the D600 Warships had been withdrawn. I have a copy of the list and can assure everyone that those locos do not appear.
Simon
Which will always prompt the question as to why 41 was unused, or what it was intended for.
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2 hours ago, Wickham Green too said:
Pretty much - but then you have the oddballs with two engines, radiators etc. thrown into the mix to confuse everybody !
The only certainty will be that the No.1/A end will be the end where Forward on the controller sets up the Forward train line. But then, with two engines and, therefore two traction equipments, one will be in Forward, the other in Reverse.
None of this will be obvious to the bystander however.....
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The insides of PO coal wagons (and railway owned examples, including the BR steel ones) were unpainted save for any metalwork on wood bodied wagons, which was generally given a 'black japanned' finish at construction. Open merchandise wagons were similarly unpainted when wooden bodied.
The unknown is the pre-BR steel bodied coal wagons - BR adopted a policy of using a self-weathering grade of steel (Corten) but how widespread that practice was for pre-BR wagons is unknown to me.
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There is a view in circulation amongst railway modellers that it was a requirement, if not a BoT requirement, that vehicles carrying livestock, especially in freight trains, should be coupled immediately behind the locomotive so as to reduce shocks to the occupants. It certainly seems plausible, and would be consistent with many livestock wagons being equipped with screw couplings and vacuum brakes/through pipes.
The question is was this ever set out in the railways rules or general appendices?
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29 minutes ago, Stoke West said:
Chippenham had two bays , up to calne , down to Bath and Trowbridge both either end on the down face of the now island platform , the cut back canopy for the Calne bay is still there . The not in use platform face was the down main
Intriguing. My knowledge of Chippenham station dates from long after the branches had gone and the Calne branch bay is much the more obvious feature.
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3 hours ago, Harlequin said:
Off the top of my head, mainline junction stations with branch bays:
- Didcot
- Newbury
- Exeter St. David's
- Whitland
- Tiverton
- Newton Abbot
- Bourne End
- Kemble
There are a lot more, I'm sure. It seems to be a common pattern and you can understand why - it avoids all the difficulties that you described above and allows branch trains to connect to main line trains without holding up operations.
And then there's Chippenham, which I recall as having the bay between the up and down lines, and not directly accessible from the latter.
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12 hours ago, DCB said:
The problem with signalling un prototypical layouts is you can't signal them prototypically!
Yes you can - you follow the prototype signalling principles, just as the signal engineers had to when faced with a new track layout.
12 hours ago, DCB said:The branch bay is very much a Model railway ploy rather than a prototype feature.
Probably because it added operating interest, which is generally what model railway operation is all about. The bog-standard railway station with two platforms and a goods yard is pretty boring to operate.
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16 hours ago, Compound2632 said:
both of which conform to the Board of Trade rules, of course.
They were more 'strong recommendations' than actual Rules with legal force. They were essentially what the Railway Inspectorate expected to see and considered to be good practice. If you complied, then approval would normally be forthcoming. You could deviate from them, but you had to have convincing reasons why (a) compliance was not reasonably practicable and (b) that what you proposed was no less safe than a compliant arrangement.
The only legal rules were those set out in the various Regulation of Railways Acts, which marked those relatively rare occasions when the Inspectorate's powers of persuasion had to be backed with force to deal with recalcitrant railway companies.
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On 03/12/2022 at 13:41, 37114 said:
I guess so, Heljan seem to be pricier than Dapol but I took the view I wanted one and don't buy lots of new stock now. I also thought in terms of siding length, £ for £ they are not too much more expensive than a couple of kit built vans by the time you have put paint and transfers etc
I'm sure Heljan's pricing policy is the classic one of 'screw the customer for as much as they will pay', otherwise known as setting the highest price that the market will bear. The unfortunate part is that people make the comparison against what it would cost them to build one, or more likely, what it would cost to get one built, ignoring the fact that these RTR models are mass produced, with all the economies of scale that that brings.
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It is an ISO container, or more specifically an integral bodied tank with ISO length and width dimensions and twistlocks on the corners. Not that common, relative to the number of ISO tank containers that had the tank contained within a complete frame, as at the head end of that train.
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3 hours ago, Cwmtwrch said:
Interested to see that some are marked with the bearing size - one 9 x 4 and two 9 x 4¼.
Marking the axlebox with the journal size is a normal, and necessary, practice. Bearing brasses come in a range of different sizes. If it's not on the cover, it will be somewhere else on the casting.
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1 hour ago, Gordon A said:
If axle boxes are built to standard RCH dimensions then they become interchangeable, apart from the roller bearings which I believe are designed for faster train speeds.
But still fit in the RCH axleguard. That's governed by the adaptor housing in which the roller bearing fits.
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From my understanding of current signalling design, signal spacing is determined on the basis that the braking is initiated at the point of passing the signal, not the point at which it was sighted. That is a necessary worst case condition as the visibility of the signal in different weather conditions cannot be presumed. Early sighting is therefore a bonus.
Sighting, in the context of being able to identify the signal aspect against the background, is an important consideration, particularly when it is a stop aspect. There is also the issue of being able to see the signal at all when the train is stopped at the expected stopping point. This has become more of an issue with the way modern stock no longer has side windows convenient to the driver. Gone are the days when the driver could poke his or her head out of the cab side window and look at the miniature aspects (the 'pig's ears') on the side of the signal head.
The worst case elements are taken into account in the standards applicable to both signalling and rolling stock.
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Were there ever any 5-way points?
in UK Prototype Questions
Posted
Stub switches go back to the early days of railways, when the specialised machine tools required for making tapered switch rails were often not available. By comparison, the machining involved in making a crossing is much simpler. Only the crossing nose requires any machining, the rest being a matter of rail bending.