Point machines on an SR branch line

[Dunsignalling]

You might think that, but....

 

If the train is shunted back to the stop-blocks after the run-round, then at least one if not two (or more) coach bogies will run over the trailing point in a facing direction when the train departs again. Certainly there were instances where a FPL was provided, but without knowing the arrangements everywhere I can't comment further than to say that my impression is that those were in a minority.

The only place that I was familiar with that had such an FPL was Seaton, where pushing back was certainly necessary on summer Saturdays to accommodate the Waterloo working that serviced the holiday camp. Otherwise, the service was generally operated by a p-p set so the point presumably stayed bolted for most of the time. 

 

Would I be right in guessing that, where FPLs were so provided, they may only have locked normal to ease maintenance?

 

John

Edited January 26, 2018 by Dunsignalling

[TheSignalEngineer]

The only place that I was familiar with that had such an FPL was Seaton, where pushing back was certainly necessary on summer Saturdays to accommodate the Waterloo working that serviced the holiday camp. Otherwise, the service was generally operated by a p-p set so the point presumably stayed bolted for most of the time. 

 

Would I be right in guessing that, where FPLs were so provided, they may only have locked normal to ease maintenance?

 

John

On the LMR where an FPL was provided it would stand in with the lever normal. The operation was pull 1 to release the frame, pull 2 to unbolt the points, pull 3 to reverse the points. This way the frame release could not be given back to the controlling box without the points being bolted.

[bécasse]

The only place that I was familiar with that had such an FPL was Seaton, where pushing back was certainly necessary on summer Saturdays to accommodate the Waterloo working that serviced the holiday camp. Otherwise, the service was generally operated by a p-p set so the point presumably stayed bolted for most of the time. 

 

Would I be right in guessing that, where FPLs were so provided, they may only have locked normal to ease maintenance?

 

 

 

The point would have been worked for the goods as well - and the p&p carriages certainly sat over the point in normal working.

 

It was usual practice on the Southern (and presumably elsewhere as well) for points to only be boltable when set for a direction which could be used for (facing) passenger traffic - so here boltable only when set normal for the platform road but at a junction boltable for either route.

[RailWest]

The point would have been worked for the goods as well - and the p&p carriages certainly sat over the point in normal working.

 

It was usual practice on the Southern (and presumably elsewhere as well) for points to only be boltable when set for a direction which could be used for (facing) passenger traffic - so here boltable only when set normal for the platform road but at a junction boltable for either route.

Sadly for your argument I have a SR locking-table for Seaton, which confirms that ALL the FPLs there locked both ways :-) As also did no 13 at Tipton St John (FPL on the facing point for the siding off the Up loop).

[RailWest]

On the LMR where an FPL was provided it would stand in with the lever normal. The operation was pull 1 to release the frame, pull 2 to unbolt the points, pull 3 to reverse the points. This way the frame release could not be given back to the controlling box without the points being bolted.

On the L&SWR/SR, and also the GWR, where it was the usual (but not universal) practice for FPL levers in signal-boxes to stand normally 'out' - ie pull the lever to bolt the point - it was still the practice in normally-unmanned GFs to FPLs to be normally 'in'.

[Nearholmer]

The SR might have concluded that having designs and components (lock-stretchers with slots in different places? I’m not a signalling Engineer, so defer to those who are) for the various permutations of FPL was pointless and expensive, when having a single design that covered the ‘worst case’ was easier, and probably cheaper in the round.

[RailWest]

The SR might have concluded that having designs and components (lock-stretchers with slots in different places? I’m not a signalling Engineer, so defer to those who are) for the various permutations of FPL was pointless and expensive, when having a single design that covered the ‘worst case’ was easier, and probably cheaper in the round.

 

In essence a FPL stretcher is either a 1-hole or a 2-hole version. Clearly with the former the hole may be in either the LH or RH position, depending for which route you wished to lock.

 

Having (fortunately!) never had to cut the necessary 'ports' myself, I'm only guessing here but my suspicion is that - given the fine tolerances required - the port(s) would have been cut on site once the pointwork had been assembled, in which the 'single design' hypothesis could not apply. 

 

Can anyone clarify please?

[Nearholmer]

Oh.

 

I’d assumed the holes were in a standard place, machined in a workshop, and that any ‘fitting’ was done by shimming/shifting the thingamajig that holds/guides the locking tongue.

 

There’s a large scale working model of one in the office where I work periodically, and that doesn’t work because it’s all of of adjustment .... I keep getting tempted to bring it home and sort it out.

[The Stationmaster]

On the LMR where an FPL was provided it would stand in with the lever normal. The operation was pull 1 to release the frame, pull 2 to unbolt the points, pull 3 to reverse the points. This way the frame release could not be given back to the controlling box without the points being bolted.

 

Same on the Western except only 2 levers were normally used with an Annet's key to unlock the FPL lever then as above.  But on the Western numerous (the majority?) older engine release points in bay platforms etc didn't have an FPL.

 

Normal Western practice that I observed from the 1960s onwards was to cut the FPL port(s) on site.

[pete_mcfarlane]

The more Southern branch terminals I have looked at, the more I have come to the conclusion that there was no laid down standard for how the engine release crossover was worked 

When designing the signalling for my fictional ex-SER terminus, I got the distinct impression from studying the various SER branch lines that they didn't have any set standards, and simply let whichever signalling company put in the lowest bid do things in their preferred way. 

[PaulRhB]

As promised here is a roughly drawn track diagram. I haven't put any signalling on it yet.

 

blackhurst_trackplan_2018_25%.png

The Signalbox could be moved to the other side, much like Swanage railway has done in preservation days. There are examples of SR boxes, Marchwood still just hanging on, with a mix of mechanical and point machines but only where the throw is too long for rodding and it didn't make sense to add a second box.

[RailWest]

Some entirely random thoughts :-)

 

1. I would omit the FPL on the release crossover.

2. I see no obvious reason for a FPL on the trap at the exit from the spur off the Bay.

3. Assuming that the Bay is a passenger line (?), then unless you plan to use it just as a siding for most of the time then I would suggest that the point leading into the spur should lie normally towards the main line not the spur.

4. Any reason why the SB is not in the space at the end of the platforms ?

[PaulRhB]

4. Any reason why the SB is not in the space at the end of the platforms ?

I agree and if the layout is still being built easy to do but probably because many model platforms are too narrow and leave insufficient space unless you 'wiggle' round the the box? Edited January 26, 2018 by PaulRhB

[Geep7]

I agree and if the layout is still being built easy to do but probably because many model platforms are too narrow and leave insufficient space unless you 'wiggle' round the the box?

Unfortunately the layout is already built, but yes, the platforms are a bit on the narrow side. Would have loved to have made them wider.

 

Here is a photo of the current arrangement at the platform ends and station throat.

 

 

The current thought is to move the signal box to beside where the mermaid wagons are, and put a small substation where the signal box currently is.

[Oldddudders]

Putting the box on the platform end would also compromise platform length a bit. Never enough length on our models!

[RailWest]

I would suggest that the bracket signal in your photo needs to be further back up the ramp. In its current position it would appear that any train stood at it in the main platform would foul the crossover to the yard, while any in the Bay would be stood on the (imaginary) locking bar or track-circuit for the FPL, so you wouldn't be able to set the road out.  But it may be my mis-interpretation from the camera's angle of view.....

[TheSignalEngineer]

In essence a FPL stretcher is either a 1-hole or a 2-hole version. Clearly with the former the hole may be in either the LH or RH position, depending for which route you wished to lock.

 

Having (fortunately!) never had to cut the necessary 'ports' myself, I'm only guessing here but my suspicion is that - given the fine tolerances required - the port(s) would have been cut on site once the pointwork had been assembled, in which the 'single design' hypothesis could not apply. 

 

Can anyone clarify please?

The lock stretcher came with the two holes partly cut in the middle of the two positions required. This was to allow a hacksaw blade to be put in horizintally when the two sidea of the required holes had been marked actually fitted to the points and then cut vertically. 

[TheSignalEngineer]

Some entirely random thoughts :-)

 

1. I would omit the FPL on the release crossover.

2. I see no obvious reason for a FPL on the trap at the exit from the spur off the Bay.

3. Assuming that the Bay is a passenger line (?), then unless you plan to use it just as a siding for most of the time then I would suggest that the point leading into the spur should lie normally towards the main line not the spur.

4. Any reason why the SB is not in the space at the end of the platforms ?

2. Agreed

3. Better from the interlocking point of view to have the Bay end double ended with the Main line and the Spur trap as a separate end.

[Geep7]

I would suggest that the bracket signal in your photo needs to be further back up the ramp. In its current position it would appear that any train stood at it in the main platform would foul the crossover to the yard, while any in the Bay would be stood on the (imaginary) locking bar or track-circuit for the FPL, so you wouldn't be able to set the road out. But it may be my mis-interpretation from the camera's angle of view.....

There is plenty of clearance on the main platform for a train to sit at the signal and a train to enter the good loop. However I take your point about the signal being too far past the point for the siding off the bay. Perhaps having a bracket starter isn't the right thing, and I should have 2 separate starter signals.

[Geep7]

There is plenty of clearance on the main platform for a train to sit at the signal and a train to enter the good loop. However I take your point about the signal being too far past the point for the siding off the bay. Perhaps having a bracket starter isn't the right thing, and I should have 2 separate starter signals.

Actually i've just been and had another look, and the bracket signal could move another inch or so towards the platform onto the platform ramp, thereby clearing the point to the stabling siding.

[Mike Storey]

This may help. The diagram of the signalling at Sheerness in 1961, at electrification and installation of MAS, has many similarities to your layout. The actual layout differs little from the pre-electrified version. 

 

Sheerness signalling diagram 1961.docx

 

You will notice that the centre road has GF operated crossovers at the stops ends, neither with an FPL. 1 for release and 2 and 3 for each pair of points. The remainder of points within the station area were motorised and operated from Sittingbourne panel.

 

Whereas the GF operated junction at the left of the diagram, to release trains from the Westminster Straight (from the Dockyard), does include a FPL.

 

 

[RailWest]

This may help. The diagram of the signalling at Sheerness in 1961, at electrification and installation of MAS, has many similarities to your layout. The actual layout differs little from the pre-electrified version. 

 

>>>You will notice that the centre road has GF operated crossovers at the stops ends, neither with an FPL. 1 for release and 2 and 3 for each pair of points. .....

 

Actually, if you look closely it has 4 levers. 1 is the release for 2, 4 is the release for 3. Think of it as two separate GFs - one for each platform - combined in one frame - with the appropriate interlocking between them.

 

>>>Whereas the GF operated junction at the left of the diagram, to release trains from the Westminster Straight (from the Dockyard), does include a FPL....

 

Which is what one would expect, given that it is a facing point on a passenger line :-)

Edited January 30, 2018 by RailWest

[Grovenor]

The unusual features at Sheerness are the trap points on the platform ends, what was the reason for those?

Regards

[73c]

Of interest

http://www.railwaysarchive.co.uk/documents/MoT_Sheerness1971.pdf

[TheSignalEngineer]

The unusual features at Sheerness are the trap points on the platform ends, what was the reason for those?

Regards

Possibly because any train passing a platform signal at danger will end up on a single line, so could go head on into an approaching train.