Jump to content

facing point lock operation


Recommended Posts

A question for the signal experts.

 

When a point has a facing point lock on a separate lever is it typical that the lock lever has to be pulled in order to pull the point? I thought that was the way it worked - point usually locked by the lock, pull lock off, pull point off, return lock etc. I implemented the locking on my test frame that way but it was commented on implying that the point would normally be unlocked and then the locking lever pulled to lock it.

 

Which way around was correct? did it vary between the different frame manufacturers and/or regions and dates?

 

Your expert opinions please?

 

BTW the locking on my frame is all implemented via software so if I have it the wrong way around I only need to change a few lines of code and not worry about remaking physical locking bars.

 

thanks

David Barham

Link to post
Share on other sites
  • RMweb Gold

Normal practice as I understand it is that the point would be unlocked with the lever back in the frame, and the locking lever would have to be pulled before the interlocking would allow signals to be cleared. Normal state would be for the points to be unlocked.

 

Andi

Link to post
Share on other sites
Guest stuartp

Normal practice as I understand it is that the point would be unlocked with the lever back in the frame, and the locking lever would have to be pulled before the interlocking would allow signals to be cleared. Normal state would be for the points to be unlocked.

 

That's my experience. For reasons I [edit - must have known at the time but have clearly since forgotten !] with no train signalled the route was normally left locked (i.e. with the levers reversed) in the boxes I worked. Bruises from walking into FPL levers were an occupational hazard.

Link to post
Share on other sites

There are places where the FPL lever locks the points in the frame though personally i'm not a fan of this. Anything i have designed always lock the points with the lever reversed. One example that springs to mind is Reedham Junction, Norfolk where the FPL lever locks one set of switches out of the frame an another when in. I'll see if i can find a photo of the pull plate..

Link to post
Share on other sites
  • RMweb Gold

There are places where the FPL lever locks the points in the frame though personally i'm not a fan of this. Anything i have designed always lock the points with the lever reversed. One example that springs to mind is Reedham Junction, Norfolk where the FPL lever locks one set of switches out of the frame an another when in. I'll see if i can find a photo of the pull plate..

There isn't a hard-and-fast rule about this. One has seen plenty of signalling diagrams where the legend states "FPLs stand normally out" but a few where the opposite is true. It isn't an issue - the signalman on duty will have had training in that box and been passed out as competent, so will know how the arrangements are. It's no different from upper and lower quadrant signals - both work and are equally effective.

Link to post
Share on other sites
  • RMweb Gold

As as has been said the lever is normally reversed to lock the point, after the point has been set in the correct position, locking with the lever normal is uncommon (compared with the number that were locked by reverse) and typically was used at double junctions with movable angles (switch diamonds) to lock the "facing" parts of the angle.

 

That's my experience. For reasons I never did fathom, with no train signalled the route was normally left locked (i.e. with the levers reversed) in the boxes I worked. Bruises from walking into FPL levers were an occupational hazard.

 

Block regs require all points to be set and locked ... ;)

 

BTW the locking on my frame is all implemented via software so if I have it the wrong way around I only need to change a few lines of code and not worry about remaking physical locking bars.

 

If you like, you could post the plan for comment :)

Link to post
Share on other sites
Guest stuartp

Thanks Dave. Clearly the Mek Pak fumes have been having an effect if I'm forgetting things that basic ! blink.gif

 

And apparently there are still some Economical Facing Point Locks in operation out there that do the whole thing with just one lever. Much easier!

 

Until they go wrong and you have to stare at the thing for ten minutes just to work out which bit of linkage is supposed to move what. Appleby PWay used to skip this step and just beat it with a keying hammer until something moved or fell off.

Link to post
Share on other sites
  • RMweb Gold

And apparently there are still some Economical Facing Point Locks in operation out there that do the whole thing with just one lever. Much easier!

 

Are you sure ? - I thought Appleby was the last and I believe thats gone.

Link to post
Share on other sites
  • RMweb Gold

And apparently there are still some Economical Facing Point Locks in operation out there that do the whole thing with just one lever. Much easier!

 

It is also my understanding that the last one on the national network was at Appleby; however they are in use on a number of preserved/heritage lines.

 

I would regard 'easier' as a debatable word in relation to economical FPLS as some designs could be very difficult to set up and adjust, however the Midland Railway seemed quite happy with them so someone must have found the trick.

Link to post
Share on other sites

I know - thats what I said but in a gentle way :unsure:

 

How sad!

 

The last one on the Vale of Rheidol failed rather spectacularly leaving an up passenger spread all over the station throat at Devil's Bridge.

 

On a related topic, does anyone know the true story of what caused the software(?) fp lock to fail on the ng at Blaenau just after the new system there was installed? I never heard the full story and believe it was, shall we say, kept rather quiet at the time.

Link to post
Share on other sites

How sad!

 

The last one on the Vale of Rheidol failed rather spectacularly leaving an up passenger spread all over the station throat at Devil's Bridge.

 

On a related topic, does anyone know the true story of what caused the software(?) fp lock to fail on the ng at Blaenau just after the new system there was installed? I never heard the full story and believe it was, shall we say, kept rather quiet at the time.

 

Errmm what software???

 

The approach to BF was controlled via relay interlocking never an SSI in sight, and as i spent many hours in the cabinets making it work and trying to replicate the problem without success i can speak with some authority and the system is now mothballed

 

What I can tell you is that it is now working from a ground frame.

Link to post
Share on other sites

Errmm what software???

 

The approach to BF was controlled via relay interlocking never an SSI in sight, and as i spent many hours in the cabinets making it work and trying to replicate the problem without success i can speak with some authority and the system is now mothballed

 

What I can tell you is that it is now working from a ground frame.

 

Interesting - thanks!

Link to post
Share on other sites

Errrrm, at the risk of heading mildly off topic..... can anyone post a picture of a more antique economical FPL setup.

I am intrigued.

My grandfather, before heading into telecoms, was a fully trained mechanical S&T apprentice, joining in '36. even today when given scheme queeries, economical FPLs are brought up as an example of how to.

Perhaps one of us with a more historical bias might give a synopsis of the locking bar versus the fpl and the economical FPL, and the regs governing usage and installation.

Link to post
Share on other sites
  • RMweb Gold

Knew i had a photo of the one at Appleby

 

Why does that remind me of the operating mech for the Hornby points I had on my train set? Great photo though, very interesting.

 

Andi

Link to post
Share on other sites
  • RMweb Gold

Errrrm, at the risk of heading mildly off topic..... can anyone post a picture of a more antique economical FPL setup.

I am intrigued.

My grandfather, before heading into telecoms, was a fully trained mechanical S&T apprentice, joining in '36. even today when given scheme queeries, economical FPLs are brought up as an example of how to.

Perhaps one of us with a more historical bias might give a synopsis of the locking bar versus the fpl and the economical FPL, and the regs governing usage and installation.

 

I seem to recollect that MickNich might have posted one in the past - no doubt he'll look in on this thread before long and we might get one (again).

 

There is no question of 'locking bar versus the fpl' as facing points in lines used by passenger trains were required to have both (or a track circuit in lieu of a locking bar). Thus a further complexity when an economical fpl was used was the need to incorporate the locking bar - and it was the locking bar which was required to drive the fpl bolt (although some installations I believe applied that requirement in an 'interpreted' manner.

Link to post
Share on other sites

locking bars may also be called fouling bars in some areas. The ones I installed were use to ensure that both the main route was bolted normal for passenger operation and that when shunting the train had gone past the points far enough to allow them to be safely thrown.

Link to post
Share on other sites
  • RMweb Gold

locking bars may also be called fouling bars in some areas. The ones I installed were use to ensure that both the main route was bolted normal for passenger operation and that when shunting the train had gone past the points far enough to allow them to be safely thrown.

 

Fouling/detection bars are not necessarily the same thing as facing point bar.

Link to post
Share on other sites
  • RMweb Gold

locking bars may also be called fouling bars in some areas. The ones I installed were use to ensure that both the main route was bolted normal for passenger operation and that when shunting the train had gone past the points far enough to allow them to be safely thrown.

 

 

The purpose of a fouling bar is to detect the presence of rail vehicles at a Fouling Point and they were used in situations where the Signalman had a poor view of a Fouling Point and, I quote, '...where it is difficult for a signalman to estimate clearance... in order to define the fouling points of junctions, siding connections, crossings etc.'. Fouling Bars were interlocked with signals and were completely separate from anything to do with the operation of points.

 

They (had) visual similarites to a Facing point Locking bar but that was where any connection between them ended.

Link to post
Share on other sites

Hate to differ but the FPL at the current Cheddleton station on the CVR and those at Leek Brook Junction were driven from the fouling bars.

 

This was a common practice on the old North Staffs Systems hence my comment about locking bars and fouling bars.

Link to post
Share on other sites

Not the worlds best image and you can just about make out the fouling/drive bars, fpl etc.

 

I have highlighted the drive end and the bolt fpl end. In order for the fpl to be moved the fouling/locking bar bar had to move up and over past the rail head.

post-8268-128051897268_thumb.jpg

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.