Point numbering conventions & use of catch points

Any questions about designing a model railway layout or problems with track work.
ShinyShoe
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Point numbering conventions & use of catch points

Postby ShinyShoe » Tue Jan 11, 2011 12:20 am

I'm wondering if there is a point numbering convention? i.e. left to right etc?

My schematic is below:

Image

Is it OK to number them like this? (8,9,10 are catch points)

Secondly - how should catch points be wired up? Not sure I entirely understand how they are set up! From what I understand they exist to stop wagons on the sidings reaching the mainline where a passenger train could crash into them.

So in my niave head if the main line is operational then the catch point must be set the 'catch' but if the main line is set to ?danger or ???caution then the catch could be open. BUT can they somehow be wired up to either the other points or signals to give them automatic function?

Anyone got any thoughts on signalling?

m8internet
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Re: Point numbering conventions & use of catch points

Postby m8internet » Tue Jan 11, 2011 3:55 am

There is no real numbering convention I am aware of
Numbering tends to start from one direction and end at the other

Catch point No 10 looks acceptable

There is no need for two catch points No 8 and 9
However, if you want to include a catch point, then in is a right hand (No 8) and positioned between No 5 and No 7
The danger with No 9 is that train derails and then conflicts with a train passing on the track beside it

Catch points can be linked to the main point with interlocking
However, like all other points, are wired separately
This allows the signaller to move each on its own and to then advise the driver to perform a visual inspection that all points are set correctly and to pass the red signal
Glasgow Queen Street Model Railway layout : modern image N gauge using DCC

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stuartp
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Re: Point numbering conventions & use of catch points

Postby stuartp » Tue Jan 11, 2011 10:29 am

Trap* points would normally be co-acting with the points giving access to that siding - i.e. on your diagram 2 and 10 would be worked together (and would be numbered 2A and 2B or 10A and 10B usually, with the 'A' end usually being nearest the box). Like m8 says there is no need for separate traps 8 and 9 unless there was a restricted space issue, a single trap between points 5 and 7 would do the same job.

Likewise your crossovers would be numbered 1A/1B and 3A/3B with both ends worked off the same lever/button/switch.

The points take the number of the controlling lever/button/switch in the controlling signal box. How these were numbered depends on who built the box (i.e. which railway company or signalling contractor) and the exact order would depend on what needed to be interlocked with what. Interlocking on a mechanical frame was done with sliding bars and tappets connected to the levers and there are only so many ways you can arrange those without tying yourself in knots but each installation was unique.

Lets say your signalbox is at the bottom of your diagram. A typical layout would have all the signal levers for trains approaching from the left at the left hand end of the frame, and those for trains approaching from the right at the right hand end. In the middle would be points (and facing point locks),shunting signal levers, detonator places, slots and releases etc. That's just one example, another company might have interspersed the point levers in amongst the signals. Have a look on signalbox.org at some of the track diagrams, you can generally work out roughly what was going on even if you don't get some of the subtleties.

Power signalling is a bit more confused as the controls are just switches and are not constrained by having to be mechanically locked by each other, and on a more modern panel the route is normally set by pressing a button at each end rather than using individual switches, or by clicking a cursor on a screen. But if you're on an older OCS (One Control Switch) panel then the same rule applies - Number 'X' points are worked by number 'X' button/switch.

Signalling your diagram is a bit awkward as there are a lot of facing connections. Not impossible and not unknown but it adds more facing point locks and increases costs. If you could make it a mirror image (either way) it would be simpler. It would also be possible to shunt the sidings without having to run round every time. Did you have a particular era/location in mind, or even just semaphore/colour light ?

I use the word 'normally/usually' deliberately - there were always exceptions.

[* Catch points are generally sprung points on running lines designed to stop wrong-direction runaways. As the exits from these sidings would be controlled by signals and the points are worked, I'd consider these trap points. The nomenclature varies across eras and regions though.]
Portwilliam - Southwest Scotland in the 1960s, in OO - http://stuart1968.wordpress.com/

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Bufferstop
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Re: Point numbering conventions & use of catch points

Postby Bufferstop » Tue Jan 11, 2011 12:39 pm

If you wan't a ground-up intro to signalling of the mechanical/electro-mechanical varieties, try downloading the free "SigScribe" software from Modratec. Its examples give step by step explanations in both using the software and the prototype methods applicable to typical model situations. They would obviously like you to carry on and eventually order a full lever and lockingframe kit from them, but there's no pressure to do so.
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poliss
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Re: Point numbering conventions & use of catch points

Postby poliss » Tue Jan 11, 2011 1:50 pm

Trap points

(23)Where sidings or freight only lines converge on passenger lines, and any overrun from such lines might foul a passenger line, trap points should be provided to derail vehicles.
Trap points should be located and means provided to guide and arrest derailed vehicles away from the passenger lines, structures and any other hazards.

(24) Trap points with an arresting system may be necessary on passenger lines at:
(a) the entrance to, and on passing loops within, single lines where the overlap beyond the protecting signal is substandard;
(b) the approach to swing or moveable bridges; and
(c) stations on gradients steeper than 1 in 500 where vehicles are left unattended.

Catch points
(25) Catch points should be provided to derail vehicles running away backwards, and located so that vehicles are not directed towards another railway or another danger. They are not required if all trains using the line are fully-fitted with an automatic brake, or if only a few trains are not so fitted and special arrangements can be made to hold a following train in a place of safety until a preceding unfitted train has cleared the gradient.

Note 1: Consideration should be given on passenger lines on rising gradients to arresting vehicles which may have become divided from their train.

Note 2: Similar provision should be provided on freight lines where a runaway vehicle could foul a passenger line.

http://www.rail-reg.gov.uk/upload/pdf/r ... rstrct.pdf

ShinyShoe
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Re: Point numbering conventions & use of catch points

Postby ShinyShoe » Tue Jan 11, 2011 7:22 pm

m8internet wrote:There is no need for two catch points No 8 and 9

I know - they are done like that because of track length issues (the schematic doesn't make that apparent).
However, if you want to include a catch point, then in is a right hand (No 8) and positioned between No 5 and No 7
The danger with No 9 is that train derails and then conflicts with a train passing on the track beside it

They are all set as R hand - again a schematic issue.

Catch points can be linked to the main point with interlocking
However, like all other points, are wired separately
This allows the signaller to move each on its own and to then advise the driver to perform a visual inspection that all points are set correctly and to pass the red signal

You've lost me! Assuming I'm just using SPDT switches?

ShinyShoe
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Re: Point numbering conventions & use of catch points

Postby ShinyShoe » Tue Jan 11, 2011 7:56 pm

stuartp wrote:Trap* points would normally be co-acting with the points giving access to that siding - i.e. on your diagram 2 and 10 would be worked together (and would be numbered 2A and 2B or 10A and 10B usually, with the 'A' end usually being nearest the box).

Thanks. So in other words when 2A is pointing up the siding then 2B is set not to trap?

Likewise your crossovers would be numbered 1A/1B and 3A/3B with both ends worked off the same lever/button/switch.

Its a double switch. So has 4 states so needs two switches?

Power signalling is a bit more confused as the controls are just switches and are not constrained by having to be mechanically locked by each other, and on a more modern panel the route is normally set by pressing a button at each end rather than using individual switches, or by clicking a cursor on a screen. But if you're on an older OCS (One Control Switch) panel then the same rule applies - Number 'X' points are worked by number 'X' button/switch.

Oh... I should have said - modern day layout fully electronic.
I'm quite happy to dabble with electronics or small electrics so systems can be configured to force certain conditions by electronically interlocking (I think!) using switches in series?

Signalling your diagram is a bit awkward as there are a lot of facing connections. Not impossible and not unknown but it adds more facing point locks and increases costs. If you could make it a mirror image (either way) it would be simpler.

Depends how much harder... the cork is layed ;-)
Still taking my time to get used to crossing lights at danger and needing things like 3 sets of lights in advance! Clearly I probably can't have all of them...
It would also be possible to shunt the sidings without having to run round every time. Did you have a particular era/location in mind, or even just semaphore/colour light ?

In essence its a inglenook (using the mainline as the headshunt) and a slightly modified timesaver squezed into one. I haven't yet done any test tracking of the timesaver but the inglenook works quite well as it is.

To the right of the track there will be a second module with a station on it etc but thats far from designed. the the left the mainlines lead off (to a fiddle yard!)

[* Catch points are generally sprung points on running lines designed to stop wrong-direction runaways. As the exits from these sidings would be controlled by signals and the points are worked, I'd consider these trap points. The nomenclature varies across eras and regions though.]

someone shouls tell peco!

m8internet
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Re: Point numbering conventions & use of catch points

Postby m8internet » Tue Jan 11, 2011 8:19 pm

I am personally not bothereed whether they are called catch, trap, or bingo points
We all know what they look like and their purpose

Peco supply two versions in N gauge
The code 80 version, which I am using, is rather basic
The code 55 version is much more realistic

However, in their OO gauge range both are basic

Perhaps it's time to replace that image with a more correct version and the updated point numbers
1 => 1A
6 => 1B

3 => 3A
4 => 3B

Move 8 to between 5 and 7
Remove 9
Glasgow Queen Street Model Railway layout : modern image N gauge using DCC

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stuartp
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Re: Point numbering conventions & use of catch points

Postby stuartp » Tue Jan 11, 2011 8:44 pm

ShinyShoe wrote:
stuartp wrote:Trap* points would normally be co-acting with the points giving access to that siding - i.e. on your diagram 2 and 10 would be worked together (and would be numbered 2A and 2B or 10A and 10B usually, with the 'A' end usually being nearest the box).

Thanks. So in other words when 2A is pointing up the siding then 2B is set not to trap?


Exactly.

ShinyShoe wrote:
stuartp wrote:Likewise your crossovers would be numbered 1A/1B and 3A/3B with both ends worked off the same lever/button/switch.

Its a double switch. So has 4 states so needs two switches?


Haven't a clue sorry, I can just about wire up a Peco point motor. I was referring to the method of control in the signal box - both ends of the cross-over would be worked off the same lever or button - the signalman would operate one control and the A and B ends would both move at the same time.

In essence its a inglenook (using the mainline as the headshunt) and a slightly modified timesaver squezed into one


Ooh, so it is - clever ! I'll have a go at signalling it 'as is' then when I get five minutes.

M8 - I wasn't having a go, just explaining why I had referred to trap points when ShinyShoe had referred to catch points all the way through. It was drummed into me at signalling school - you got a lever collar chucked at you for getting them the wrong way round.
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ShinyShoe
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Re: Point numbering conventions & use of catch points

Postby ShinyShoe » Tue Jan 11, 2011 8:55 pm

m8internet wrote:However, in their OO gauge range both are basic

I'm using Code 75 on OO

Hopefully this is the corrected version. It still has two trap points attached to 7 - thats a space issue, which I know may not be likely on the prototype but is absolutely necessary and as its on a gradient too the trap points are more than just a pretty feature!

Image

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Free_at_last
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Re: Point numbering conventions & use of catch points

Postby Free_at_last » Tue Jan 11, 2011 11:08 pm

stuartp wrote:
Likewise your crossovers would be numbered 1A/1B and 3A/3B with both ends worked off the same lever/button/switch.
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m8internet
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Re: Point numbering conventions & use of catch points

Postby m8internet » Tue Jan 11, 2011 11:35 pm

stuartp wrote:M8 - I wasn't having a go, just explaining why I had referred to trap points when ShinyShoe had referred to catch points

Not at all, I still refer to them as catch points even though I know I should refer to either correctly
Personally, I blame Peco for not describing them as "catch / trap points"
However, the main difference is their placement
Equally on my layout I don't actually need some of them but I think it is a nice touch
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m8internet
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Re: Point numbering conventions & use of catch points

Postby m8internet » Tue Jan 11, 2011 11:37 pm

ShinyShoe wrote:It still has two trap points attached to 7 - thats a space issue

Even with a space issue only one is required as advised above
The revised diagram has a further conflict as 7C throws a derailed train into the other track; it really needs to be a sterile area
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Bufferstop
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Re: Point numbering conventions & use of catch points

Postby Bufferstop » Tue Jan 11, 2011 11:50 pm

m8internet wrote:The revised diagram has a further conflict as 7C throws a derailed train into the other track; it really needs to be a sterile area

But would 7 need protection if it was not on a passenger carrying line?
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ShinyShoe
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Re: Point numbering conventions & use of catch points

Postby ShinyShoe » Wed Jan 12, 2011 12:26 am

freeatlast
Many thanks for the revised drawing - wasn't undderstanding what you meant by 1 and 6 - all became clear when you changed it!

3A and 4 may not be right. Its a double switch. So bear with me on this:

A train coming along the top main line from the right passes through 3B and can either proceed stright or turn. Proceeding straight should mean that 3A is set straight too. Turning means the train is now aproaching 3A. 3A could be set straight (to siding -7) or to turn towards 1A. So 3A can't be dependant on 3B.

A train coming from Lower Main Line from Right goes through 4. If 4 is set straight, 3B must be set straight. If 4 is turned 3B should be set straight. (On that basis no matter where 4 is, 3B is straight?? But what I mean is is 4 is set for a train to come through 3B must be straight. If 3B is set turned then no train can go through 4.)
If 4 is straight, 3A must be straight.

What I'm getting at is should 4 be 3C?




m8internet wrote:Even with a space issue only one is required as advised above
The revised diagram has a further conflict as 7C throws a derailed train into the other track; it really needs to be a sterile area

The problem is (and I will double check before track is set down) that putting a trap point between 7A and 3A moves 7A by 100mm and causes an issue. (7A and 3A are directly connected there is no straight between them.)

Derailing onto the siding is the best of a bad option. But using two traps may cause an interlock issue? Should both traps be open?


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