https://irse.signalpost.org/ Wed, 12 Aug 2026 03:14:39 +0000 MyBB https://irse.signalpost.org/showthread.php?tid=2433 Fri, 19 Feb 2021 10:48:28 +0000 ledwardz]]> https://irse.signalpost.org/showthread.php?tid=2433
not an exam question, just after some general info.

Can someone tell me what a point backdrive D switch is?

What is the point backdrive used for and how this relates to the D switch?

Thanks in advance for any info.

Lee.]]>
not an exam question, just after some general info.

Can someone tell me what a point backdrive D switch is?

What is the point backdrive used for and how this relates to the D switch?

Thanks in advance for any info.

Lee.]]> https://irse.signalpost.org/showthread.php?tid=2352 Sat, 20 Apr 2019 20:20:33 +0000 AshF91]]> https://irse.signalpost.org/showthread.php?tid=2352 https://irse.signalpost.org/showthread.php?tid=2243 Sun, 10 Dec 2017 07:47:43 +0000 PJW]]> https://irse.signalpost.org/showthread.php?tid=2243 https://irse.signalpost.org/showthread.php?tid=2213 Sun, 17 Sep 2017 15:36:37 +0000 mattslade222]]> https://irse.signalpost.org/showthread.php?tid=2213
I have been looking at past questions around points maintenance procedures. I don't have any hands on experience apart from in training schools so am struggling to visualize what exactly is being measured and why during the FWC, FWP and RSO measurements taken during point inspections.

Here is my understanding - please correct or confirm if you wouldn't mind.

Residual Switch Opening (RSO) - the gap between the switch blade and the stock rail in the closed position. Shud be nominally around 1.5mm, between the lock stecher bar to the send P-way stretcher bar. The Facing Point Lock test sort of checks this at the point toe, as the 1.5mm should allow lock to engage, where as 3.5mm should fail.

Free Wheel Clearance (FWC) - Is the gap between the stock rail and open switch blade. We measure this for the length of the moveable point and ensure the minimum distance is greater than 50mm (some exceptions apply based on switch type and track speed)

Free Wheel Passage (FWP) - Is the distance from the outside edge of an open switch blade to the inside edge of the closed switch blade. This should be 1387mm for the length of the movable points, which I believe is derived from the track gauge - the FWC.

Switch opening - Is the gap between the open switch blade and the stock rail, for the wheel flange to pass through, this should be 102mm -120mm, usually.

This is based on the an old version of the SMS I found, looking at various parts. I have a few questions:

1) Is my understanding correct!? 
2) At the point toe what is the difference between the Free Wheel Clearance and Switch Opening, are they not the same there?
2) The FWP, what's the impact of this not being set correctly? Does it though off the FWC which could result in a derailment?]]>
I have been looking at past questions around points maintenance procedures. I don't have any hands on experience apart from in training schools so am struggling to visualize what exactly is being measured and why during the FWC, FWP and RSO measurements taken during point inspections.

Here is my understanding - please correct or confirm if you wouldn't mind.

Residual Switch Opening (RSO) - the gap between the switch blade and the stock rail in the closed position. Shud be nominally around 1.5mm, between the lock stecher bar to the send P-way stretcher bar. The Facing Point Lock test sort of checks this at the point toe, as the 1.5mm should allow lock to engage, where as 3.5mm should fail.

Free Wheel Clearance (FWC) - Is the gap between the stock rail and open switch blade. We measure this for the length of the moveable point and ensure the minimum distance is greater than 50mm (some exceptions apply based on switch type and track speed)

Free Wheel Passage (FWP) - Is the distance from the outside edge of an open switch blade to the inside edge of the closed switch blade. This should be 1387mm for the length of the movable points, which I believe is derived from the track gauge - the FWC.

Switch opening - Is the gap between the open switch blade and the stock rail, for the wheel flange to pass through, this should be 102mm -120mm, usually.

This is based on the an old version of the SMS I found, looking at various parts. I have a few questions:

1) Is my understanding correct!? 
2) At the point toe what is the difference between the Free Wheel Clearance and Switch Opening, are they not the same there?
2) The FWP, what's the impact of this not being set correctly? Does it though off the FWC which could result in a derailment?]]> https://irse.signalpost.org/showthread.php?tid=1928 Tue, 26 May 2015 14:01:22 +0000 SusannahW]]> https://irse.signalpost.org/showthread.php?tid=1928 I’ve come across the following in Network Rail standard SSI/8500/D(1), section 4.1 “Motor Drive Outputs”. The section details the motor drive outputs of points object controllers for SSI.
“A motoring up facility is also provided in the Module which operates in the event of detection loss without any change in the points control command from the signalling.”
So I’m taking this to me that in event that detection is lost without a command from the interlocking the points machine redrives the points to regain detection with no additional command to do so from the interlocking. I have a few questions about this:

Does it do this even if there is a train in section or even on the points?

What is the history behind this, is there an incident which occurred that meant this had to be introduced?

Where the points machine is not controlled by SSI is this function still present?

Many thanks for any help you might be able to give with this issue.]]> I’ve come across the following in Network Rail standard SSI/8500/D(1), section 4.1 “Motor Drive Outputs”. The section details the motor drive outputs of points object controllers for SSI.
“A motoring up facility is also provided in the Module which operates in the event of detection loss without any change in the points control command from the signalling.”
So I’m taking this to me that in event that detection is lost without a command from the interlocking the points machine redrives the points to regain detection with no additional command to do so from the interlocking. I have a few questions about this:

Does it do this even if there is a train in section or even on the points?

What is the history behind this, is there an incident which occurred that meant this had to be introduced?

Where the points machine is not controlled by SSI is this function still present?

Many thanks for any help you might be able to give with this issue.]]> https://irse.signalpost.org/showthread.php?tid=1926 Mon, 18 May 2015 01:55:52 +0000 asrisaku]]> https://irse.signalpost.org/showthread.php?tid=1926
Another attempt for point machine question. Any comment is welcome!

Best regards
Arnut]]>
Another attempt for point machine question. Any comment is welcome!

Best regards
Arnut]]> https://irse.signalpost.org/showthread.php?tid=1923 Mon, 04 May 2015 10:09:06 +0000 asrisaku]]> https://irse.signalpost.org/showthread.php?tid=1923
I have tried to understand four types of point machines. I am not sure that I can have a real understanding about them. So if any one of you gives me any comment, it would be really nice to me.

Most point machines I have no chance to see them with the real move.

The detection mechanism for style 63 looks unclear to me. Any clear diagram, that would be so good for me.

Thanks and regards
Arnut]]>
I have tried to understand four types of point machines. I am not sure that I can have a real understanding about them. So if any one of you gives me any comment, it would be really nice to me.

Most point machines I have no chance to see them with the real move.

The detection mechanism for style 63 looks unclear to me. Any clear diagram, that would be so good for me.

Thanks and regards
Arnut]]> https://irse.signalpost.org/showthread.php?tid=1891 Wed, 11 Mar 2015 01:16:43 +0000 asrisaku]]> https://irse.signalpost.org/showthread.php?tid=1891
May I have any comment on my attempt?

I am not sure that I answered what the question asks.

I tried to use the diagrams to provide the answer and struggled with the wordy explanation.

Could you please point out what I can add more or any serious mistake?

Thanks in advance

Best regards
Arnut]]>
May I have any comment on my attempt?

I am not sure that I answered what the question asks.

I tried to use the diagrams to provide the answer and struggled with the wordy explanation.

Could you please point out what I can add more or any serious mistake?

Thanks in advance

Best regards
Arnut]]> https://irse.signalpost.org/showthread.php?tid=1848 Sun, 28 Sep 2014 13:48:37 +0000 Savitha]]> https://irse.signalpost.org/showthread.php?tid=1848 what will be the advantages of sequential operation of point ends over parallel operation of point ends?.
if both the ends of points are operated simultaneously, the response time will be less. but sequential operation of point ends is preffered. why?

regards,
savitha]]> what will be the advantages of sequential operation of point ends over parallel operation of point ends?.
if both the ends of points are operated simultaneously, the response time will be less. but sequential operation of point ends is preffered. why?

regards,
savitha]]> https://irse.signalpost.org/showthread.php?tid=1550 Mon, 09 Dec 2013 05:57:56 +0000 nagaraju.a@etoerail.com]]> https://irse.signalpost.org/showthread.php?tid=1550
I just want to have glance regarding existing point machines used in LUL like Chair lock, Clamp lock, 4 foot and 6 foot. Its specification and right place to use with circuits, if available. Any comments and answers, please welcome.

Regards,
A Naga Raju]]>
I just want to have glance regarding existing point machines used in LUL like Chair lock, Clamp lock, 4 foot and 6 foot. Its specification and right place to use with circuits, if available. Any comments and answers, please welcome.

Regards,
A Naga Raju]]> https://irse.signalpost.org/showthread.php?tid=1086 Wed, 03 Oct 2012 13:10:58 +0000 Shomel122]]> https://irse.signalpost.org/showthread.php?tid=1086
Just wanted to know how this clamplock and HW2000 powered. Voltage current going into power pack for the detaction etc

How you would fault find with high current or low current reading during faults?]]>
Just wanted to know how this clamplock and HW2000 powered. Voltage current going into power pack for the detaction etc

How you would fault find with high current or low current reading during faults?]]> https://irse.signalpost.org/showthread.php?tid=741 Tue, 08 Feb 2011 00:27:10 +0000 Saraswathi]]> https://irse.signalpost.org/showthread.php?tid=741
Q1) Can anyone explain the types of point machines used on the main line and underground of UK, when & why?

Q2) Occassions where we use trailable, non-trailable and High thrust point machines?

Q3) What is the difference between Facing Point Lock (FPL) and Ground Lock (GL) and when do we adopt them?]]>
Q1) Can anyone explain the types of point machines used on the main line and underground of UK, when & why?

Q2) Occassions where we use trailable, non-trailable and High thrust point machines?

Q3) What is the difference between Facing Point Lock (FPL) and Ground Lock (GL) and when do we adopt them?]]> https://irse.signalpost.org/showthread.php?tid=603 Thu, 22 Jul 2010 17:12:36 +0000 PJW]]> https://irse.signalpost.org/showthread.php?tid=603 Quote:Hi,
I want to attempt the fault tree for Points. I request you to guide me to do that as the way you helped for DC Track Circuits in the below thread:

http://www.irseexam.co.uk/showthread.php?tid=294.

Please help.
First think about what "points failure" means. You ought to be able to list a number of different "top events"- diverse ways in which a set of points might adversely affect the efficient and safe operation of the railway. Some may cause delay or prevent the passage of traffic altogether, others may be immediately and directly dangerous, others perhaps a latent fault which lies dormant for a while before having its adverse effect. In doing this you are looking "top down" by regarding "points" as components within the entire railway system.

Then think about all the things that could go wrong and compile yourself a list of faults.
a) Think about the whole range of component parts: mechanical, electrical, signalling, P'Way, power, within the mechanism itself and all its related support equipment and interconnections.
b) Also think about the manner in which they go wrong: normal physical wear, deterioration due to age, chemical attack, abnormal loading, mechanical shock, vibration, electrical overload, extremes of weather, user abuse, vandalism .......
In doing this you are looking "bottom up" by regarding "points" as a system composed of smaller components.

So try to pair things up in typical combinations that displays your knowledge of point mechanisms and of failure modes:
part a may seize up (why?)
part b may loosen (why?)
part c may leak (why?)
part d may become detached (why?)
part e may burn out (why?)
part f may fracture (why?)
part g may become out of alignment (why?)
..................................................
something external x may obstruct (why?)
something external y may cause physical damage (why?)
someone z may do something careless (why?)

Now what you now need to do is to consider what faults in what combination and in what circumstances conspire to create the various top level events which you identified initially.

Connect up in a logical manner using AND / OR gates to combine the various threads suitable, then job done.
Simples.

So have a go and submit your efforts.
Use the example for a signal in the GM Rail event thread as an example from which to work.]]> Quote:Hi,
I want to attempt the fault tree for Points. I request you to guide me to do that as the way you helped for DC Track Circuits in the below thread:

http://www.irseexam.co.uk/showthread.php?tid=294.

Please help.
First think about what "points failure" means. You ought to be able to list a number of different "top events"- diverse ways in which a set of points might adversely affect the efficient and safe operation of the railway. Some may cause delay or prevent the passage of traffic altogether, others may be immediately and directly dangerous, others perhaps a latent fault which lies dormant for a while before having its adverse effect. In doing this you are looking "top down" by regarding "points" as components within the entire railway system.

Then think about all the things that could go wrong and compile yourself a list of faults.
a) Think about the whole range of component parts: mechanical, electrical, signalling, P'Way, power, within the mechanism itself and all its related support equipment and interconnections.
b) Also think about the manner in which they go wrong: normal physical wear, deterioration due to age, chemical attack, abnormal loading, mechanical shock, vibration, electrical overload, extremes of weather, user abuse, vandalism .......
In doing this you are looking "bottom up" by regarding "points" as a system composed of smaller components.

So try to pair things up in typical combinations that displays your knowledge of point mechanisms and of failure modes:
part a may seize up (why?)
part b may loosen (why?)
part c may leak (why?)
part d may become detached (why?)
part e may burn out (why?)
part f may fracture (why?)
part g may become out of alignment (why?)
..................................................
something external x may obstruct (why?)
something external y may cause physical damage (why?)
someone z may do something careless (why?)

Now what you now need to do is to consider what faults in what combination and in what circumstances conspire to create the various top level events which you identified initially.

Connect up in a logical manner using AND / OR gates to combine the various threads suitable, then job done.
Simples.

So have a go and submit your efforts.
Use the example for a signal in the GM Rail event thread as an example from which to work.]]> https://irse.signalpost.org/showthread.php?tid=474 Wed, 14 Jul 2010 15:43:03 +0000 Hort]]> https://irse.signalpost.org/showthread.php?tid=474
I have attempted some questions from the 2008 paper. Any comments would be welcome.]]>
I have attempted some questions from the 2008 paper. Any comments would be welcome.]]> https://irse.signalpost.org/showthread.php?tid=449 Thu, 17 Jun 2010 19:20:34 +0000 PJW]]> https://irse.signalpost.org/showthread.php?tid=449
I have found what I think is a good question to start off with, because it is neither extremely brief nor too wordy and covers a topic sufficiently universal that all should be able to tackle to at least a certain degree.

You are therefore invited to have a go and post your attempts here (or using the answers anonymous facility if you prefer) by 28/06/10


1994 Question 2

Identify the features of

a) power operated points and

b) lineside signals

that affect both safe operation and reliable operation of a railway. Describe the measures that you would take to ensure that they remain safe and reliable in operation.

I suggest you look at this thread and its attachments prior

You may also find that these examples give some ideas re presentational techniques]]>
I have found what I think is a good question to start off with, because it is neither extremely brief nor too wordy and covers a topic sufficiently universal that all should be able to tackle to at least a certain degree.

You are therefore invited to have a go and post your attempts here (or using the answers anonymous facility if you prefer) by 28/06/10


1994 Question 2

Identify the features of

a) power operated points and

b) lineside signals

that affect both safe operation and reliable operation of a railway. Describe the measures that you would take to ensure that they remain safe and reliable in operation.

I suggest you look at this thread and its attachments prior

You may also find that these examples give some ideas re presentational techniques]]>