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Point Machines used in UK
#1
Hi,

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?
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#2
(08-02-2011, 01:27 AM)Saraswathi Wrote: Hi,

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?

As an initial response to part of the question, the two most common point machines used in the UK over the last 40+ years are
1. the Alstom (previously GEC- General Signal) HW2000 series, and
2. the Invensys (previously Westinghouse) style 63.
Both have "Facing Point Locks" internal to the machine and therefore called "combined machines" [the very earliest machines worked more similarly to mechanical points with one drive to move the rails and another drive to operate the FPL in the 4ft (i.e between the rails) thus bolting the lock strtcher into place].

The other point Operating Equipment [POE] that we use include:
a) clamplocks (now re-engineered as the In Bearer Clamp Lock), and
b) The High Performance Switch System
These are the only types that have the high thrust needed for long switches of heavy rail section and are the types to be used for most major relaying work nowadays.

There are also a range of other mechanisms, both ancient and modern, but for pure "point machines" the HW is dominant, the 63 having fallen a bit out of favour, but still used in quantity.

I think I have some manufacturer's info on each that I'll upload later if I can.
For now though I have put the wiring diagram for an HW; it is a 4 wire machine with separate pairs of cores used to rotate the motor in each direction. You will note the contacts that operate to cut off the motor from the supply near the end of its motion and also the electromagnetic clutch- the motor free wheels gradually to a stop after its feed is disconnected, whereas the machine itself has already stopped moving. Note the cotact next to the motor which is disconnected as soon as the manual operation handle is being inserted and remains broken until the handle is fully withdrawn and a reset plunger operated to switch the machine back to power operation again.
In the middle of the page are the detection contacts- a 4 wire circuit is double cut through either the Normal or Reverse contacts as applicable.

Clamplocks were introduced in late 1970s I think. British Rail felt point machines too expensive and developed the clamplock, much of which could be made in railway engineering workshops, but with manufacture of hydraulic power packs by specialist suppliers. Although perfectly ok in many applications and indeed better than point machines in some specific cases (notably when track not precisely to gauge), they can't cope very well with track twist and contaminants like coal dust. Reliability can be variable; if the rails are drilled accurately, correctly installed and maintained they are fine but if rails not quite correct then will probably always be a bit iffy. Also in heavily used applications they don't last as long as machines before needing renewal. They do have some advantages besides their price; for example easier to transport to site, don't need extended P'Way bearers etc and for a long time were the only means of driving long high speed switches, good for switch diamonds etc. However in many applications the saving in CAP-EX is offset by higher OP-EX, particularly as the cost of "track access" for maintenance is viewed somewhat differently in today's railway.
Therefore the tendency was only to use them on the less intensely used railway and in the specific situations when they had ther advantages.

After a time in the shadows have now made a comeback, reborn as the IBCL, helped a bit by the HPSS not yet having proved itself as good as had been initially hoped. One has to live with equipment for 10+ years sometimes to see the various problems gradually manifest themselves......so it is a bit like a pendulum and it may swing back in 5 years time!


Perhaps someone from the Underground can explain their various air driven mechanisms and their modified clamplock; indeed the Invensys Surelock (which is an upgrade from the style 63 but not used on Network Rail at all at present)




Attached Files
.pdf   HW point machine internal wiring.pdf (Size: 128.1 KB / Downloads: 498)
PJW
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#3
(08-02-2011, 01:27 AM)Saraswathi Wrote: Hi,

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?

The "WHY" in Q1 is explained on the mainline in Network Rail's document NR/SP/SIG/19809 "Point Operating Equipment" which sets out their policy for selection of different types of machine. This information might not be a lot of use to you if you do not have access to NR standards and I am unable to post it as NR not not make their standards publically available. Although I have access to it via my company's login to the technical index website, one of the terms of use is that I do not make standards available to others.
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#4
I finally been able to split the pdf supplied by Adikarina relating to the Surelock into manageable parts that can be placed here; I have eliminated the non-useful pages.

Its fundamental design is based on that of the 63; however to think of it just as a modernised version is to do it a diservice. It is modular allowing significant components to be replaced quickly on site, the detection arrangements are thoroughly redesigned and it incorporates an entirely novel backdrive arrangement with combined backdrive crank / supplementary detection units. It has also reverted to the means of handcranking used on the earlier M3 series, with the great advantage of keeping flesh on the fingers of the hand which cranks!


Attached Files
.pdf   Surelock sect1.pdf (Size: 439.09 KB / Downloads: 392)
.pdf   Surelock sect2.pdf (Size: 1.05 MB / Downloads: 293)
.pdf   Surelock sect3.pdf (Size: 1.34 MB / Downloads: 261)
.pdf   Surelock sect4.pdf (Size: 1.66 MB / Downloads: 251)
PJW
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#5
Here is the information relating to the old HA and HB machines which is useful to see the evolution of point machines from a motor driving mechanical points to something a little more modern.
The HB manual seems to date from my date of birth; there are still some machines in service, including a few at Reading soon to be eliminated by the remodelling. The HB is clearly the ancestor of the HW machine which is still being installed for new works, albeit that it is no longer preferred for many applications.


Attached Files
.pdf   HA machine sect1.pdf (Size: 1 MB / Downloads: 265)
.pdf   HA machine sect2.pdf (Size: 1.13 MB / Downloads: 165)
.pdf   HB machine sect1.pdf (Size: 893.04 KB / Downloads: 188)
.pdf   HB machine sect2.pdf (Size: 1.42 MB / Downloads: 162)
PJW
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#6
Here is the HW information; now made by Alstom, previously GASL, previously GEC-General Signal, grew out of AEI, GRS, SGE etc; the point machine has outlived very many of the companies which manufactured it over the years.....

I hadn't forgotten- just distracted by change of job and other events!


Attached Files
.pdf   HW machine sect1.pdf (Size: 599.51 KB / Downloads: 557)
.pdf   HW machine sect2.pdf (Size: 1.52 MB / Downloads: 356)
PJW
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#7
This is the Westinghouse, then Invensys point machine which was the broadly contemporaeous competitor with the HW machine and has now evolved into Surelock as discussed earlier.


Attached Files
.pdf   63 machine sect1.pdf (Size: 1.09 MB / Downloads: 337)
.pdf   63 machine sect2.pdf (Size: 1.52 MB / Downloads: 210)
.pdf   63 machine sect3.pdf (Size: 526.21 KB / Downloads: 190)
PJW
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#8
Some info re London Underground, particularly relating to the Ground Lock and how it is added to the standard Network Rail clamplock, but also including other info re the setting and locking of points from an LU perspective.




(08-02-2011, 01:27 AM)Saraswathi Wrote: Hi,

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?


Attached Files
.doc   LU Points.doc (Size: 779 KB / Downloads: 298)
.pdf   LU Points.pdf (Size: 676.32 KB / Downloads: 41)
PJW
Reply
#9
Thanks Peter....This notes is really useful & making more sense.

Regards,
Saraswathi
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#10
Google Images has many links for photos of FPLs shown here.

Not sure what a ground lock is. I wonder if it aligns to a ground frame? PJW?

Jerry
Le coureur
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