Point Machines used in UK

[PJW]

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

I had hoped that the attachment in yesterday's post had made that clear! It isn't a form of point equipment; rather it is a component that is used in conjunction with / part of a mechanism to give an additional mitigation to certain risks.

[Jerry1237]

Hmm, missed that (Ref: LU Points.doc). Does anyone have a photo?

[PJW]

Hmm, missed that (Ref: LU Points.doc). Does anyone have a photo?

I'll try to get some more, but the doc does have included within it a pair of photographs of the groundlock (WL) mounted as part of the modified (to use air rather than hydraulic fluid) clamplock

[Saraswathi]

Hi Jerry & Peter,

I have attached my collection of ground lock pictures on different types of point machines used in LUL.

Regards,
Saraswathi Penneru

[PJW]

That's good; don't know where you got those from, but better than any one thing I have yet found- and I work for the company. I do have some Surelock photos which I took at Whitechapel, so I'll add them tonight if I remember

Hi Jerry & Peter,

I have attached my collection of ground lock pictures on different types of point machines used in LUL.

Regards,
Saraswathi Penneru

[Darryl Baker]

Does anyone have any information on the clamp lock? Similar to that of the Surelock and HW pdf's attached? I am trying to do a points machine comparison.

Cheers

D

[PJW]

I have pdf'd a Powerpoint presentation that may be useful for the pictures, but there is little explanation I am afraid

Does anyone have any information on the clamp lock? Similar to that of the Surelock and HW pdf's attached? I am trying to do a points machine comparison.

Cheers

D

[PJW]

In connection with the London Study Group, I have produced a large (both in number of pages and particularly in file size) Powerpoint presentation. It isn't yet finished yet and cit ertainly has some rough edges at the moment, however for what it's worth I have now made it available to download from http://db.tt/ucDqnf0c

For some of the slides there is some additional text, so it is worth looking at it in Notes View. Otherwise it can be run as a presentation (not that there is much animation), but beware that one of the things which is certainly unfinished at present is the division into custom sub-presentations appropriately hyperlinked so it is a bit of a monster to find way around.

As and when I have the opportunity to resolve this, I'll upload a new version that should utilise the same link above. For now though there is quite a bit of extra information compared with the pdf earlier within this thread.

It is worth noting that for the last decade there hads been at least one, often two, questions specifically on points within the module 5 qestion paper.

I have pdf'd a Powerpoint presentation that may be useful for the pictures, but there is little explanation I am afraid

Does anyone have any information on the clamp lock? Similar to that of the Surelock and HW pdf's attached? I am trying to do a points machine comparison.

Cheers

D

[Chall1986]

Hi there, what is the difference between HW1000 to the HW2000?

I am also after the circuit diagram for the HW1000 point machine, tried looking on various websites but had no joy

Thank you

[PJW]

I don't have any significant experience of the HW1000 but the main difference is most certainly that it has a "split field" motor (the incoming power is fed not only to the armature but also to the fixed windings to create the magnetic field) whereas the HW2000-2121 uses a permanent magnet to give a constant magnetic field.
Traditionally HW1000 were used on BR Southern Region which (generally) features dc third rail electrification whereas HW 2000s etc used elsewhere (as ever with sweeping generalisations this is too simplistic, but paints an overview which is a pretty accurate approximation).

I am not sure but have always been under the impression that the original rationale was that the HW1000 were immune from false operation from traction current in the scenario of earth faults giving a linkage between the traction supply (being returned to substation via the running rails which are deliberately earthed at various paces and inherently casually earthed throughout their length) and the signalling supply (which is nominally earth free although in reality rarely is completely- connections to point machines being notoriously "earthy").

At some time (and I guess this was mid - late 1980s, obviously there was a re-assessment of the risks of using HW2121 in such environments which presumably determined that the risk was negligible and in addition there was some positive benefit of using in preference to HW1000. As far as I know these were then used in preference, but the existing HW1000s were not eliminated, but possibly overtime are gradually disappearing through piecemeal renewals as well as major resignallings. I am not clear now what the difference was between HW2000 and HW2121; it is possible that the HW2121 has some form of modification which means its use in dc environments is suitable whereas a HW2000 wouldn't be- I seem to recall the change happening around the same time as the policy change.

Certainly the HW1000s could not be utilised on ac electrified railway and the HW2000s were the "ac immune" variety. I suppose it could just be that the HW2000s were always known to be ok everywhere but were more expensive / less efficient. In the past less consideration was given to the benefits of standardisation and initial costs dominated (the railways are often stretched for money and in the nationalisation days annual budgets were very important); hence the selection might have been "why pay for immunised machines, for places where there is no need or that immunisation?"- I don't know when the machine was introduced but I believe a contemporary of the Westinghouse 63 machine (happy 505h birthday!). At that time most of the railway network was operated by steam, the move to diesel and al the Beeching cuts of the network just about to start and there were only a few pockets of suburban electrification, with the electrification of the West Coast Main Line just about to start- hence the need for ac immune machines would not have been that high.


I think there are a range of associated differences between the HW1000 and HW2000; it certainly isn't just a different motor fitted but I m afraid I do not know where there are diagrams (other than I guess in the lids of the machines themselves). Presumably the changes relate to needing to use the same incoming power feed (whether on a 3-wire or 4-wire variant; seem to remember that the default is 4 wire but conversion reasonably straight forward) and arrange things such that the appropriate polarities are fed to the fixed and to the rotating windings such that the correct direction of rotation of the motor results.

The HW1000s certainly have a mechanical clutch (rather than the magnetic clutch of the HW2121s) and have a snubbing arrangement for the motor at the end of its movement- there may be some variation of which I am unaware but some at least have a diode snubbing block that is colour coded red (can't recall what the significance of the various colours actually is, other than it is an important distinction)

I am not at home at present to check, but it may be that the IRSE 1980s text book "Railway Signalling" or indeed some of the earlier "little green books" may have something conceptual (but I guess not the prescriptive detail you may be wanting).

The GEC-General Signal company's HWs have a clear ancestory from earlier SGE machines and of course have themselves been evolving over their long life; I believe that they are nowadays manufactured in Poland. Australia also make their own variant the HW4400 which uses a 120V ac induction motor, includes an internal cut-out timer and has been reengineered to utilise metric rather than imperial sized components. Hence if you do get a drawing from somewhere I caution that it may be that it may not be of completely correct to utilise with any specific machine you may have- certainly won't have auditable version control!

Hi there, what is the difference between HW1000 to the HW2000?

I am also after the circuit diagram for the HW1000 point machine, tried looking on various websites but had no joy

Thank you