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Hellier and Gasson Control/Apparatus

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Hellier and Gasson Control/Apparatus

Unread postby Mad Mac » Mon Apr 9, 2018 5:09 pm

Reference to the above is made in the report into a collision at Dumfries in 1944. 300+ years of Signal Engineering experience in an e-mail discussion has yielded no knowledge or recollection of this, which appears to be associated with slotting of multiple distants on the same posts as homes - indeed, British Patent 16662 was issued in 1911. Anyone here heard of it?

http://www.railwaysarchive.co.uk/docsum ... docID=1386

(Link added for those who may wish to know more about the device and the accident - SJ)
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Re: Hellier and Gasson Control/Apparatus

Unread postby Mike Hodgson » Mon Apr 9, 2018 8:37 pm

Intriguing. I've never heard of these before either.

That is not quite how I read the report however. Would be a lot easier to understand with diagrams, but I suppose wartime shortages precluded that. At first I thought they meant there were three splitting distants all off - which of course one might expect a driver to challenge! But the other distants that were off were Nos 3 and 4 box distants. Those boxes were authorised to lower their distants if they noticed that 1 and 2 distant (controlled by thee device which failed) was off. In other words those distants were apparenly not slotted nor indicator worked. It is also unususal in that the same distant arm seems to have applied to both the Main and Lockerbie routes.

The obsolescent device seems to have worked by having the counterweight sliding back and forth along a crank, and this seems to have slotted the arm which acted as distant for both nnd 2 boxes to their respective levers, at least until the counterweight falling off caused a slotting failure which failed tlo return the distant arm to caution.
No 3 box home signal was on the same post as this distant. and one would normally expect slotting between home and distant on the same post, but the the wording of the report seems to suggest that the distant controls device was interlocked with this home signal rather than slotted with it, although I'm not convinced that this isn't just poor wording.
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Re: Hellier and Gasson Control/Apparatus

Unread postby Mad Mac » Mon Apr 9, 2018 10:39 pm

One of those on the e-mail discussion has turned up the actual patent. Anyone interested - PM me your e-mail address.
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Re: Hellier and Gasson Control/Apparatus

Unread postby Andrew Waugh » Tue Apr 10, 2018 12:01 pm

The patent can also be inspected/downloaded from https://worldwide.espacenet.com/publica ... cale=en_EP

The counterweight is not shown on the patent diagram, although it is referred to in the textual description (it connects to, and operates, Crank P). The counterweight is not intended to slide along the arm; it's just an ordinary an ordinary lever plate as applied to any signal to pull the signal wire back when the lever is restored. In this case it also disconnects the slot.

The operation of the slot is quite simple. It's installed in Box B under the distant lever. There is a vertical slide operated by Box B distant lever. There is a vertical hook which is connected to the distant signal wire. There is a horizontal slide which moves the hook to engage/disengage with a pin on the vertical slide. If the hook is engaged, reversing Box B distant lever lifts the hook and clears the distant.

The horizontal slide is connected to Box A distant lever. It moved to engage the hook when Box A distant lever was reversed. The counterweight (that failed) restores the slide, disengaging the hook, when Box A distant lever is restored. The failure was that the counterweight fell off, preventing the horizontal slide from restoring, and leaving the hook permanently engaged.

The whole devise is more complex than a conventional slot, and it is not clear to me its benefit. The main difference was that it enforce a sequence. Box A has to pull their distant lever first, then Box B can clear their distant lever.
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