Trainstop Failures

Well not so good. You are confusing two different types of train stop failure here. The first type (obstruction under trainstop or loss of air) causes a dual aspect while the other sort (Trainstop failed down or trainstop head broken off ) causes the signal and signals a braking distance to the rear to remain at danger.


Well I would expect all signals in rear of the signal concerned to remain at danger out to the braking distance. In practice this is often achieved by causing the track circuit immediatly in advance of the signal to fail, and this being in the overlap causes the signals in rear to remain at danger as well.
To take an example, if the trainstop on signal OP29 at Edgware Road were to fail down after a train departs eastbound then this would cause BP track to fail down (and also BQ) and since BP track is required clear for OP290, the draw up, to clear then this also fails. (As it happens this failure would also cause BQ track to fail down but this is just a quirk of Edgware Road being such a tight and compact site)

Ok, how would the signalling know the trainstop head is broken off? I can understand there being a check mechanism to make sure it's up when it's meant to be and down when it's meant to be...

to pick up the track relay of the replacing track you need to feeds one comes from the track itself know has the R side and energises one coil the other comes from trainstop via 1's contact which is know as the Q side which energises the other coil thus picking the relay up (energising it) now that track relay a contact of that is in the selection for the signal behind also if home signals are involved maybe the one behind that aswell so if the head was in the fully ON postion 1's contact would not make so the TR (track relay) would never pick up thus keeping the signal behind and atleast one good trainstop in full working order

Surely in and of itself the breaking of all the contacts in the trainstop cannot put the replacing track down if the latter happens to be up at the time the defect occurs. Rather, once the track is down for other reasons (ie passage of a train) it subsequently remains down when those reasons no longer apply. This is implied by the phrasing of the second part of your post which talks about signals being maintained at danger, but nothing about them being put to danger, as would occurr with a 'spontaneous' track failure.

Questions dear sirs. How much does a trainstop weigh (I would estimate 30-40 kgs) and are spares held anywhere for emergencies? There is a nice shiny one at Barbican on the eastbound platform. It looks either new or overhauled or do you paint them? Also are there are oil filled trainstops? Someone I was working with insisted there were some around the system and were fed by a tank off track though I've never seen one before.

Ta. If we worked on the premise that 25kg is the maximum for manual handling regulations then I'd guess 70kgs for comfort. I have a set of trainstop diagrams somewhere...

As someone who changed many a trainstop, sometimes as many as three in a shift, let me add a comment or two.

aetearlscourt has said most of what I would say. He mentions the various standard trainstops in use today as the HO,HT,J & K. As he says the latter two are self oiling, this means that the oil is mechanically pumped around inside the trainstop from a sump within it as an auxilliary action of the normal operation of the trainstop.
All trainstops are regularly maintained whether they are 'self oilers' or not as they all have oiling points, there is also the matter of vibration and rail wear, rerailing etc which will or may put a trainstop out of gauge in more ways than most would consider at first glance. So they are gauged and the lid has to come off to check the correct operation of the contacts and the security of the electrical connections.

There are other trainstops, the central line used to have modified K types called KCs but the trainstop was the same with a bracket fixing instead of two of the four feet to fit the reduced size tunnels. On the Picc there are modified J types between Hatton Cross and Heathrow, yes an outside type used in cut and cover tunnel with two feet cut off to accommodate fixing next to F/B rail. I believe the JLE has some modified types too from what I used to see in the stores but having never worked on it I can't say any more than that.

Again as aetearlscourt suggests the only lineside oiltanks were contained below track level beneath the point heater consoles which were basically pump cabinets pumping hot sticky and smelly oil through the special rail chairs linked with hoses and jubilee clips. The oil itself smelled rather fishy and stuck like napalm to the skin, very nasty stuff indeed especially when having to work on the submerged pump in the oil sump.

As for handling trainstops I can't recall the weight but in fact even when four people are carrying one it still breaches all the handling guidelines because a trainstop is an irregular shape and has an irregular weight distribution such that with the HT and K types most of the weight is at the head end, especially since the replacement of the old Midland motor with the new and lighter aluminium type, and in the HO and J types it is on the side where the head is and biassed towards one end. The trainstop is officially carried on four hooks but finding four identical hooks can be a challenge. Also to do the job properly would require four identical individuals in terms of relative height and arm length. Invariably when four people carry a trainstop most of the weight is taken by two or sometimes one individual! There is nothing comfortable about lugging a trainstop but it goes with the job as most of the kit is similarly difficult to transport though in many ways it is far easier today than when I began on Signals in 1977.

As for the contact netralising spring, one would normally expect the track to be down when the head is knocked off unless someone has swung a sledgehammer at it, so it can't pick up when the track is unoccupied following the passage of a train. If by failure all the contacts have broken while the track is up then it will remain up until the passage of the next train when the track will fail down. The point is that regardless it fails safe.

The JLE uses HO types, but with a litton connector rather than the flipper.

Are the modified J types between Hatton X and Heathrow the ones referred to in the Emergency Stores book as a 'Heathrow' trainstop?

tom when i was finishing my apprenticeship in 1998 we were putting trainstops down around SMD on the JLE but taking out the litton plugs and replacing them with the standard snake these trainstops came brand new from westinghouse

Yep I would imagine so, I don't know why they didn't give them a designation of their own but I suppose as there are only a few of them it wasn't warranted. On the maintenance modules they just used to show up as 'J-modified'.

Now you mention it I do recall the trainstops with litton connectors although I never looked too closely at them. I also recall the EP valves mounted on white plates for the JLE too.

well it took them till around 1997-1998 to start using cembres (petrol drilling machines) instead of the fun hand bikes (manual chain driven drill) which are still used if the machine packs up

o yes remember them well doing stretcher bars