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Trap point, catch point, which?

Posted: Wed Oct 02, 2019 1:15 pm
by Bufferstop
Just spent a weekend in the company of gricers of every age and intensity, and there seems to be no agreement on what to call these
Trap _Points.jpg

Are they catch points or trap points? I've always assumed that catch points are at the foot of an incline to either divert to a sand drag, or derail a runaway vehicle, but trap points are there to derail or divert any attempt to run unauthorised onto the main line.
That would make those in the picture trap points, as there's no gradient involved, and they are at the exit from a loop. As no one could agree on which was which I looked it up in the wiki. The definition given was the same as I believed but then in some of the example pictures given the captioning was decidedly ambiguous.
What say you?

Re: Trap point, catch point, which?

Posted: Wed Oct 02, 2019 1:34 pm
by footplat47
Are they not both operated by means of a lever or mechical control system Bufferstop. Both are set open or closed by a lever or motor. They seem to be one of the same to me, the only difererence as far as I can see are diferent designs of diferent Railway company practices. They are mainly to protect any locomotive or wagon ect; from entering another track without autherisation by signal or staff. Often placed in positions where it may by possible for loose wagons ect to run away. I have no idea what Wiki says.
I may be wrong as I very often am........ :)
John

Re: Trap point, catch point, which?

Posted: Wed Oct 02, 2019 3:03 pm
by flying scotsman123
I always thought that one stopped trains from proceeding in the right direction i.e. in the event of a SPAD the mainline still wouldn't be blocked, and the other to prevent movements in the wrong direction i.e. in the event of a split train the rear half rolling backwards. Can't remember which was which though!

Re: Trap point, catch point, which?

Posted: Wed Oct 02, 2019 3:16 pm
by footplat47
Hello Flying,,,Could you say that again I am a bit deaf,,,,,,,,Not many teeth either :P

Re: Trap point, catch point, which?

Posted: Wed Oct 02, 2019 4:53 pm
by Bigmet
flying scotsman123 wrote:I always thought that one stopped trains from proceeding in the right direction i.e. in the event of a SPAD the mainline still wouldn't be blocked...

That's the trap point. Attempting to leave a yard, siding, or a platform road not on the main running line, without being signalled for the road an interlocked facing trap point prevents movement onto the running line, and the train would end up on the stops of a short spur or in a sand drag if the driver didn't brake swiftly.

flying scotsman123 wrote:... the other to prevent movements in the wrong direction i.e. in the event of a split train the rear half rolling backwards...

That's the catch point. On the former GNR lines known as 'jack catches'. There was very famously one just inside Kings Cross suburban hotel curve tunnel which was on a 1 in 39 gradient, to stop a suburban train going wrong way into the tunnel, if the loco failed to start the train off the platform and slipped backwards. (What with collisions in very tight single bore tunnels on a seven chain curve and a steep gradient being 'very inconvenient' and especially so in the evening rush hour.)

Re: Trap point, catch point, which?

Posted: Wed Oct 02, 2019 9:02 pm
by Bufferstop
That's exactly as I thought Bigmet, but the discussion was still going around in circles when I ducked out and escaped back to my seat in first class dining, and some of those arguing either way were ex BR. At six quid a go for what is only going to be a non functioning item I'll keep making my own. A slitting disc, a short piece of rail, and some araldite (or solder). I form the diverging stock rail by cutting the rail and the sleepers so that they can be pushed out of line and still have sleepers and chairs on the outside, then put in a piece of filed down rail to make the blade. If you cut the sleepers in the right place, the open blade will sit above the cut and hide whatever you do to the gap in the sleepers. I put a blob of plastic padding into each sleeper then form it to the shape of the sleeper. Where the blade makes contact with the stock rail it's either a spot of solder or a dab of araldite depending on whether or not you want to energise the blade only when the points are set.

[ Edit] Restored Bigmet's name after Google's AI spellchecker changed him to Nutmeg!

Re: Trap point, catch point, which?

Posted: Thu Oct 03, 2019 7:07 am
by stuartp
Trap points stop unauthorised right direction movements, catch points stop unauthorised wrong direction movements. That was the BR operating definition, as far as the engineers were concerned they were all trap points.

Re: Trap point, catch point, which?

Posted: Thu Oct 03, 2019 9:31 am
by Bigmet
Bufferstop wrote:... Restored Bigmet's name after Google's AI spellchecker changed him to Nutmeg!

Now I am feeling a temptation for rice pudding this evening.

Re: Trap point, catch point, which?

Posted: Thu Oct 03, 2019 6:05 pm
by b308
stuartp wrote:Trap points stop unauthorised right direction movements, catch points stop unauthorised wrong direction movements. That was the BR operating definition, as far as the engineers were concerned they were all trap points.


That does sound logical. You trap something trying to go somewhere it shouldn't and catch something that's running away!