Burning question of no consequence

Terrontress

Something I have always wondered:

Beneath platforms where DART services the station, there is a little slider with several settings.

What does that do and is it ever changed?

mk6705

Terrontress wrote: »

Something I have always wondered:

Beneath platforms where DART services the station, there is a little slider with several settings.

What does that do and is it ever changed?

Your question is vague, but it may be axle counters.

LLU

It seems to be some sort of reference point for measuring the camber, curvature, position, etc of the track. If you look closely you'll see words like 'CANT' and 'radius of curve' inscribed on them.

Terrontress

LLU wrote: »

It seems to be some sort of reference point for measuring the camber, curvature, position, etc of the track. If you look closely you'll see words like 'CANT' and 'radius of curve' inscribed on them.

But what is interesting is that they only seem to occur on electrified stretches. You'd think that such measurements are equally important on diesel only sections.

It does make sense that if the slider part, which looks like a mixing desk's slider were to stay still and the platform sunk then it could be easily detected but then would those be the best markings rather than just a distance measurement.

Thanks for all the ideas so far!

steamengine

Are they at every Dart station ? I noticed one in Lansdowne Road or thereabouts. Wouldn't mind finding the exact answer myself ?

corktina

is it that they were installed when the Dart was rebuilt and will be installed at any other stsation re-built? Are they on the WRC for instance?

Hilly Bill

LLU wrote: »

It seems to be some sort of reference point for measuring the camber, curvature, position, etc of the track. If you look closely you'll see words like 'CANT' and 'radius of curve' inscribed on them.

Close enough . Its to measure the clearance either from the platform or the overheads it would say on it what its for.

Terrontress

Hilly Bill wrote: »

LLU wrote: »

It seems to be some sort of reference point for measuring the camber, curvature, position, etc of the track. If you look closely you'll see words like 'CANT' and 'radius of curve' inscribed on them.

Close enough . Its to measure the clearance either from the platform or the overheads it would say on it what its for.

To measure the clearance from the platform or the overheads to what?

And why would they not use numerical measurements?

I think I may not have explained myself fantastically but I can't think of any other way.

It's not just at platforms. There are quite a few between Pearse and GCD.

Terrontress

corktina wrote: »

is it that they were installed when the Dart was rebuilt and will be installed at any other stsation re-built? Are they on the WRC for instance?

I've never been to the WRC so couldn't say.

Hilly Bill

Terrontress wrote: »

To measure the clearance from the platform or the overheads to what?

And why would they not use numerical measurements?

I think I may not have explained myself fantastically but I can't think of any other way.

It's not just at platforms. There are quite a few between Pearse and GCD.

To the track. Its a gauge so they know when packing what the distance from the overheads should be.

Terrontress

Sorry to harp on about it but this is a picture of what I mean, in case there was a lack of clarity. It isn't in Ireland but it is the same idea.



Is that a measurement of the track from the unit?

Hilly Bill

Its a gauge, the block is level with the rail. Its to measure the Cant etc. It will say on it what its for.

merengueca

It's a Datum Plate. The position of the track relative to the plate is recorded. If the position is altered by tamping/lifting etc then the plate should be altered to reflect the new position.

You will probably be see the Cant and RE (Running Edge to block) measurements along with the Datum Plate reference number.

patrickbrophy18

I used to think that these were speed restriction units that slowed the DART down while it was entering the station.

L1011

patrickbrophy18 wrote: »

I used to think that these were speed restriction units that slowed the DART down while it was entering the station.

Thats done (well, enforced) using ATP via the track circuits.