Inner Rails

[Chip1035]

I've always been wondering what the rails in-between the rails the train rides on, are for (see pics). I haven't been on the front car of any other line other than the , to notice if these rails are on other lines. I noticed rails that just sit in-between the rails without being nailed down which I believe is spare rails but not these rails. Are they used by service cars?

 

At Hunters Point and goes on to Main St.

 

This inner rail I believe is to help prevent the train from tilting? I only notice these kinds on bends and turns.

[Bill from Maspeth]

I've always been wondering what the rails in-between the rails the train rides on, are for (see pics). I haven't been on the front car of any other line other than the 7, to notice if these rails are on other lines. I noticed rails that just sit in-between the rails without being nailed down which I believe is spare rails but not these rails. Are they used by service cars?

 

At Hunters Point and goes on to Main St.

 

This inner rail I believe is to help prevent the train from tilting? I only notice these kinds on bends and turns.

Photo's 1 & 2: In case the train derails, the train won't go flying off the structure.

 

Photo 3: the platform will keep the car in place, but the rail in between is called a guard rail. Around sharper curves, the flange of the wheel is in between those 2 rails to prevent it from derailing.

[Chip1035]

That makes sense as to why I only see it when the when it's above ground on the elevated tracks and not underground. Thanks... Always wondered about this since a kid and I looked out at the tracks in the 1st car.

[INDman]

Photo 3 is actually a guard rail and they are used on the inside rail of any curve.

[LRG]

That makes sense as to why I only see it when the when it's above ground on the elevated tracks and not underground. Thanks... Always wondered about this since a kid and I looked out at the tracks in the 1st car.

 

They are located underground as well, it just may be too dark for you to see.

[Y2Julio]

That makes sense as to why I only see it when the when it's above ground on the elevated tracks and not underground. Thanks... Always wondered about this since a kid and I looked out at the tracks in the 1st car.

 

They're on all elevated tracks.

[Bill from Maspeth]

Photo 3 is actually a guard rail and they are used on the inside rail of any curve.

..............which is what I mentioned in paragraph 2. Post #2 of the thread.

[SubwayGuy]

The other advantage of a guard rail is that since the wheel tread doesn't go over it, you can slobber the hell out of it with track grease so that when the flange rubs against it, it doesn't wear away the steel. Guard rails wear away slower than running rails (which can't be greased as heavily) would if they were used for that purpose. And as previously mentioned this arrangement also prevents derailments.

 

I believe photos 1 and 2 that rail is known as a Guide rail, but its purpose is as others have stated...it keeps a derailed car from falling off of the structuer.

[Joe]

I know a few people who like to grease the whole head of the running rail...

[SubwayGuy]

I know a few people who like to grease the whole head of the running rail...

 

Yup. We're thinking of the same people. Heh...Nothing like a subway car trying to spin donuts on track early in the morning. "I love the smell of grinding steel early in the morning" -GP

[Joe]

Hey, you save power if you can just sliiiiiide through the yard!

[SubwayGuy]

Hey, you save power if you can just sliiiiiide through the yard!

 

True...perhaps the BRT should have had sliding clocks too then. However it's a safe bet that the shop superintendent comes after you when your wheels look like the crescent moon!

[BroadwayBuffer]

Hey, you save power if you can just sliiiiiide through the yard!

 

As if some operators don't go fast enough through the yard. :cool:

[TwoTimer]

And when guard rail are in switches they're called stock rail.

[TRO man]

Hey Chip,

The "inner rails" that you refer to in your pictures are not guard rails.Guard rails are located at curves and are set about 2'' from the running rail to keep the wheels in place. The rail in your picture is called the EPR rail (emergency protection rail) and is used on elevated structure in case of a derailment ,in the field it's known as the" black rail" because of it's color (grease drippings and all). Hope that clarified things for you.

[metsfan]

They are called check rails in switches, and guide rails everywhere else. Guide rails allow a derailed train, or a train going around a tight curve, to keep the wheels from climbing outside the gauge entirely, possibly leading to catastrophic damage to vehicle or infrastructure. There is a possibility in some situations of a truck jamming to one side around a tight curve if these guide rails are not in place.

 

Check rails make sure the wheels stay on the right path through a switch. Check rails are far more common (pretty much every switch has one) than one sided guide rails, which are typically limited to higher speed passenger operations

 

All most all elevated structures including most trestles and every lift bridge i have seen have the guide rails to keep a derailed train from leaving the gauge completely in the event of derailment and from falling off or damaging the bridge.

 

- A

[CenSin]

They are located underground as well, it just may be too dark for you to see.

Underground tracks have less of them. I'm sure he's not blind to that fact. :cool:

[WannaBeMTA12]

Photo 3: the platform will keep the car in place, but the rail in between is called a guard rail. Around sharper curves, the flange of the wheel is in between those 2 rails to prevent it from derailing.

 

so thats why that screeching sound is so unbearable on turns...that guard rail

[CenSin]

so thats why that screeching sound is so unbearable on turns...that guard rail

The screeching happens with or without the guard rail, though it does become unbearable with the guard rail adding extra friction to the wheels.

[SubwayGuy]

The screeching happens with or without the guard rail, though it does become unbearable with the guard rail adding extra friction to the wheels.

 

The guard rail doesn't add "extra" friction to the wheels. It takes the friction that would otherwise be borne by the running rails. Less friction on the running rails means they don't have to be replaced as often. Also the layers upon layers of track grease slobbered on the guard rails reduce the friction somewhat so that the guard rail lasts longer.

[CenSin]

The guard rail doesn't add "extra" friction to the wheels. It takes the friction that would otherwise be borne by the running rails. Less friction on the running rails means they don't have to be replaced as often. Also the layers upon layers of track grease slobbered on the guard rails reduce the friction somewhat so that the guard rail lasts longer.

So you're saying there is less resistance to train movement than when the train is going straight? Between switches with guard rails and switches without them, the ones without them make less noise; I assume the extra noise comes from the additional rubbing against the guard rails. The grease surely reduces the friction, but is there a net reduction in friction compared to when the train is simply running on straight rail?

[Joe]

The guard rail acts as a block to prevent the wheels from walking out of the gauge on a curve. On a guarded curve, the non-tread side of the flange rubs against it, creating friction.

 

Modern rail wheels are not perfectly cylindrical, they're actually conical. On tangent track, neither flange should be riding against the rail and the wheelset is self-centering in the gauge.

[SubwayGuy]

So you're saying there is less resistance to train movement than when the train is going straight? Between switches with guard rails and switches without them, the ones without them make less noise; I assume the extra noise comes from the additional rubbing against the guard rails. The grease surely reduces the friction, but is there a net reduction in friction compared to when the train is simply running on straight rail?

 

As Joe said, the wheels are tapered. They are highest closest to the flange and lowest closest to the side of the subway car. To add to what Joe said, this is why you won't see guard rails on very slight and gentle curves. In that case, the taper of the wheel is sufficient to keep the train on a path that allows it to negotiate the curve without a flange hitting anything.

 

And on tangent (straight) track, like Joe said each wheelset is self centering. The friction when travelling on straight or slightly curved track is very minimal. Ideally it is only so much as borne by the tread of the wheel when gripping the rail to propel the train.