Railroad Forums 

Discussion relating to the past and present operations of the NYC Subway, PATH, and Staten Island Railway (SIRT).

Moderator: GirlOnTheTrain

 #1051513  by itzow
 
Does some one know how the MTA NYC has solved the Problem, with the third rail support when the train is crossing a switch?

Especially for double crossover switches, are there some special solutions?
And does some one know how big the distance between the third rail shoes of a car is?
 #1051556  by chuchubob
 
itzow wrote:Does some one know how the MTA NYC has solved the Problem, with the third rail support when the train is crossing a switch?

Especially for double crossover switches, are there some special solutions?
And does some one know how big the distance between the third rail shoes of a car is?
Third rail gaps are not a problem on the subway, since single cars are not run.
 #1051928  by itzow
 
So there are no position in the whole net, where the car lost the power even for a little moment?

Does the cars have buss jumpers between cars in a married pair?

For example in WMATA, if the gap is bigger than 54' they lost the power, thus the lights and the HVAC switches of for a Moment.
 #1051970  by chuchubob
 
itzow wrote:So there are no position in the whole net, where the car lost the power even for a little moment?

Does the cars have buss jumpers between cars in a married pair?

For example in WMATA, if the gap is bigger than 54' they lost the power, thus the lights and the HVAC switches of for a Moment.
On New York Transit Museum charters with Lo-V's and R1-R9's, the lights in each car go out as each car negotiates a crossover. The car doesn't lose propulsion, though.
 #1052028  by mikey cruz
 
Older cars used to "GAP OUT" if they were run in singles or if there were cut outs in a consist that isolated a powered car I believe. Newer equipment has better Bussing to where the only thing I think that happens now is the A/C cuts off for a few seconds. I been outta NY for a few years now so I don't know if the NTT's do that like the R32's & 42's.
 #1052042  by hi55us
 
mikey cruz wrote:Older cars used to "GAP OUT" if they were run in singles or if there were cut outs in a consist that isolated a powered car I believe. Newer equipment has better Bussing to where the only thing I think that happens now is the A/C cuts off for a few seconds. I been outta NY for a few years now so I don't know if the NTT's do that like the R32's & 42's.
Entering and leaving GCT every day (going uptown on the 4/5 line) the lights and the AC usually flickers, I assumed it was because of the sharp curve and gaps in the third rail.
 #1052101  by Fan Railer
 
the NTT cars have batteries that supply the lighting on the car when going through third rail gaps. Propulsion and HVAC still cutout for a short period of time if the entire car lacks a third rail contact, but as soon as one of the shoes makes contact, those two systems switch back on.
 #1061179  by truck6018
 
chuchubob wrote:
itzow wrote:the lights in each car go out as each car negotiates a crossover. The car doesn't lose propulsion, though.
The individual car does lose propulsion. It's not an issue unless the whole consist gaps.
 #1075636  by itzow
 
It only interests me when the HVAC switches off for a moment.
Has someone more information when this happens exactly? I mean is there some schematic behind, for example like in Washington that if the car passes a double crossover switch or smth like this?
Is there a system track schematic available for NY?
 #1076147  by Fan Railer
 
itzow wrote:It only interests me when the HVAC switches off for a moment.
Has someone more information when this happens exactly? I mean is there some schematic behind, for example like in Washington that if the car passes a double crossover switch or smth like this?
Is there a system track schematic available for NY?
Only when the entire car loses connection with the third rail system, which is possible at double crossover switches, which are MAD common in the NYC system. nycsubway.org has track maps for ya.
 #1076240  by lirr42
 
Fan Railer wrote:
itzow wrote:It only interests me when the HVAC switches off for a moment.
Has someone more information when this happens exactly? I mean is there some schematic behind, for example like in Washington that if the car passes a double crossover switch or smth like this?
Is there a system track schematic available for NY?
Only when the entire car loses connection with the third rail system, which is possible at double crossover switches, which are MAD common in the NYC system. nycsubway.org has track maps for ya.
Here is the specific page with the track maps.

Like Mr. Railer said, the HVAC will switch off when all the shoes on a car are off the third rail. Double crossovers are the most common, but you might see trains gap in yards, around large curves, or in particularly crowded interlockings.
 #1076805  by itzow
 
Thanks for the answers, but I need it a bit more exactly. Are there some special typs of crossover switches or does they need a special center track distance?
but you might see trains gap in yards
Can you explain this more in detail?
around large curves
I hear this the first time, is there a special radius necessary?
 #1076898  by Gerry6309
 
itzow wrote:Thanks for the answers, but I need it a bit more exactly. Are there some special typs of crossover switches or does they need a special center track distance?
but you might see trains gap in yards
Can you explain this more in detail?
around large curves
I hear this the first time, is there a special radius necessary?
In general, the third rail on the straight side of a switch crosses to the side of the track opposites the turnout. There is a short gap near the switch points to allow the third rail shoe on a car entering the straight rail to pick up power. On the crossing track a piece of third rail occupies the space between the running rails between the tracks. Since there are four pickups on each car, this insures thatmost of the crossover is powered. Only when all four shoes are out of touch, does the car lose power. Scissors crossovers have less third rail, so gaps are more likely. Double Slip Switches are even worse due to all of the moves possible.

Basically, the only good way to approach third rail is by way of the ramped end. Any other way the shoe comes in contact either tears off the shoe or tears up the third rail.

A more noticeable third rail gap occurs at a section break, the point where two third rails, fed by different isolation switches or substations meet. Here, there is a gap which must exceed the dimension between truck centers on the largest car in use by about two feet. This insures that if a car accidentally enters a section which is shut off, it doesn't energize that section with possibly fatal results.

Finally, on modern cars, the lights are powered from the low voltage (battery) circuit. This is usually fed from the 600 via a motor-generator set or DC-DC Converter. When the 600 is lost, the batteries take over. As they discharge, sensors in the lamps turn some circuits off. Thus for a normal third rail gap or section break, the lights stay on. If you happen to ride the "Train of Many Colors", the R-33MLs have the newer type lights. The older cars, and R-33WFs have the older variety, and they will flash going through gaps.
 #1100992  by Disney Guy
 
truck6018 wrote:
chuchubob wrote:
itzow wrote:the lights in each car go out as each car negotiates a crossover. The car doesn't lose propulsion, though.
The individual car does lose propulsion. It's not an issue unless the whole consist gaps.
It is intentional that traction power is not carried from car to car via cables; this would in effect combine all of the third rail shoes on all of the cars which would in turn bridge two (track electrical) sections which could cause electrical problems.

Furthermore it would not make sense to interconnect all of the cars with traction power for the motors but not connect the lights to the shared power also.

Lights going out in each car as the train goes over a crossover or section break is "traditional" to the point where most movies with scenes in a subway train include the lights winking out.

At switches, extra short lengths of third rail can be positioned on the other side of the track so there are not that many dead spots.
 #1101181  by MBTA3247
 
itzow wrote:
around large curves
I hear this the first time, is there a special radius necessary?
I'd like to know about this myself. This is the first time I've heard of having a break in the third rail on a curve other than an ordinary section break.