third rail question

Nasadowsk wrote: Oh yeah, wheeeee tells you at least one inverter's on. Could be only one, or could be all 4, or some popular combo.

2 propulsion inverters per car. Each one powers both motors on a truck.

Ugh. So, pop an inverter, bye bye truck. Yuck

What did they chop the HP on the M-7's down to, anyway? I'm going to take a WAG here and guess in the area of 700hp...

(Oh yeah, there's probbably a computer parameter to pump that back up. Actually, it'd be kinda neat if they could just bhave the computer set the HP based on train length, i.e., a 6 car train would be higher power than a 12 car one....)

I only know of HP by printed specs. They don't feel the need to tell the rank and file if/when they make changes like that.

With the communication network, what you want could probably be done.
There is reference in one of the books to the computers in the train communicating to each other to limit the third rail current draw in the entire consist to (I believe) somewhere in the range of 10,000 - 12,000 amps. (I'll put it on my list of things to find.)
That could mean that a 12 car train may in fact be slower than an 8 car train at times.

Okay guys, not being an electrical engineer, this discussion is way over my head; I only have a very simple understanding of air brake systems. So can you guys explain in layman's English why we don't hear the whoosh when the brakes release on M-7's? I do like that high pitched whine when they start up though.

BTW Phil, did you say something in the NJ thread about hanging out at Mineola nowadays? If so, maybe we should meet there for coffee! Chuckle. :D

Head End - my bike's at the bike doctor now awaiting word on why the evil red oil light won't go away. Should be back in < 2 weeks. Hey, this summer? sure. I'm bored until I find a job (I've not yet decided if I wanna put in at the LIRR, frankly, I want to gt off LI altogether now though...)

Head-end view,

Two possibilities for the lack of "whoosh" when M-7 brakes release quickly come to my mind.
First, there are 2 air brake control units (POU- Pneumatic Operating Unit) per car on the M-7. One for each truck. Each one incorporates electronic control and pneumatic valves and ports. The M-1 and M-3 have only one air brake pneumatic unit ("G-4" or "G-4a" unit) per car. So, all your air is coming out of one port on the older equipment. It is divided between 2 ports on the M-7.
Second, M-7s operate with less air in the brake cylinders because there are tread brakes and disc brakes. Depending on car load weight, a light M-7 may have 43-46 psi brake application pressure when at a standstill....a light M-1 or M-3 (they only have tread brake units) will have around 70 psi brake application pressure when at a standstill.
You can quickly surmise that a 43 psi brake release through 2 ports will be quieter than a 70 psi brake release through 1 port.

There is some noise when an M-7 releases. You really have to listen for it, though. It's kind of a wimpy "shhhhhh".


Tom

the vents on M7's also still have all the bee shields still on the M1 /3's most of them are missing.
these are also the plug to plug a defective valve.

Dutch,

Yeah, man.
They moved the CMVs and EMVs on the M-7s just to confuse us.
The M-7 EMV has a cutout handle inside the car, though. You don't have to go outside and try to find a plug maybe 6 cars back.
BCCO (J-bar equivalent) and SBCO (EP cutout equivalent) are also inside the cars on the M-7. Note that each truck on an M-7 has an SBCO because each truck has it's own operating unit. You can "EP" one truck in a 7.

Hopefully, the inside-the-car cutouts in the M-7s will work better than the lame attempt at the inside-the-car EP cutout that the M-3 has.

Tom

Bah, I still liked the whoosh better. You KNEW you missed your train when you heard that!

"This is a bit off topic. If all of the shoes in a car are live when one third rail shoe touches the third rail, how did passengers avoid injury or electrocution when boarding an electric MU car on a low platform? Were people just more careful then or were injuries underreported?"

If you look at some old photos of low level platforms, usually there was a protection board at the edge, flush with the top of the platform. This way passengers couldn't come in contact with the shoe.

N340: Thanks for that explanation. Makes sense.

Bill N: I thought the 3rd rail was usually (if not always) between the tracks away from the platform at stations, wasn't it? Obviously you couldn't have the public safely stepping that close to it.

But ya' do have a point about the shoe though. I was a kid back in the days of low platforms in electric territory, but I don't remember ever hearing about any passengers getting electrocuted by accidently touching one.

I've asked this before without getting an answer, beneath the electrical intelectuals, I suppose. Could a portable DC generator (supplying 700 volts?) be built, fit on one car, and placed on a M-1,3,7 to supply power in areas where there is no 3rd rail? Would it be practical? Thank-you keeper of the diodes....

thrdkilr,

Actually, I've never seen that question asked. I missed it somehow.

Bear in mind, I'm not an Electrical Engineer. I only fix what's already been designed by people much smarter than I. (Well, most of the time, anyway. Some of my ideas are better than the existing designs. Perhaps with 20/20 hindsight as advantage, in some cases.)
With that caveat understood, some opinions:
A generator putting out 750VDC is no problem. The amperage requirement could be a problem. The unit would likely be too heavy to be truly portable. Also, the 750VDC buss line on all LIRR EMU cars is contiguous to a pair of cars. You would need to apply one of your generators to each pair of cars, or rewire each pair of cars with receptacles to buss the 750 between pairs of cars. In that case, your generator would have to be even larger and heavier, to provide a trainline hotel power type of setup.
There could also a problem with carrying fuel in the East River tunnels. AFAIK, it's generally frowned upon by FDNY. (At least, it used to be.)
Obviously, they worked it out satisfactorily to let the DMs into the tunnels. (There may be other RR's equipment using the East River and Hudson tubes carrying fuel....guys?? How about MNCR into GCT?) They may not like all the EMU cars running around with fuel tanks, however.
Perhaps Dutch or one of the rules and regulations savvy guys can shed some light on what requirements have to be met to carry fuel in the tunnels.
The [possible] fuel issue could be circumvented if you're talking about running your consists from no further west than Woodside, or more realistically, Jamaica. But then we're talking about a two seat ride to Penn anyway...not something commuters like.

Interesting prospect, though. Seeing a line of M-7s chilling at Montauk. I like it!!

i once proposed on the Septic forum an alternative to the silly proposed dual mode service one organization was pushing - dual mode MU pairs.

In such a system, you'd have one (dedicated) diesel MU, and one (dedicated) electric MU. In diesel territory, the diesel would pull you, in electric, the electric, though the diesel could act as a 'booster' for higher performance or if an electric didn't come on. At least until the tunnels.

The CRC DMU, though hardly ideal and hardly optimized, is 1200 HP. If an M-7 could pull a dead unit - there's your answer, though I suspect that in the end, the whole setup would simply be too heavy for an 1:1 ratio of live Vs dead units, though 2 electrics per diesel would work (though the diesel performanmce would be less - but much better than the current DE/DMs, by far)

I've also thought of fuel cell based units, where on third rail, they'd generate and store hydrogen, then off third rail they'd run off the fuel cell (and store the water). Complex, expensive as heck, but technically possible. I don't know how the NYFD would feel about hydrogen on board trains, though it's theoretically safer to store than diesel or propane, etc.

There is no rule against fuel in tunnels not even in New York. newer equipment can be built with fuel cells in side the fuel tanks or sponge type foam were fuel is actualy safe incase of derailment and puncture.
feeding a few M1's with Gasturbines was tried but not very succesfull and LIRR was sorry they even got involved in the DOT study.
with a M1 or M3 needing near 600 HP per car plus power for heat/ac and MA the power generation needs to be about 1400 hp per two cars or even more for maximum performance.