Discussion relating to the operations of MTA MetroNorth Railroad including west of Hudson operations and discussion of CtDOT sponsored rail operations such as Shore Line East and the Springfield to New Haven Hartford Line

Moderators: GirlOnTheTrain, nomis, FL9AC, Jeff Smith

  by Stephen B. Carey
 
Just a question, recently while looking at photos I have noticed that the Metro-North M7's are designated M7-a's. How does this make them different from the LIRR M7's. Im guessing its only the difference in third rail shoe but are there any other differences? (besides paint of course.)

  by DutchRailnut
 
Different interior setup, Differend third rail setup, Different Cab signal setup, Different airconditioning modifications.

  by Lirr168
 
Dutch,

I was aware of the cab signaling, third rail shoes and air conditioning, but the interior thing is new to me. What exactly is different?

  by Nester
 
In the middle of the car,


M7 seats face in toward the center of the car

M7-A seats face the ends of the cars.

In addition, M7-A cars have the leather/padding on the rear of the seats like other MN gear. M7s don't have this feature/amenity.

Nester

  by Noel Weaver
 
Nester wrote:In the middle of the car,


M7 seats face in toward the center of the car

M7-A seats face the ends of the cars.

In addition, M7-A cars have the leather/padding on the rear of the seats like other MN gear. M7s don't have this feature/amenity.

Nester
MY GOODNESS, You are all very observent. :wink: :wink:

Noel Weaver

  by Stephen B. Carey
 
That acctually was quite a few more differences than I was expecting. Thanks.
  by N340SG
 
The biggest differences have already been mentioned. There are other differences as well, but the average passenger may never see them. Certain door operations are different, I'm told (Crew Door, Door Partial Open), which are probably simple software changes to the same door control computer modules.
MN has the blue light feature in the cabs to indicate someone is working on the consist; LIRR does not.
MN opted to have quick- disconnect "Clam Shells" for the trucks; LIRR did not.

Can't think of any others right now.

Tom
  by Kurt
 
LIRR M7s have plastic number boards that look like they can be illuminated, and the car body has some type of external brace in the center of the car.

MNRR M7a have number stenciled directly to the car body, which does not have the external bracing.

Does anyone know why LIRR M7s have this extra reinforcement?
  by N340SG
 
Kurt,

LIRR M-7s have a single U-shaped fluorescent bulb behind the number board. We've had to replace several of them already. The M-1s and M-3s have 3 incandescent bulbs behind each number board. At least when one or two bulbs blew or loosened, one could still see the number at night.

I can't state authoritively why the rub strips are on the LIRR M-7s, but I suspect they wanted them because there have been quite a number of the older cars rubbing on the bench walls in the East River tunnels over the years. Please note that's just my opinion.

Tom
  by jtr1962
 
N340SG wrote:LIRR M-7s have a single U-shaped fluorescent bulb behind the number board. We've had to replace several of them already. The M-1s and M-3s have 3 incandescent bulbs behind each number board. At least when one or two bulbs blew or loosened, one could still see the number at night.
Why aren't they using white LEDs for this instead of fluorescents? I suspect several possibilities here. Maybe the driver circuits are faulty if the fluorescents are burning out too frequently, maybe they're just turned on and off too often, or maybe the vibrations are causing the filaments to break (yes, fluorescent tubes have filaments which aid in starting and are covered with material to help maintain an arc). BTW, nobody in their right mind would design something with incandescents nowadays even if they were used on the M1/M3. Besides the short life (which means a fortune on maintainance), they give a crappy yellow, uneven light when used in something like a number board. I hate them even for general room lighting as the ugly yellow light distorts colors and makes me squint. LEDs are really the way to go here. With a properly designed driving circuit, LEDs can last 100,000 hours compared to 20,000 for fluorescent and 750 for incandescent. They also don't suffer shortened life when turned on and off frequently as fluorescents do, nor are they affected by vibrations. Soon LEDs will even be bright enough for headlights (including train headlights). I'm currently working on an LED retrofit for fluorescents used in taxi ad signs. The fluorescent tubes were suffering premature failures because of the temperature and vibration extremes of a moving vehicle. Remember that LEDs have been increasingly used with great success in mass transit for the last decade or more. Maybe that's ultimately the way to go here.

  by N340SG
 
We've had to replace more than a few of the LED arrays on our M-7s already. I don't know if they are just poor quality, or if the rigors of train use affects them. They do not seem to be holding up to the hype of many years of trouble-free service.
Did have a couple come back on with the good old punch- the- panel trick, however. :P

  by jtr1962
 
N340SG wrote:We've had to replace more than a few of the LED arrays on our M-7s already. I don't know if they are just poor quality, or if the rigors of train use affects them.
Sounds like poor circuit design to me and/or maybe poor assembly. For the same reasons some municipalities had such poor experience with LED traffic light retrofits that they actually went back to incandescent. The problems including poor filtering, lack of surge protection, and even poor solder joints. A railroad is an application where plenty of surges and spikes exist. Since LEDs are susceptible to these, the driving circuit needs to offer protection. I've seen driving circuits which were little more than a diode and a resistor. Small wonder the LEDs failed. I always use adequate capacitive filtering and drive the LEDs via a constant current circuit. Unlike incandescents, LEDs are current-based, not voltage-based. Vf for a typical 5mm white LED can vary from 3.0 to 3.8 volts when driven at the recommended 20 mA. Since it's a diode, even a tenth of a volt increase can double the current. Therefore, you can't say I'm going to give the LED x volts. Vf of LEDs, even from the same manufacturer, vary all over the place. You need to make a circuit which pumps a constant current into the LED regardless of Vf. Many designs I've seen simply don't do this in order to save a few pennies. This ends up giving a bad impression of LEDs to the user when the fault really lies with the designer.
  by Penn Central
 
Stephen B. Carey wrote:Just a question, recently while looking at photos I have noticed that the Metro-North M7's are designated M7-a's. How does this make them different from the LIRR M7's. Im guessing its only the difference in third rail shoe but are there any other differences? (besides paint of course.)
Another major difference is:

Truck modifications for a smoother ride (note the large shock on the side of the MN cars)

  by DutchRailnut
 
yes the yaw damper, almost all MNCR cars came factory equipped , the later LIRR cars did too, but the first 100 or so LIRR cars are being modified with the yawdampers at LIRR during modifications.
the Yaw dampers stop the rolling motion of carbody caused by truck hunting.

  by MACTRAXX
 
I'm suprised that no one mentioned the obvious front end differences-the LIRR version having the yellow stripe(which I HATE-I would have used RED) and the MNCR version having the zebra stripe graphics(just two paralleling white stripes on the top and bottom of the stripe area of the same decal width would have been sufficient) which to me is overkill.The MNCR car should have front numbers above the doors just like the LIRR car. The LIRR #sign light is a good touch - when the M3s get overhauled with the new interior like the prototype test pair,replace the #sign bulbs with either led or flourescents. In the MNCR M7 door area,flashing strobe lights that work when the doors are being closed were installed but not on the LIRR version. 7000 series LIRR vs. 4000 MNCR series #s also. One final thing-why are the MNCR M7s being fitted with the large air intake-if that is what it is-on the roof while the LIRR car does not have? Some questions and observations from MACTRAXX