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 Kurt
 
I know that the M1a and M3a can run together, but it was stated that they have different acceleration rates, making the ride rough at times. Lately I have noticed trains on the Harlem line with M3a'a on the north end, and M1a's on the south end. Is this because there are less M1a's still in service, or just something random?

  by DutchRailnut
 
It is beacause we have a few yardmasters who make up their own minds and despite complaints from crews and passengers don't give a rats a** about how rough the train handles or how the passengers feel.
And managment does not care cause on paper their compatible.
In practice the M3's with 43% acceleration rate and M1's at 60% do not mach the same braking and powering curves.
only if both cars are running unrestricted do they match like on LIRR.

  by Nester
 
Why are the M3As more restricted than the M1As?

  by Penn Central
 
Nester wrote:Why are the M3As more restricted than the M1As?
They aren't restricted but have slower acceleration because of additional weight. The major factor in the added weight is traction motor cooling fans (that the M-1 does not have). When they are coupled to an M-1, the M-1 will accelerate at a faster rate, putting more load on the M-1 traction motors than the M-3s in the same consist. The traction motors heat up, and that's not good.

Another difference between the M-1s and M-3s is braking. Just as the M-3 can't match an M-1 in acceleration, the dynamic braking can't slow the addtional weight at the same rate. To do this, the M-3s have higher brake cylinder (tread brake) pressure. When you mix cars with dynamic and friction braking, it isn't a comfortable ride.

In theory, the M-3s could accelerate as fast as the M-1s but the cost to move the additional weight at the same rate of acceleration would use a lot more energy. The M-7 can run away from an M-1 or M-3 but they do not operate at the maximum rate for the same reason. The energy cost would be too high.

  by Nester
 
Penn Central wrote:
Nester wrote:Why are the M3As more restricted than the M1As?
They aren't restricted but have slower acceleration because of additional weight.
Thanks, that was the answer I was looking for -- it was Dutch's use of the word "unrestricted" that confused me.

  by Terrapin Station
 
Penn Central wrote:
Nester wrote:Why are the M3As more restricted than the M1As?
Another difference between the M-1s and M-3s is braking. Just as the M-3 can't match an M-1 in acceleration, the dynamic braking can't slow the addtional weight at the same rate. To do this, the M-3s have higher brake cylinder (tread brake) pressure. When you mix cars with dynamic and friction braking, it isn't a comfortable ride.
Ah, that explains the rough ride that I only encounter once in a very great while. Next time it happens I'll have to see if it is a mixed consist.

  by MisterM7
 
It is true that the M1 and M3 cars have different acceleration and braking rates. I asked why on the LIRR the cars are mixed as they are. I was told that it has to do with the daily amount of trains run and schedule complexities that prevent dedicated M1 M3 consists.

With more M7s coming on the property (7578 is the highest car # I have seen to date) the M1/M3 cars are beginning to show up sporadically in dedicated consists.

I had a 10 car M3 train that ran GREAT! It also ran better than the 10 car M7 train I was next to on the mainline from Jamaica to Woodside. Both trains were exp from Jamaica to Penn with clear signals all the way to Harold.