Trolley Running - Well, Sort of...(Mattapan High Speed Line)

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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby jamesinclair » Sun Sep 14, 2008 3:39 pm

Gerry6309 wrote: A much more important issue is the loop on the Ashmont Viaduct which is a very tight radius - maybe too tight for articulated cars. The trucks on some of the PCCs object loudly to the curve. The design may be deliberate, since there would be no need for articulated cars here anyway.
.


If the PCC can do it, then an articulated car would actually have an easier time making the curve.

Picture a 2 PCC train making the curve. Its the exact same thing.
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby Gerry6309 » Mon Sep 15, 2008 11:28 am

jamesinclair wrote:
Gerry6309 wrote: A much more important issue is the loop on the Ashmont Viaduct which is a very tight radius - maybe too tight for articulated cars. The trucks on some of the PCCs object loudly to the curve. The design may be deliberate, since there would be no need for articulated cars here anyway.
.


If the PCC can do it, then an articulated car would actually have an easier time making the curve.

Picture a 2 PCC train making the curve. Its the exact same thing.


Now take the tapered ends of the PCC and square them off, then shorten the length of the coupling. You will have a better idea of how it works. To get more bend, shorten the overhang. When you have lost 1/2 a car length you have an LRV or Type 7. The Type 8 gains a little length with a double articulation. This is necessary for the Green Line, not for ASH-PAN. Do you want 15 minute peak headways? (Unless your name is Tom McLernon)
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The next stop is Washington. Change for Forest Hills Trains on the Winter St. Platform, and Everett Trains on the Summer St. Platform. This is an Ashmont train, change for Braintree at Columbia.
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby MBTA3247 » Tue Nov 04, 2008 7:43 pm

3254 was having brake issues this afternoon, apparently related to the dynamic (I think?) brake. The car started braking very abruptly a few seconds after the motorman took his foot off the power pedal several times between Ashmont and Butler. It actually seemed like the control system was bucking the motors.
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby typesix » Tue Nov 04, 2008 7:46 pm

It's called "plugging" when the car acts like that.
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby Disney Guy » Tue Nov 04, 2008 8:14 pm

MBTA3247 wrote:3254 was having brake issues this afternoon, apparently related to the dynamic (I think?) brake. The car started braking very abruptly a few seconds after the motorman took his foot off the power pedal several times between Ashmont and Butler.

Was this just after starting up or had the car been moving for awhile?

Now plugging may be abnormal in any circumstance but I did recall that Seashore's ex-SEPTA PCC #2709 plugs if you start up with the power pedal down part way and a few seconds later let up on the pedal as if to want to go really slowly. Someone was saying that the controller (which is not visible to the operator) has to go up a few notches and (on 2709) depressing the power pedal to the floor for at least a moment before letting it up also accomplishes this.

If the car had been moving for awhile (and got up any speed), then plugging would result in a very uncomfortable ride.
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby Gerry6309 » Wed Nov 19, 2008 4:53 pm

Plugging at low speeds can occur if the timing of the switches is a little off. Once some speed gets up either the Limit Relay is missing an input or the dynamic braking resistance is open at some point in the circuit. 3254 is a recurring troublemaker, possibly from frequent use as a pusher.

3263 was added to the A/C list as of mid October. Health concerns have kept me off the line for a while - will update soon.
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The next stop is Washington. Change for Forest Hills Trains on the Winter St. Platform, and Everett Trains on the Summer St. Platform. This is an Ashmont train, change for Braintree at Columbia.
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby rfp2 » Thu Nov 20, 2008 9:11 am

Gerry,
You have been missed. Please be well.
Ron
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby MBTA3247 » Wed Dec 03, 2008 2:09 pm

Anyone know what's different/wrong about 3230's mechanical systems? Pretty much every sound it makes and the way it rides is different from every other car on the Mattapan Line. It constantly vibrates while moving, sounding like the gears in the trucks are grinding away at each other, and there's another sound I can't place that ramps up and down over a period of 4 seconds or so. For people standing beside the car, there's an odd hum like a fan or something coming from the vicinity of the air compressor.
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby Gerry6309 » Thu Jan 22, 2009 3:47 pm

Gerry6309 wrote:3263 was added to the A/C list as of mid October. Health concerns have kept me off the line for a while - will update soon.

...Well between that and other issues, this is a long overdue update!

3263 was actually returned to service on the 25th of September. It was replaced in the shop by 3268 which was completed on October 18th, and followed by 3254 which was completed in mid-December. The last active car (and the oldest) with the original fans, 3087, was taken out of service around that time, and is presently about 90% complete. The interior still has to be put back together and testing completed. Car 3260 has had its accident damage repaired at Riverside and now sports a new paint job. It will probably return to Mattapan when 3087 is complete. The new HVAC system will then be installed.

3230 is presently out of service awaiting a rebuilt MG set from Everett. The remaining 7 cars are holding up well this winter with none of the failures encountered last year after the layup. I rode 3262 and 3268 today, Both were running smoothly with no plugging or other troubles.

A recurring problem on the line has been flat wheels caused by a combination of plugging and slippery rail. The former has been eliminated through effective maintenance, and a recent weekend shutdown attacked the latter in a big way. Four bucket trucks descended on the right of way and most of the overhanging trees were pruned back or cut down. Undergrowth was also attacked at places such as Capen Street and Cedar Grove Cemetary to improve sight lines and preven rear enders. This issue was was brought to a head in June when a branch fell and damaged 3260. Most abutters are happy with the work, but at least one tree-hugging NIMBY tried to have it stopped. The state Conservation Agency which owns the adjacent Neponset River Reservation is working with the T on this one , so that no unnecesary trees are cut. As a result, the "Milton Subway" now sees full daylight for the first time in some 20 years.

The squeal of the wheels at the new Ashmont Loop-remains an issue for now. Aside from rebuilding the loop with a wider radius, the only possible solution might be a return to resilient (rubber sandwich) wheels. These were eliminated as a maintenance headache in the 1960s, but reintroduced on newer cars in the 70s.

Despite the copious amounts of snow this winter, the line has operated with few problems, mostly as a result of (as the Boy Scouts would say) being prepared.
Gerry. STM/BSRA

The next stop is Washington. Change for Forest Hills Trains on the Winter St. Platform, and Everett Trains on the Summer St. Platform. This is an Ashmont train, change for Braintree at Columbia.
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby RailBus63 » Fri Jan 23, 2009 1:08 pm

Regarding the squealing wheels - is there any reason why the same wheels used on Type 7 or Type 8 cars cannot be used on the PCC's? Are they a different size?
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby typesix » Fri Jan 23, 2009 5:07 pm

Resilient wheels of the type used on the T7 and T8 could be used on the PCCs. The size would be different, but same design. However, this will never happen, the T has stated that they have plenty of solid steel wheels in stock for the PCCs.
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby Gerry6309 » Fri Jan 23, 2009 5:38 pm

The homeowners, or should I say mansion owners, east of Ashmont Station may bring their political will to bear on the MBTA. I can hear the cars looping over a half-mile away - with my windows closed. I never could before, except on the quietest summer night with the windows open. The sound must be brutal up close every 12 minutes until 1 AM and starting again at 5:20.
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The next stop is Washington. Change for Forest Hills Trains on the Winter St. Platform, and Everett Trains on the Summer St. Platform. This is an Ashmont train, change for Braintree at Columbia.
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby diburning » Fri Jan 23, 2009 6:43 pm

Are they greasing the loop?
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby 3rdrail » Fri Jan 23, 2009 6:57 pm

Whether it's at Ashmont or the famous Dudley curve, what is that sound generally ? Is it inside wheel flanges rubbing up against a restraining rail, un-synched wheel treads on one side of a curve spinning (or dragging) on the rail head, or the outside flange rubbing on the side of the rail ? The funny thing about almost any sound is that if you live near it, after a short while you usually don't even hear it anymore. I grew up just outside of Forest Hills, mere feet from New Haven's / Penn Central's Boston-Providence Main Line. Those diesels (no juice then) raced by doing 80 MPH or so. We kind of "heard" them, but didn't. It never was a bother, and I'm not addressing that fact as a rail buff. Nobody in my family ever even mentioned it.
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Re: Trolley Running - Well, Sort of...(Mattapan High Speed Line)

Postby Gerry6309 » Fri Jan 23, 2009 7:43 pm

The squeal comes from the fact that both wheels travel at the same speed but one is on a much shorter rail than the other. The normal way to combat this is to make the track gauge a little wide on the curve. This causesthe inner wheel to rest on the guard rail, which is heavily greased so the wheel slips. The outer rail is kept dry insuring good traction. The inner wheel tread rubs slightly on its rail creating a fairly constant vibration which varies in volume and pitch depending on speed. The resilient wheels used on the newer cars, and on the PCCs until the 1960s, contain rubber pads which dampen the vibrations and reduce the volume. The solid steel wheels are dished, and act like the surface of a bell, amplifying the sound. Tap a solid steel wheel suspended by the axle on the edge and it will ring just like a bell. The PCC wheels have a natural resonance which mimics the vibrations from sliding on the curve, making the sound worse. All because the MTA didn't want to torque the nuts on every inspection!. The wheels used on the newer cars use a design without nuts, eliminating the maintenance headache. One PCC was equipped in the 70s to test the design. (a picture window car IIRC) Another had a competitor's design.
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The next stop is Washington. Change for Forest Hills Trains on the Winter St. Platform, and Everett Trains on the Summer St. Platform. This is an Ashmont train, change for Braintree at Columbia.
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