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Maserati7200

Evidence That The R62/A's and R68/A's Will Be Rebuilt Soon

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That document doesn't prove anything. This is a set of recommendations, it's just the results of a study, so this is basically a "pipe dream for a pipe dream" because even if it makes it all the way into a capital plan, that doesn't mean it will happen, and it hasnt even done that yet.

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It is page 31 and it said the R-44 to R-160 existing fleets are capable of being overhauled and have a regenrative energy component... The 'concept or future R-179 and R-188 is also capable of having regeneratvie energy, :)!

 

Eh... not quite. Only the NTTs have regenerative braking. The SMEEs don't. However, this plan suggests that all cars be made lighter, not alluding to a full rebuilding.

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Yes, when breaking from any speed above 10-15 mph, they use dynamics. Once they are under 10-15 mph then the air breaks take over. The heat created by the dynamic breaks is dispersed through the resistor grids. I think it was the R15s or R17s that would send a blast of hot air out from under the cars when they stopped at stations, getting the geese on the platform.

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Well lightweighting... interesting...

** Note: R188 class “new cars” are actually composed of 386 new chassis, and 120 R142a up-converted chassis, however this does not materially impact key performance

metrics such as cost, CO2, or energy savings

I found this on Page 31

 

Also:

Note: * Regenerative capable fleet is 4182 cars = 2270 existing fleet + 382 R160 Op2 +1530 R179, R188

1530 new cars (aside from R160s)? Wow

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Whoops. I meant page 31.

 

~ 2000 lbs per car average weight reduction must be applied to

4800 car overhaul eligible fleet and all 1500 new build cars

Average regeneration of 3.75 kWh per stop, per 10 car train

required for the 4182 regencapable fleet*

Implies that 31% of the regencapable fleet must have full 12 kWh

on-board energy storage (1300 cars)

Optimal regeneration requires special train braking performance

(moderate stop)

All Reasonable LightweightingTechnology (2.5% reduction)

Moderate Regeneration

Performance (7.5 % reduction)

by on-board energy storage

 

This clearly shows that the "overhaul eligible fleet" (which I think is R62/A's and R68/A's because the R44 and R46 are leaving in a few years time. I assume they will get new trucks. If this actually happens, the R68/A might not be slow anymore.

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Whoops. I meant page 31.

 

 

 

This clearly shows that the "overhaul eligible fleet" (which I think is R62/A's and R68/A's because the R44 and R46 are leaving in a few years time. I assume they will get new trucks. If this actually happens, the R68/A might not be slow anymore.

 

And lighter.

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you wish... about the R68's being not slow, it would kill the spirit of that car class. it wouldn't be the r68 any more. and what are we talking about here? AC propulsion?

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Yes, when breaking from any speed above 10-15 mph, they use dynamics. Once they are under 10-15 mph then the air breaks take over.

 

No air brakes at all over 10-15 mph, or in conjunction with the dynamics?

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Well lightweighting... interesting...

 

I found this on Page 31

 

Also:

 

1530 new cars (aside from R160s)? Wow

 

well, 506 R188's, and 1024 R179's. cant wait for those...

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Don't under estimate the power of dynamic breaks, thats what frieght trains use to control speeds on steep down grades. As to air breaks above 15-20 mph, I don't know but I can find out.

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Don't under estimate the power of dynamic breaks, thats what frieght trains use to control speeds on steep down grades. As to air breaks above 15-20 mph, I don't know but I can find out.

 

Hey hey! I ain't dissin' the air brake! B) You definitely sound like you know your subway mechanics.

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I know some of the stuff on how subway and trolley cars work. I do volunteer up at BERA working on the cars. One benefit, of many, the other guys that work there know more then I could ever wish to know and they are more then willing to share there knowledge.

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you wish... about the R68's being not slow, it would kill the spirit of that car class. it wouldn't be the r68 any more. and what are we talking about here? AC propulsion?

 

No, its to get the cars to be lightweight, and more energy efficient. I'm pretty sure that it would require newer trucks.

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No air brakes at all over 10-15 mph, or in conjunction with the dynamics?

 

A motor must be functioning properly for the dynamic brake to work. That's why if you see the amber light signalling a "dead motor" at one end of a car, odds are that car will be squealing into the station as it stops, because the dead motor means the dynamics can't work so friction braking kicks in.

 

When everything is working properly, above that speed there is ONLY dynamic braking, this is done because it is generally smoother than friction braking and in addition to that it doesn't wear out the brake shoes and rigging. As the train slows down and approaches the speed where dynamics taper off and friction braking kicks in to make the final stop (this is done because dynamics can't reasonably bring a slow moving train to a stop), there is a brief transition period where one is kicking in and the other is dropping out, so it can be in conjunction but generally speaking you want one or the other - dynamics at high speed, friction at low speed.

 

On the older SMEE trains, they could really stop, there was an inshot valve that allowed a T/O who made a large brake request to use dynamics and friction at the same time to rapidly bring his train to a stop, but those were removed.

 

Dynamics also require a T/O to still know what he's doing, if he starts fanning the brakes (taking brake, then releasing it, then taking it, then releasing and so on..), he will lose dynamics and go into friction braking a lot sooner than he should which increases wear on key brake parts.

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So that explains why T/O's generally take a large chunk of brake to stop the train, whereas with an automobile you would use the brakes more intermittently?

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No, its to get the cars to be lightweight, and more energy efficient. I'm pretty sure that it would require newer trucks.

 

well, to regenerate power and feed it back into the system, you need AC propulsion, since DC doesn't cut it when it comes to regeneration.

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So that explains why T/O's generally take a large chunk of brake to stop the train, whereas with an automobile you would use the brakes more intermittently?

 

Yup that's part of it...it also has to do with the physics of how a train slows down when brake is grabbed. At higher speeds, MUCH more braking effort is required to stop a train, but at lower speeds that's not the case. The amount of air that feels smooth at 35 MPH will throw a free standing passenger on the floor at 2 MPH. As a train enters a station, it's better to grab too much and undershoot, then back off a little bit to smooth out the stop, coasting up to the marker if need be. It's much harder to grab too little break, have to grab more, and make the stop because the stop can be rough or you could overrun the mark.

 

Ideally a large initial brake application is taken, the train starts to slow down, then the T/O lightens the application, but never fully releases the brakes, to smooth out the stop and hits the marker perfectly.

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