Toronto Union Pearson Express | ?m | ?s | Metrolinx | MMM Group Limited
steveintoronto
Superstar
That explains a lot. Must be due to regenerative braking, albeit how that's done without electric traction motors I don't fully understand. It must be a balance between dynamic braking and throttle in one controller, but without the ability to jostle the two, something older car drivers with standard xmssns learned years ago, (double footing) and loco engineers have done forever. If the technician doesn't set that joy-stick up right, then no wonder it gets grabby. I suspect all feel is removed, and the joystick just controls software that's apportioned to one or the other with a fixed overlap...or gap.
Been Googling to get any kind of description on how the Sharyos regenerate their power, I can find absolutely nothing. All I can think of is that they mechanically/hydraulically de-clutch the prime mover, and the drive shaft is coupled through to a generator. But if that's the case, I fail to understand their spiel of reclaiming some (IIRC) "10 to 20% of wasted energy". You could run a pizza operation with that much energy. A hybrid, (by definition a DEMU) yes, absolutely, but not a DMU. And a DEMU could then use that accumulated braking energy for acceleration, like a hybrid car.
Just Googling, and didn't find the answer I was looking for but just found this, as per mention from another poster weeks back on the sharp curves at Airport Junction and undue wear on the bogies and cardan shafts, thus precipitating the banging and rattle in the coach above the driven bogie:
http://www.tcrponline.org/PDFDocuments/TCRP RPT 52-D.PDF Chapter 4, Pg 19
I'd love to find a spec sheet of the Sharyo DMUs...and schematics.
In case the point on the tight radii at airport curve isn't clear, it appears the design was intended for EMU, not DMU, or DEMU with electric traction motors mounted directly on the bogies. That speed restriction was presumed to be for safety on the curves. Looks like it's for reasons of mechanical stress. Scarborough RT redux?
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vegeta_skyline
Senior Member
It's quite frustrating indeed how precious little data there seems to be available on the Sharyos online. One of the best resources I've found is this link from SMART which you've probably seen before. It gives a good general overview of the trains specs but is still short on specifics.
http://www2.sonomamarintrain.org/userfiles/file/Vehicles -Draft DMU Technical Specification 1-20-10.pdf
On that note, they're removed two of the additional temporary slow orders they placed on those curves but only for the West track. The first for the curve by the airport and the second for the curve at the base of the viaduct just before the Pearson sub merges with the Weston. The speed is still limited by PSO to 25mph and the 15mph TSO's remain for the east(inside) track.
I received some information a while back as to why the TSO's were removed for the west track yet still kept on the east, but for the love of god I cannot remember what that reason was at the moment.
http://www2.sonomamarintrain.org/userfiles/file/Vehicles -Draft DMU Technical Specification 1-20-10.pdf
On that note, they're removed two of the additional temporary slow orders they placed on those curves but only for the West track. The first for the curve by the airport and the second for the curve at the base of the viaduct just before the Pearson sub merges with the Weston. The speed is still limited by PSO to 25mph and the 15mph TSO's remain for the east(inside) track.
I received some information a while back as to why the TSO's were removed for the west track yet still kept on the east, but for the love of god I cannot remember what that reason was at the moment.
rbt
Senior Member
I love how she says that like it's a good thing.
It is good news. The #1 complaint from people who didn't take the service was that the trains looked empty; they no longer look empty.
Also, standing room only will allow them to slowly ratchet the price back up to push commuters back onto GO trains.
steveintoronto
Superstar
I studied that pretty closely months back, it's the one where they 'forbid' the xmssn being anything but fluid throughout. I'll find and quote that tomorrow. It's important, as Metrolinx paid SMART hundreds of thousands of $ to prototype the design. And then MX decided to opt for the ZF 6 spd mechanical gearbox....???
Because on the same radius, the rate of angle vector of the wheel flange against the rail is greater on the inside (the radius is shorter) and thus per given axle separation, the mismatch of flange angle to the rail is greater. Unless you have steerable axles, which those bogies certainly don't. They may have relaxed the speed-order somewhat as the rail inside faces wear, and so the gauge loosens just enough to reduce the rate of scrubbing. Unless they grease the rail head insides, they must squeal something awful. The real wear though will be on the cardan shafts, couplings and mating gears on the bogie as they're wrenched close to a right angle under applied torque. Also the inside (east) track would produce much greater wheel-speed differential so the wear factor would increase geometrically unless speed is reduced arithmetically. Think about the rear wheels on your car as you do a tighter v. wider turn. In a really tight turn, the inside wheel will be barely turning, the outside will. The car has a huge advantage v. a train though, it has a differential. A posi-traction rear axle locked will actually hop in a tight turn.
It's a real mixed blessing! Something that must be made clear though is that since airport travellers are paying a premium, they are the ones that should get space for their baggage, and first shot at seats.
It's Hobson's Choice though. It might have to come down to having platform staff at the intermediate stations loading on passengers, with a head count of what's coming down the line. Unfortunately, that will slow loading....but this situation can only compound during peak times unless some sort of seniority is given to the airport travellers....or only charge them at the GO rate if that can't be managed. It's great the trains are filling up, it's not great that passengers pay a different rate for the same product. (And by same rate, I mean calculated by distance).
Which brings us back to the conundrum of how to increase the fleet. I don't think many if any posters favour buying more Sharyos.
Ideas?
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vegeta_skyline
Senior Member
I was being somewhat sarcastic, yes in this case it is good news. But in a general sense congested trains are not a good thing. I don't agree with increasing the set price, the trains are still fairly empty outside of the peak travel periods for commuters and air travelers. That ridership can grow in time but only if the price remains near to where it currently stands. I think surge pricing would be the best solution, but I'm not exactly confident that's something they can implement properly or if its something they would even look at.
steveintoronto
Superstar
Or with the higher price air passengers pay, they get a priority ticket, which may or may not guarantee a seat, but certainly they get to board, and the GO fare clients have to default until the next one, or GO. It might give a new use to the UPX Presto machines that they automatically book reserved boarding, even at the intermediate stations, albeit it might take staff to check them to allow boarding.
Something has to give.
vegeta_skyline
Senior Member
Definitely an eye raising decision on their part.
With regards to the whole east track vs west track slow order, indeed it makes perfect sense as to why it's being kept on the inside track. The most curious thing about it though is with how long it seems to have taken the powers that be to realize this. The slow order was the same for both tracks for many months.
Sadly the same can be said at places far from where trains are actually operating it seems.
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rbt
Senior Member
Agreed entirely; but this line went from having a purpose to being driven exclusively by politics. I've had 3 people mention to me how nice it is to see it full (while they pass it on their Barrie/Milton train). So politically, overcrowding on UPX is a good thing as the voter seems to believe the cost is justifiable now and wasn't before.
I suspect underbuilding is going to be a permanent target for the province going forward; clearly it's preferred by those who vote (we could have been demanding much more commuter service on that line; 90% of the infrastructure is there now).
It's mostly commuters that I'm concerned with (trips not using Pearson Airport). I don't want travellers with bags to find themselves unable to board in a year. If airport bound passengers manage to fill the train, then it's time to look at capacity expansion.
crs1026
Superstar
The elegant solution will emerge once ST/RER arrives. Non-airport passengers will have an option - and with ST, perhaps a break on fare.
I support ratcheting up the fare to manage demand. We go a little overboard with people wanting fares to be 'affordabe' (as if subsidies for the remainder fall from the sky). Price points should not give the service away. Just because ML got the fare wrong at the start doesn't mean we push the pendulum too far in the opposite direction.
- Paul
steveintoronto
Superstar
vegeta_skyline said: ↑
I replied:
Here's the only reference I can find to "regenerat" (or)(ive)(ion)(ed)
In all fairness, this is still a proposal to tender, but look at how this *could have been done*:
I'll pore over this report later. Any more where this came from Vegeta? What an eye-opener.
http://www2.sonomamarintrain.org/userfiles/file/Vehicles -Draft DMU Technical Specification 1-20-10.pdf
I replied:
In fact, now I scan through it, I see it's a later one and I have to correct my claim on "forbid" using a mechanical xmssn, that was an earlier guide to tender. Short on time here to detail, but I suggest readers download the report, enable a file search, and enter "transmission". It makes for fascinating reading. Also, great emphasis is given to "Dynamic Braking"....which is an excellent way to slow a train smoothly and keep mechanical brakes cooler...but that's at odds with the "regenerative" claims!
Here's the only reference I can find to "regenerat" (or)(ive)(ion)(ed)
A token amount. (Edit: To clarify, the UPX model uses a fraction of this for hotel power, but not for tractive effort) Ostensibly most is still dumped as heat. Now I'm starting to understand why the UK DEMU equiv class can reach the same top speed or higher with the same prime motor. You'd expect the insertion loss of the generator/electric traction motor circuit to render a lower top speed and acceleration rate compared to a direct-drive mechanical one....except this vehicle isn't recovering the energy claimed. (See: https://en.wikipedia.org/wiki/British_Rail_Class_220 )
In all fairness, this is still a proposal to tender, but look at how this *could have been done*:
That's DEMU, and state of the art and could almost completely recover braking energy. It would also have lent itself *far more* to line electrification later with mostly just a traction transformer and associated control circuits added, not to mention more controlled grip on slippery/icy tracks and independent traction control.
I'll pore over this report later. Any more where this came from Vegeta? What an eye-opener.
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k10ery
Senior Member
At $150 million a year from taxis and parking I'd say it's a large fortune not a small fortune.
And people wonder why GTAA doesn't do a better job advertising the UPE!
narduch
Senior Member
They've improved the signage immensely, at least at Terminal 1.
smallspy
Senior Member
There is no regenerative braking, because to be regenerative the forces being produced by the wheels braking need to be stored somewhere. And without batteries, catenary or a flywheel, there is no way to store those braking forces created on the DMUs.
The transmission on the DMUs has a retarder - a driveline brake - that provides some measure of braking without using the main disc brakes.
Dan
Toronto, Ont.
mdrejhon
Senior Member
Or sending the same power to a resistor array, and a way to cool down the resistor. (Though I think that's called "dynamic braking" rather than "regenerative braking" -- but laypeople often mix things up)
For readers, some trains, especially elsewhere in the world, redirect excess electricity to dissipate it instead of storing it (from braking via traction motors capable of generating electricity, where many normally call it regenerative braking). This is the heating-up a massive resistor that's on the top, cooled down by the passing air. This can reduce wear and tear on traditional brakes.
So it can be a relatively minor twist that turns "dynamic braking" into "regenerative braking" but it is just braking forces converted to electricity, and what the train does with the electricity, and I understand some trains are able to do both (storing/returning vs dissipating, or theoretically even a split, e.g. a battery becomes too fully charged, a power grid is full of excess power, etc) (My exact terminologies may be wrong)
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