#4000 Arrives

[sw4400]

A friend got this in her email

The 4000's cannot fit under the Wilson and Ravenswood viaduct?

I borrowed some pics from Kevin's "Photos" section for comparison study... do the 4000's roof pods really look larger than the 7500's HVAC pods and thus cannot fit under that viaduct at Wilson and Ravenswood?

4008.bmp

7534.bmp

[ryanbytes]

Here's a sticker from a later 4000.

[jajuan]

Here's a sticker from a later 4000.

http://farm4.static.flickr.com/3300/331027...c18ce1712_b.jpg

If I rememeber correctly the sign giving the viaduct's height says it's 10'6", so that makes the 4000s 3" too tall.

[wordguy]

If I rememeber correctly the sign giving the viaduct's height says it's 10'6", so that makes the 4000s 3" too tall.

Your memory is accurate, Jajuan. 10'6" is the clearance.

I guess the roof pod theory seems to pan out. So, unless some of the NABIs return to service, that route change could become permanent --- unless a short section of Wilson is rebuilt, lowering the level of the pavement under the RR overpass. Probably not very likely to happen any time soon, if ever, stimulus or not.

[Chicago13]

Your memory is accurate, Jajuan. 10'6" is the clearance.

I guess the roof pod theory seems to pan out. So, unless some of the NABIs return to service, that route change could become permanent --- unless a short section of Wilson is rebuilt, lowering the level of the pavement under the RR overpass. Probably not very likely to happen any time soon, if ever, stimulus or not.

Having just checked the CDOT website, I don't understand why they just didn't reroute via Montrose to Damen to Lawrence. according to the PDF posted there, the clearance at Montrose/Ravenswood is 13'8" and Lawrence/Ravenswood is 14'4".

That way they could still use 4000's to serve Damen/Brown Line with no problem.

[ryanbytes]

Having just checked the CDOT website, I don't understand why they just didn't reroute via Montrose to Damen to Lawrence. according to the PDF posted there, the clearance at Montrose/Ravenswood is 13'8" and Lawrence/Ravenswood is 14'4".

That way they could still use 4000's to serve Damen/Brown Line with no problem.

If it runs down Montrose to Damen it runs right past the Montrose Brown line stop which makes the trip to the Damen Brown line stop unneeded.

[Chicago13]

If it runs down Montrose to Damen it runs right past the Montrose Brown line stop which makes the trip to the Damen Brown line stop unneeded.

Even still, why cut off service to the Brown Line, when it would have been just as easy to maintain it by simply rerouting to Montrose from Wilson?

[ArcherRider]

I saw NF #4098 on #146 yesterday.

[jajuan]

Even still, why cut off service to the Brown Line, when it would have been just as easy to maintain it by simply rerouting to Montrose from Wilson?

I'm guessing management wanted to go with the less complicated loop between your proposal and what they chose to go with.

[Busjack]

Also, the route was originally to Wilson-Ravenswood, and that part seems intact.

The new map has the Ravenswood Metra station as a point of interest, but I really doubt that is a point that will generate much ridership either. If you want to go to Damen/Brown Line, people generally take the Brown Line.

[Busjack]

To put this in a better thread:

Yes. The 4000s have a continuously variable transmission that keeps the engine revving at exactly the speed it needs to depending on load, so like your friend's Prius, its revs rise and fall so slowly, it's virtually impreceptible.

Unlike the Prius, however, the 4000s are no quieter than anything else in the rear section of the bus. The engine doesn't shut down when not needed like it does in the Prius, and between the VERY loud final drive gear whine and cooling fans that spool up loudly during high-speed brake regeneration, there's quite a racket going on back there.

The prius' quietness is not necessarily due to it's being a hybrid, but rather, a different set of design criteria than a hybrid city bus. 1) Because the Prius starts and stops its engine periodically, the engine (and generator motor/starter) must be quiet and isolated enough that it's not bothersome. As a result, the overall drivetrain operation is VERY quiet indeed, even when the gas engine is running. 2) Whisper quiet operation was likely a deliberate design criteria overall because Toyota needed to demonstrate to buyers a tangible "benefit" to "greener" driving.

You are inconsistent in saying that the 4000s have a CVT and then that it gets into final drive.

Having ridden some, it doesn't sound like a CVT, just like the engine is sometimes not engaged in first gear, but then comes on and shifts into higher ones.

The GM system is not the same as on a Prius (the Prius one is designed to optimize running only on electric power), and if it is even similar to the one in GM SUVs, the advertisements for them say that while in second mode they can use their gears like they were in a CVT, it is not a CVT, in the sense of a variable belt transmission. (The buses and CVT seem to have the same system. The bus brochure is here, if any of you can figure it out, while the two mode SUV description is here. The specifications for the Yukon hybrid say that it has a 4 speed transmission with overdrive.)

Also, you seem to be confused by saying that the bus "engine doesn't shut down when not needed like it does in the Prius," in which case it wouldn't save fuel. It might if it ran in constant speed mode, but only the series hybrids do that, and the GM system is not a series hybrid. Again, the literature seems to indicate that the engine runs in constant speed mode only when it gets to speed (such as the infinite drive making small adjustments while cruising on LSD).

Also, the noise generated by the HVAC in back tends to mask what the engine is doing.

[santran]

4102 and 4005 are on NP property. Looks like NP is getting both odds and evens for the moment. And they need them the 135's are way too crowded.

[speedracer1407]

To put this in a better thread:

1) You are inconsistent in saying that the 4000s have a CVT and then that it gets into final drive.

2) Having ridden some, it doesn't sound like a CVT, just like the engine is sometimes not engaged in first gear, but then comes on and shifts into higher ones.

3) The GM system is not the same as on a Prius (the Prius one is designed to optimize running only on electric power), and if it is even similar to the one in GM SUVs, the advertisements for them say that while in second mode they can use their gears like they were in a CVT, it is not a CVT, in the sense of a variable belt transmission. (The buses and CVT seem to have the same system. The bus brochure is here, if any of you can figure it out, while the two mode SUV description is here. The specifications for the Yukon hybrid say that it has a 4 speed transmission with overdrive.)

4) Also, you seem to be confused by saying that the bus "engine doesn't shut down when not needed like it does in the Prius," in which case it wouldn't save fuel. It might if it ran in constant speed mode, but only the series hybrids do that, and the GM system is not a series hybrid. Again, the literature seems to indicate that the engine runs in constant speed mode only when it gets to speed (such as the infinite drive making small adjustments while cruising on LSD).

5) Also, the noise generated by the HVAC in back tends to mask what the engine is doing.

I wanted to respond to each point of your post individually, but that feature is unavailable on this forum. So I'll respond to each paragraph sequentially. I added numbers to your quoted response for ease of reference

1) "Final Drive" is not a gear inside the transmission, but rather, the final drive ratio, or the final gear reduction inside the differential. All cars, trucks, buses, etc have a final drive, though the term may vary in different transportation engineering vernaculars. #4000s on the 147 emit a pronounced gear wine that grows very loud and increases in pitch at high speed on LSD. I assume this is from a strait-cut gear component inside the differential because the pitch of the whine is directly proportional to the speed of the bus. For what it's worth, this gear whine is exactly the same on the #1000s, likely because they share a similar differential, and it too is proportional to speed rather than engine RPM.

2) I find the them to sound very much like a CVT in that the engine note (which as you point out below is indeed difficult to hear at times) rises and falls completely irrespective of vehicle speed. Rather, the engine revs up and down (rather slowly) depending on load, and in most situations, maintains a relatively constant RPM, even when accelerating.

3) Right. But I suppose it depends on how you define CVT. A "conventional" CVT, as found in the Prius, does indeed use a variable belt transmission. But the Allison transmission uses the two electric motors and clutch packs, along with the more "conventional" planetary gear sets of a standard automatic transmission to create continuouse and infinite gear ratios. Thus, I was using the term CVT because it is indeed a transmission that can continuously vary its ratios.

4) I'm a little unclear about what you mean by "in which case it wouldn't save fuel." As you noted, both the Prius and the hybrid bus are parallel hybrids, and in theory, both can operate on electric power, gas/diesel power, or both. All parallel hybrid cars shut down the gas engine when the computer decides it isn't needed, such as when accelerating slowly from a stop, coasting, decelerating, etc. in an effort to save fuel. After a few hundred miles seat time driving my friend's Prius, I came away surprised at just how often the computer shut down and restarted the engine. Sometimes, it would go on and off 4 or 5 times in a minute while cruising around town at a constant speed. In the #4000s, however, the diesel engine is always running, even when stationary. While shutting off the engine may save fuel by allowing the electric motors to keep systems running and creep the bus forward in heavy traffic, I'm willing to bet that starting and stopping an 8.9L diesel engine hundreds of times a day presents added complexity and potential reliability problems on a bus designed for 12+ years and hundreds of thousands of miles of hard use.

5) Agreed. I had a hard time figuring out what the engine was doing at first. But after riding the #4000s day in and day out for a while now, I've been getting better at distinguishing various engine compartment and HVAC noises from actual engine noise. And since the HVAC lives on the roof of the 4000s, it's a bit less intrusive in back than on the 1000s.

BTW, here's a highly technical paper on various hybrid systems, including the GM/Allison. When it gets into formulas, it's way over my head.

http://www.engin.umd.umich.edu/vi/w4_works.../Miller_W04.pdf

[jacksone44]

4102 and 4005 are on NP property. Looks like NP is getting both odds and evens for the moment. And they need them the 135's are way too crowded.

you mean 4105?

[BusHunter]

you mean 4105?

#4005 is on the #156 this morning. The evens are starting to show up though. #4098 was on the #152 as a NP school run yesterday.

[cta 5555]

Last night i saw 4104 going east on foster and pulaski at 1846.

[Jon]

4101 did a school run for Lane Tech this afternoon. Ended up at the Addison Ravenswood around 1515. I could've sworn the runbox said K525, but that wouldn't make a whole lot of sense to send a Kedzie bus to Western considering North Park is closer. Anyone else see 4101 this afternoon on Western and can confirm/deny what the runbox showed?

[Busjack]

I suppose we'll know when and if 4207 is seen.

Now the press reports say that Mayor Daley's office says 52 hybrid buses from the stimulus plan. Sure have to love the transparency.

Tribune

Sun-Times

[wordguy]

Now the press reports say that Mayor Daley's office says 52 hybrid buses from the stimulus plan. Sure have to love the transparency.

Tribune

Sun-Times

52 hybrid buses for $52 million? $1 million each? Seems a little high, doesn't it?

[trainman8119]

52 hybrid buses for $52 million? $1 million each? Seems a little high, doesn't it?

Well, CTA is paying a buck and a half more for fuel than it really needs to now, so

whose to say that overpaying for a bus is out of line. Maybe it would just be smarter

to buy standard 40 foot buses and get a few more for the money. But then, when has

anyone in this town done anything smart in the past few years ???

[Busjack]

52 hybrid buses for $52 million? $1 million each? Seems a little high, doesn't it?

In Nov. 2007, the lease was for $800K each, which was supposed to be a deal over the rate of inflation built into Seattle's contract, which was $860K (according to a press release). I wouldn't be surprised at $1 million, but we don't know if that is from the 58 options or the RFP for 900 more. Sounds a bit high for the options. It is a given that a hybrid is at least $200,000 more than a regular bus.

However, it is a lot more than the $480,000 each paid in 2003 for the "Top of the Line, 60-foot Buses" which a press release says " 'With these new buses, express trips between outlying neighborhoods and downtown will be more enjoyable and dependable in any time of year,' Mayor Daley said at a news conference at the CTA bus garage at 1702 E. 103rd St." Now, after five years, they are written off here as pieces of garbage.

Also, the budget amendment approved by CMAP was $55 million.

The moral may be that a certain Mare should keep his hands and mouth off the CTA (or at least his press office should).

You also get my point about transparency.

[BusHunter]

4101 did a school run for Lane Tech this afternoon. Ended up at the Addison Ravenswood around 1515. I could've sworn the runbox said K525, but that wouldn't make a whole lot of sense to send a Kedzie bus to Western considering North Park is closer. Anyone else see 4101 this afternoon on Western and can confirm/deny what the runbox showed?

Np sends out those school runs with the same run numbers. Are you sure you saw a K? BTW, in the uh- oh catagory, I was aboard #4046 and at the articulation point the bus was squealing every time it made a turn. I remember the NABI's doing this and we know what happened to them.

[Jon]

I didn't get a chance to see it in person, but 4109 did a Lane Tech school run around quarter after 15 today.

Np sends out those school runs with the same run numbers. Are you sure you saw a K?

It very well may not have been; I was already on the platform and caught only a glimpse of the run box. All I'm certain of is that the numbers were '525.'

[jacksone44]

Np sends out those school runs with the same run numbers. Are you sure you saw a K? BTW, in the uh- oh catagory, I was aboard #4046 and at the articulation point the bus was squealing every time it made a turn. I remember the NABI's doing this and we know what happened to them.

I am on a 4000 everyday (sometimes twice a day) and when the bus is jammed packed, the joint starts squealing... maybe the weight load towards the back starts to make it do that? maybe it needs to be oiled ?? no idea....

[jajuan]

Np sends out those school runs with the same run numbers. Are you sure you saw a K? BTW, in the uh- oh catagory, I was aboard #4046 and at the articulation point the bus was squealing every time it made a turn. I remember the NABI's doing this and we know what happened to them.

It could just be from the different surfaces in the joint rubbing across each other. Didn't the articulation joint in the 7100s and 7300s make a noise whenever one of those made a turn?