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7900-series Nova LFS - Updates


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1 hour ago, CTA5750 said:

I know Pace buses had them. You could switch it on or off depending on the road conditions. Our city firetrucks also have them.

What's the purpose of having engine brakes on buses? To prevent overuse of the service brakes due to frequent stopping? When I drove trucks, I was taught they were mostly for preventing acceleration on downgrades, but that doesn't seem applicable to CTA or Pace.

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39 minutes ago, sht6131 said:

I do not understand why these garages keep sending Novas for fill ins. We have no proof that that Kedzie will go Novas. It would make more sense to send Flyers which the Kedzie operators are familiar with.

 

 

It could depend on what's available at a particular given time.   Perhaps when K requested a bus, 74th only had Novas that just came off the street available.   Based on that,  Novas might have been the only spares they had at that time.  It sounds like this could've happened at or near the height of the p.m. rush hour.  Seems like C, which is the closest to K, didn't have any spares.  North Park probably only had artics available,  which means 74th was the next available garage. 

It could be that other garages had spares, but 74th had someone available to drive the bus to K, and a Nova was the next bus in a short line to get out.  Since buses are usually lined up bumper to bumper,  there's no opportunity to cherry pick.  If there are 5 buses in a line, and buses1 and 5 are Novas, why do extra maneuvers to get a New Flyer from the middle of the pack?  Grab the first bus and go.

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2 hours ago, Pace831 said:

What's the purpose of having engine brakes on buses? To prevent overuse of the service brakes due to frequent stopping? When I drove trucks, I was taught they were mostly for preventing acceleration on downgrades, but that doesn't seem applicable to CTA or Pace.

I don't ever recall hearing the retarded on CTA buses.  But the original purpose on trucks and highway coach buses was to prevent drivers from using the service brakes going down steep grades.  The service brakes would get hot and then give out, meaning there would be no way to stop the vehicle.  On long, steep,  downhill grades you will sometimes see "runaway ramps" which are made of gravel.  Those are meant to stop runaway trucks and buses that have lost their brakes.

Secondarily,  engine braking can help on slicker roads where using the service brakes can lead to sliding. 

However,  certain jurisdictions restrict or outlaw engine braking because the retarders can be very loud if put on the max setting.  The only reason I can see them on transit buses is to increase the intervals between brake jobs.  

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36 minutes ago, artthouwill said:

It could depend on what's available at a particular given time.   Perhaps when K requested a bus, 74th only had Novas that just came off the street available.   Based on that,  Novas might have been the only spares they had at that time.  It sounds like this could've happened at or near the height of the p.m. rush hour.  Seems like C, which is the closest to K, didn't have any spares.  North Park probably only had artics available,  which means 74th was the next available garage. 

It could be that other garages had spares, but 74th had someone available to drive the bus to K, and a Nova was the next bus in a short line to get out.  Since buses are usually lined up bumper to bumper,  there's no opportunity to cherry pick.  If there are 5 buses in a line, and buses1 and 5 are Novas, why do extra maneuvers to get a New Flyer from the middle of the pack?  Grab the first bus and go.

That does make sense.The three Novas from 74th happened this morning AM rush. It just seems that since this Nova fill in started, that it was all Novas. Thanks.

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9 minutes ago, artthouwill said:

Secondarily,  engine braking can help on slicker roads where using the service brakes can lead to sliding.

I assume this refers only to rear wheel drive buses, as it would be a bad idea on other vehicles. It still seems debatable though. The engine brake is typically not recommended in slippery conditions because only the drive axles are being slowed, creating disproportionate forces that can cause a skid. ABS is supposed to mitigate the risk of using the service brakes by properly balancing the braking forces.

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7 minutes ago, sht6131 said:

That does make sense.The three Novas from 74th happened this morning AM rush. It just seems that since this Nova fill in started, that it was all Novas. Thanks.

If it was a.m rush, more than likely it was a Niva from the N9 or one of the other owl routes that pull in.  These buses probably serves as spares for the a.m rush.

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8 minutes ago, Pace831 said:

I assume this refers only to rear wheel drive buses, as it would be a bad idea on other vehicles. It still seems debatable though. The engine brake is typically not recommended in slippery conditions because only the drive axles are being slowed, creating disproportionate forces that can cause a skid. ABS is supposed to mitigate the risk of using the service brakes by properly balancing the braking forces.

You are right.  

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1 hour ago, artthouwill said:

It could depend on what's available at a particular given time.   Perhaps when K requested a bus, 74th only had Novas that just came off the street available.   Based on that,  Novas might have been the only spares they had at that time.  It sounds like this could've happened at or near the height of the p.m. rush hour.  Seems like C, which is the closest to K, didn't have any spares.  North Park probably only had artics available,  which means 74th was the next available garage. 

It could be that other garages had spares, but 74th had someone available to drive the bus to K, and a Nova was the next bus in a short line to get out.  Since buses are usually lined up bumper to bumper,  there's no opportunity to cherry pick.  If there are 5 buses in a line, and buses1 and 5 are Novas, why do extra maneuvers to get a New Flyer from the middle of the pack?  Grab the first bus and go.

The real question is what is going on at kedzie with there fleet maintenance, because i've seen a number of there buses in recent weeks popping up more and more at Southshops. I remember a week or so go when we loaned some of our 1100's and 1200's to kedzie while we received a host of 1600's and 1700's from them to either work on or drive as loans.

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On 12/12/2019 at 3:02 PM, Pace831 said:

What's the purpose of having engine brakes on buses? To prevent overuse of the service brakes due to frequent stopping? When I drove trucks, I was taught they were mostly for preventing acceleration on downgrades, but that doesn't seem applicable to CTA or Pace.

I was taught it was to extend brake life. Use of the retarder function would be restricted only to dry pavement. Im taught to not use this function in heavy weather  Still, I dont know why 
Pace buses are equipped. Now Chicago Firetrucks do have them  Good question!!!

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1 hour ago, CTA5750 said:

I was taught it was to extend brake life. Use of the retarder function would be restricted only to dry pavement. Im taught to not use this function in heavy weather  Still, I dont know why 
Pace buses are equipped. Now Chicago Firetrucks do have them  Good question!!!

I rode Pace 6706 on August 18 after this really extreme rainstorm has happened. The bus driver had the retarder on and we went under the Green Line bridge on Harlem Ave. and it was flooded, which is why a detour has happened, but this driver took the normal 307 way. At least the bus didn't break!

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17 minutes ago, Shannon CVPI said:

Quick question since I seen 8222 on the 63 at cottage Grove on my way home after leaving FG didn't it served at C for a short time or did it go straight to 6 after leaving FG I know 8225 went to 6 during the winter pick back in 16

IMG_20191224_204448570.jpg

8222 been at 74th since it left FG you're correct. It was 8224 that was at C for a while then came over to 74th ??. I was at 74th from 2016 to 2018 and I dont remember seeing 8225 there.

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