Daimler delivers largest Asian Citaro order to date (Part 3)
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Registered on (6 April 2015, Monday):
SBS6862R
SBS6863M
SBS6864K
Registered on (7 April 2015, Tuesday):
SBS6865H
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SBS6547B
(BBDEP) - on 272 today -
6427P rim guards removed
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Just now pass by pandan C&C, saw unknown citaro with BSEP sticker with engine cover opened & being hoisted up
hmm, more & more citaros need exhausive repairs?
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6864 on sv32 on friday
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Workshops alone tons of Citaros being diagnosed and repair,Particularly to the suspension systems and some complain of powerless accelerations..Haizz
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The older citaros their air suspension always have the click clock noise made when adjusting the angle and level of the bus.
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cannot tahan the weather here. maybe sbst should custom build the bus like DD. or sbst should go for volvo bus with kub body no need any demo bus just build and use
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Think more to the set up of the buses..With the integrated aircon system with the engine power plus SBST traditional way of restricting the accelerate power i am sure the buses is too sensitive for our climate.
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Originally posted by carbikebus:
Workshops alone tons of Citaros being diagnosed and repair,Particularly to the suspension systems and some complain of powerless accelerations..Haizz
Doesn't this have to do with SBST (and to a certain extent, SMRT) locking the first 2 gears of the Citaros to prevent them from over-accelerating and over-spooling the turbo unnecessarily?
If they reverted back to the original mapping, wouldn't there be less BCs complaining of poor pick-up speeds? Since the revs can build up higher before being cut off by the limiter..
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Factory turbo less chances of lagging let alone spool..Its the acceleration they want not top speed.
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6862 seen on 16 for more than a week
6863 seen on 32 for 4 days
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Originally posted by SBS 9631X:
Doesn't this have to do with SBST (and to a certain extent, SMRT) locking the first 2 gears of the Citaros to prevent them from over-accelerating and over-spooling the turbo unnecessarily?
If they reverted back to the original mapping, wouldn't there be less BCs complaining of poor pick-up speeds? Since the revs can build up higher before being cut off by the limiter..
there are several ways to limit vehicle acceleration:
1) engine rev cut-off (i.e. engines cannot rev above a given rpm, i.e. 1500rpm) in certain gears
2) torque limitation through manipulation of fuel injection and turbocharger boost pressures in certain gears
3) across-the-board engine detuning (i.e. overall torque limitation irregardless of gear)i suspect the issue lies more with (3) rather than (1) or (2) because across-the-board detuning serves to reduce fuel consumption more effectively than temporary limiting torque.
for operators with a fuel bill burden, the best strategy would be to reduce overall fuel consumption of the engine irregardless of accceeration/cruising, and that can only be done by detuning the maximum output permissible by the engine.
such across-the-board detuning creates several issues,
1) you lack the torque much needed for quick acceleration, and the Citaro doesnt have that much (1120Nm) to start with.
2) driver safety is compromised when judgement is impaired by sub-par vehicle acceleration and manuverability from bus-stops.
3) if SCR after-treatment is also disabled, expect emission standards to fall below E5.
4) fuel economy is hampered because turbocharger boost pressures are reduced to reduce combustion (and thereby power generated), therefore you are not getting the most out every drop of fuelrev-limiting doesnt limit the acceleration, but the maximum speed possible in the given gear. that will create another danger when power/torque only possibly attained at a given speed is required but not delivered. again, it compromises the BC's ability to maneuver out of bus stops under tricky conditions when the BC may require a higher than usual-speed along with power/torque.
that said, the OM906hLA cut off at about 2200rpm or slightly higher, because 2200rpm is the red-line for the engine. 2000rpm and above is, supposedly, more than sufficient for any BC to move off from a bus stop!
also, turbochargers cannot be over-spooled as a waste-gate diverts exhaust gases away from the turbine once maximum boost pressure is achieved! like it or not, over-acceleration is very unlikely to be an issue on the Citaro given its engine output, transmission design and potential across-board engine detuning.
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Originally posted by SexyMichael:
there are several ways to limit vehicle acceleration:
1) engine rev cut-off (i.e. engines cannot rev above a given rpm, i.e. 1500rpm) in certain gears
2) torque limitation through manipulation of fuel injection and turbocharger boost pressures in certain gears
3) across-the-board engine detuning (i.e. overall torque limitation irregardless of gear)i suspect the issue lies more with (3) rather than (1) or (2) because across-the-board detuning serves to reduce fuel consumption more effectively than temporary limiting torque.
for operators with a fuel bill burden, the best strategy would be to reduce overall fuel consumption of the engine irregardless of accceeration/cruising, and that can only be done by detuning the maximum output permissible by the engine.
such across-the-board detuning creates several issues,
1) you lack the torque much needed for quick acceleration, and the Citaro doesnt have that much (1120Nm) to start with.
2) driver safety is compromised when judgement is impaired by sub-par vehicle acceleration and manuverability from bus-stops.
3) if SCR after-treatment is also disabled, expect emission standards to fall below E5.
4) fuel economy is hampered because turbocharger boost pressures are reduced to reduce combustion (and thereby power generated), therefore you are not getting the most out every drop of fuelrev-limiting doesnt limit the acceleration, but the maximum speed possible in the given gear. that will create another danger when power/torque only possibly attained at a given speed is required but not delivered. again, it compromises the BC's ability to maneuver out of bus stops under tricky conditions when the BC may require a higher than usual-speed along with power/torque.
that said, the OM906hLA cut off at about 2200rpm or slightly higher, because 2200rpm is the red-line for the engine. 2000rpm and above is, supposedly, more than sufficient for any BC to move off from a bus stop!
also, turbochargers cannot be over-spooled as a waste-gate diverts exhaust gases away from the turbine once maximum boost pressure is achieved! like it or not, over-acceleration is very unlikely to be an issue on the Citaro given its engine output, transmission design and potential across-board engine detuning.
Wow, that's a very comprehensive set of info there, many thanks for clarifying.
So, I suppose that since you pointed out that it's likely across-the-board engine detuning for the Ctiaros, so you're guessing too that the Citaros are using too much fuel than what is needed?
I had always thought that they wanted to limit the damage the extra revs in the first 2-3 gears would cause to the turbochargers in the long-run if the gears were allowed to "slip" still from the initial days till now. Do you think this is possible to happen too?
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Originally posted by SBS 9631X:
Wow, that's a very comprehensive set of info there, many thanks for clarifying.
So, I suppose that since you pointed out that it's likely across-the-board engine detuning for the Ctiaros, so you're guessing too that the Citaros are using too much fuel than what is needed?
I had always thought that they wanted to limit the damage the extra revs in the first 2-3 gears would cause to the turbochargers in the long-run if the gears were allowed to "slip" still from the initial days till now. Do you think this is possible to happen too?
any (rational) transport operator would want to reduce their fuel bill, hence detuning is almost certainly the way to go for all vehicles across the board. maybe the citaros are using more fuel than what is needed, especially if the engines are consistently pushed past 1600rpm during acceleration and cruising.
on that note, the Citaro's OM906hLA engine is actually designed for minimal fuel consumption as long as the revs are kept to within 1500rpm. based on how the SBST Citaros are configured (transmission and rear axle differential-wise), as well as how local BCs want that acceleration, its not too surprising that the Citaros are burning more fuel than supposed as a result.
onto the turbochargers, i have a weird feeling that the OM906hLA's turbochargers arent really sounding right. as you have mentioned, immense revving leads to a weird hum in the turbochargers which leads me to suspect that something is loose or worn out in the turbos. assuming that the turbos are working as they should, the wastegate should prevent the turbo from 'overspooling' and hence cause wear and tear; if that assumption holds then the turbos are already worn as suggested earlier and that hard revving merely shows the wear.
i dont quite understand what you mean by 'slipping gears'. in the case of the Voith DIWA, the 1st gear is to some extent a 'slipping gear' where acceleration is derived as the clutch to the mechanical gear closes with the TC (torque converter) providing additional take-off torque. the 2nd gear onwards in the DIWA are fully mechanical gears where slipping does not occur. the engine exhaust directly affects the turbocharger spool, and the transmission is remotely, if not related at all.
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SBST should just have use normal aspirated 4 cylinders engine with no 1-2 gear restriction but still kept within the 60kmh limit then..A world of difference compared to SMRT Citaros..
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soon u can see a citaro burning on the road
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Originally posted by wsy1234:
soon u can see a citaro burning on the road
Less chance...Only more breakdown is a yes...
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Registered on (23 April 2015, Thursday):
SBS6866E
SBS6869Y
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Originally posted by carbikebus:
SBST should just have use normal aspirated 4 cylinders engine with no 1-2 gear restriction but still kept within the 60kmh limit then..A world of difference compared to SMRT Citaros..
are you suggesting that cars (instead of Citaros) that are limited to 60km/h should be used?
P.S.: they fit the description quite well!
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Volvo B5 also 4 cylinders,New MB OM934 also 4 cylinders
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wah bro, liddat also can ar?
one question ar, are the engines u mentioned (D5F/D5K, OM934LA) turbocharged?
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Registered on (28 April 2015, Tuesday):
SBS6867C
SBS6868A
SBS6870S
SBS6871P
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30 extra Citaros have been registered...the only way to determine whether they are part of Batch 3 (some people just don't believe that deliveries can be pushed forward) is when it reaches 250 in total...
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Originally posted by SexyMichael:
there are several ways to limit vehicle acceleration:
3) across-the-board engine detuning (i.e. overall torque limitation irregardless of gear)Irregardless? That means that the overall torque limitation does depend on the gear.