Scania K230UB acceleration

last SG · 2008-12-02T17:01:11+00:00

even the B10M MKIIs used ZF4HP500. Actually can someone explain to me why the MKII's ZF sounds different from all the other ZFs?

JaSoNhSu92 SG

B9TL got the "ding ding" sound when the bus is moving at higher speed, issit the speed limiter made that sound?

bus555 SG

the ding ding is when the bus hits 50km or more!

n4l SG

haha, the thingy spoil liao or isit BC go set here and there?

Both also possible mah... (:

SBS8033D SG

B9TL got the "ding ding" sound when the bus is moving at higher speed, issit the speed limiter made that sound?

ding dong ding dong, that sound sounds nice after all, but has a reason coz of the limiter. Buses at most can go 60 km/h, but if you see go speeding from the gauges, then you may be wrong.Always hear it when onboard 161 at SLE/TPE.

Powered_By_CNG SG

The Scania DC9 engine has a very wide band of engine speeds where maximum torque is available. Maximum torque of the base-model (DC9 16 230 Euro 4) engine is 1050Nm @ 1100-1500rpm. The engine runs optimally at engine speeds between 1100rpm and 1700rpm although quite often the maximum engine speed is limited by transmission settings.

In contrast, the engines in the Volvo B10Ms have a very narrow band of engine speeds where maximum torque is available. The THD102KF has 1050Nm (same as the DC9 16 230) but maximum torque is available only at 1400rpm. The torque curve drops substantially below and above 1400rpm. In order to obtain the best acceleration from the THD102KF, the driver needs to use the power of the engine and allow engine revs to remain high.

In my opinion, the best city bus engine has 6 cylinders, (a) variable geometry turbocharger(s), displacement of between 10 and 12-litres, a power rating of between 185kW and 240kW available at as low as possible engine speed, and 1100Nm or greater torque available between 1000-1400rpm or wider. The engine should be hooked to a 5-speed ZF transmission with a high-speed diff. The top speed should be electronically limited.

Regards,
Dave

nenepokey SG

Regards,
Dave

Mercedes-Benz OM457HLA coupled with ZF6HP592C is the best!

Powered_By_CNG SG

The OM 457 hLA (as well as the previous OM 447 hLA) is quite a good engine. The 220kW version used on SMRT's OC 500 LEs develops a whopping 1000Nm already at 600rpm (idle speed) and over 1100Nm by 800rpm. Mercedes-Benz diesel engine have traditionally featured very flat torque curves for the best driveability.

Regards,
Dave

chickenlittle2 SG

for free tickets???

Siao la.. Fast also want to complain, slow also want to complain. I muz say some Singaporean had nth better to do.

SBS n SMRT SG

Siao la.. Fast also want to complain, slow also want to complain. I muz say some Singaporean had nth better to do.

They should know BC had a schedule to adhere to

lianamaster SG

So do most buses have their speed limits electronically controlled?

SBS n SMRT SG

So do most buses have their speed limits electronically controlled?

yah.....speed limitator caps speed at 60kph

lianamaster SG

yah.....speed limitator caps speed at 60kph

Oic....

Raraken SG

Regards,
Dave

So is that why MB buses can take-off from the bus-stop with a full load fast?

Seen O405s with OM447hLA engines around the mountainous regions of Germany alot.

Powered_By_CNG SG

So is that why MB buses can take-off from the bus-stop with a full load fast?

Yes. The OM 447 hLA and OM 457 hLA engines have high torque output even at engine speeds close to idle. High torque (pulling power) is critical for acceleration with a full bus load of passengers.

Regards,
Dave

SBS9888Y SG

LTA requires all buses to be capped at 60kph. In fact, i notice many BN buses are going above 60.

SBS n SMRT SG

LTA requires all buses to be capped at 60kph. In fact, i notice many BN buses are going above 60.

They alter speed limitator

BB2001 SG

Regards,
Dave

Thanks for your reply, Dave.

I did not take note of the current B10M torque band when I was with SBS. Are you referring to the THD101GC instead? Because I do experience pretty good acceleration from 1200 rpm for the THD102KF. In fact many drivers hardly drive at higher revs, unless overtaking or overcoming steep slopes with heavy loads, or just to have some fun.

The THD101GC engine of earlier B10M indeed require reving due to narrower power bands.

According to the Scania website, the K230UB maximum power is attained at 1800rpm, which means that the ZF gearbox should upshift at 1800rpm at maximum acceleration. I think I can safely assume that the acceleration for the K230UB should be better than the B10M at narrower gear ratios and same torque ratings.

I agree with you that city driving, power band should be wide. It makes driving more pleasurable.

So the only thing that can get in the way of better acceleration is the unladen weight. Do you agree?

BB2001 SG

Regards,
Dave

At 220KW, it should be one of the most powerful engine to be used in a rigid single decker city bus, especially in SG roads. Wonder why the use of such a powerful engine.

Usually high powered engines are used for long distance overland travelling whereby buses hit around 100km/h to 140km/h.

I assume the unladen weight of the OC500LE is around 11 ton. Coupled the engine with the ZF gearbox, I believe the acceleration can be quite blistering.

BB2001 SG

Regards,
Dave

At 220KW, it should be the most powerful engine to be used in a rigid single decker city bus, especially in SG roads. Wonder why the use of such a powerful engine.

Usually high powered engines are used for long distance overland travelling whereby buses hit around 100km/h to 140km/h.

I assume the unladen weight of the OC500LE is around 11 ton. Coupled the engine with the ZF gearbox, I believe the acceleration can be quite blistering.

Powered_By_CNG SG

I have found that the THD102KF isn't as good as previous generations. The THD100D (used on Volvo B58s, B59s and early model B10Ms) was the best.

In normal everyday traffic, how often does one push a bus engine to 1,800rpm? The answer is generally rarely ever unless the transmission is ill-suited to the task at hand. An engine with high torque at low engine speeds as well as a suitable transmission with suitable programming are therefore required for good in-traffic acceleration characteristics. In order to calculate the optimal up-shifting engine speed, it is necessary to investigate passenger comfort levels (read: shifting comfort) as well as specific fuel consumption of the engine at various speeds. Up-shifting at 1,800rpm is unnecessary - operating an engine at or above it's 'rated' speed (yellow to red on the tachograph) results in high fuel consumption and unnecessary engine wear. It is therefore wise to ensure that the engine operates within its 'green zone' as much as possible. At the same time, it is also unwise to operate an engine at speeds below the 'green zone', as again fuel economy, performance, engine life and smoothness suffers. Allowing an engine to run below the 'green zone' also promotes 'hunting' - where the transmission is constantly 'between gears' - resulting in poor passenger comfort levels.

In order to understand why new buses may not perform the same as older buses, it is necessary to understand the concept of torque reduction. Many new engines are fitted with OBD (On-Board Diagnostics) systems that monitor the health of the engine as well as the exhaust output. In order to guarantee low emissions levels, some engines are 'cut back' at low speeds under full load. If the OBD system detects an engine fault, the torque output of the engine is also reduced. From experience, newer buses require more frequent servicing to ensure reliable operation.

Remember, official engine power and torque figures are measured under ideal circumstances.

So the only thing that can get in the way of better acceleration is the unladen weight. Do you agree?

As above, there are more variables than you think. Modern buses, with all their creature comforts, safety and emissions control gear will almost always be significantly heavier than previous generations of buses.

Regards,
Dave

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