SMRT Yutong bus - A discussion on China buses

TIB1224Y SG

On the contrary Japanese diesel engines are designed to be of low power and low consumption.

That is why the PE6H is only 230PS... But not to worry, they have single deck coaches (JDM) that feature 450PS engines, much powerful to compare with a European coach...

Raraken SG

Why didn't they put a 4-speeder transmission inside the KUBs? Svc 66 KUB got pwned by svc 178 UD.

I know a 6-speeder is more economical in greener, but, why?

carbikebus SG

6 speed auto gear tend to less stress than 4 speed one,Less dragging better fuel effiency.Only stress if gearbox fail

Oceane SG

6 speed auto gear tend to less stress than 4 speed one,Less dragging better fuel effiency.Only stress if gearbox fail

But alot of 6-speed start to whine "Noo don't stress me~"

Then the whole bus goes "Ooooorh oooooorh"

SGCar SG

But alot of 6-speed start to whine "Noo don't stress me~"

Then the whole bus goes "Ooooorh oooooorh"

Cheers.

TIB537B SG

But alot of 6-speed start to whine "Noo don't stress me~"

Then the whole bus goes "Ooooorh oooooorh"

seems like the ZF4HP500 still pawns all gearbox in Singapore

carbikebus SG

If u really understand what's the purpose of 6 speed gear then you'll understand why SBST fit into their new buses and not 4 speed ones.

Raraken SG

seems like the ZF4HP500 still pawns all gearbox in Singapore

Definitely. The gear can drag a lot, even gives better acceleration. Plus, on some buses I have taken, the 4-speeders will shift like 6-speeders, very fast.

@CBB: Yes I know why, for Better Fuel Economy, for greener emmisions, for better or for worse etc. , but they will never beat the mighty ZF4HP500!

TIB1224Y SG

4 speed ZF also out of regular production liao, want must scavenge from other buses lols...

By putting an example, upon a velocity range of 0 to 60 km/h, a 6-speed can afford to change gear at 1400-1500 RPM nominal, cruise at 60 km/h at 1300 or less RPM. Whereas a 4-speed changes gears at about the same range, but cruise at 60 km/h at 1800 RPM nominal, causing greater fuel burn gradualy, if constantly cruising at the same speed.

For a Voith 3-speed, it would be slightly worse, in this case taking an articulated bus as example, gear change from 1st to 2nd occurs about 1900-2000 RPM, 2nd to 3rd, contributed by the DIWA series its lowered to 1500-1600 RPM for a gear change, but cruising at 60 km/h is about 2100 RPM, between the range of green and orange on the tachometer!

Gearbox speeds are about gear ratios, the more tightly packed your gear ratios, the more times u have to change gears and the lesser RPM travel u will have for each gear. However, according to a technical report, it also causes more wear on the clutch plates, by constantly changing gears, your engine will also be stressed.

A ZF 6-speed (6HP592C, CAN bus capable) has gear ratios of, from 1st the 6th, 3.43, 2.01, 1.42, 1.00, 0.83, 0.59, while a Voith 3-speed (DIWA 863.3E, enhanced version) features gear ratios of, from 1st to 3rd, 5.90 (for DIWA versions) (5.1-5.4 for differential 4), 1.43 (1.36 for differential 4), 1.00.

The larger the gear ratio, theoratically, you can have higher traction and lesser speed, that is why its said that Voith 3-speeds can easily climb gradients. This would also have to be dependant on your vehicle's axle differential and ratios and actual engine power, engine conditions and operating conditions etc...

16/f/lonely SG

The Voith 3 speed is quite disadvantaged.

Look at the wide gap in size between the first and second. The engine would need to push to high rpm before it is ok for the momentum to be carried over to the 2nd gear.

And given that lock-up occurs as it transits from 1st to 2nd at this high rpm......more stress on the engine and the clutch.

SBS7322B SG

The Voith 3 speed is quite disadvantaged.

Look at the wide gap in size between the first and second. The engine would need to push to high rpm before it is ok for the momentum to be carried over to the 2nd gear.

And given that lock-up occurs as it transits from 1st to 2nd at this high rpm......more stress on the engine and the clutch.

Explains the slower pick up than ZF gearboxes.

carbikebus SG

ZF is not slow mind you,Its the tuning and lastly the driver itself.Some bigger cars like the Rolls Royce has been using ZF gearbox eons ago.I agree that Voith gearbox climb hill better.The only best Voith gearbox i can recall is the 4 speed ones.Based on my past experiences becoming SBST BC and SMRT SL i still prefer to drive ZF equipped gearbox buses.

sBs_boy SG

But seems to me that somebody can chiong better with a Voith machine..

carbikebus SG

I shall not say further..Only driving experience know it all.May be true Voith accelerate slightly better on standstill but mid range and long range ZF much better.

Raraken SG

But seems to me that somebody can chiong better with a Voith machine..

It seems they all do. On some Mk IIIs, same rev (1800 rpm) and they go faster than a lot of SMRT Merz on 961 and 178 along Woodlands Road. Even SMRT Bendies with Voith speed alot faster than ZF, like on 856. All are revving in the red zone, but the Voith Bendies are always a wee bit faster.

TIB1224Y SG

What I observed on 1224...

When the speed closes to 60 km/h, there is a rapid increase or RPM over the range from 2000 to 2200 RPM, the maximum governed speed the engine can run at, according to the tachometer. The 2000 to 2200 RPM comes about 55 to 60 km/h, when the RPM would increase to the maximum that the engine can be told to run. Not sure if this occurs to other Voiths as well.

TIB930Z SG

Voith : Climb hill (GOOD)

ZF : Pick-up , acceleration (GOOD)

what's the point of haviing a high RPM but pick-up, gear change is slow ?

while ZF dosen't have much RPM as voith have but performs better than voith ? Singaporeans rush here rush there de, Voith is so not suitable on public transport in Singapore . Other Country Voith maybe can , one more thing Voith is smoother , Zf is kinda of jerky , you prefer save time or comfortable ?

SMRT BUSES LuvER SG

Hmm.. Which gearbox do u guys think tht will be installed on the Yutong?

Pls vote!

TIB537B SG

Hmm.. Which gearbox do u guys think tht will be installed on the Yutong?

Pls vote!

ZF 6 ba, or Voith. Allison unlikely.

TIB958U SG

Hmm.. Which gearbox do u guys think tht will be installed on the Yutong?

Pls vote!

If I'm not wrong, ZF4HP500 should be out of factory production now.

« Previous Page Next Page »