[MileCruncher]

I'm just back from a quick trip to Delhi and was happy to see maximum percentage of DTC fleet on JNNURM are now low floor and rear engine buses. But did strike both through a ride and the engine sound, the Ashok Leyland buses seem to have less power compared to Marco Polo ones. The engine sound make this more evident.

Has there been any comparison between the two? Somehow I felt Marco Polo's were way ahead of the AL ones in all respects.

[esteem_lover]

I have always felt TATA buses were more quiet and powerful compared to the AL buses, same goes for the lorries too, guess they are the same. Wish one of them would actually start making buses.

Here in Chennai, the latest buses sponsored by JNNURM, the AL buses look more sleek and original compared to the Marcopolos which have disproportionate body length in the front, trying to look like VOLVOs.

[tsk13]

DTC also has 4 White CNG - Electric Hybrid Tata Marcopolo Low Floor buses and apart from this, I've seen one Tata Starbus Low Floor which was brought in as a part of the Pilot Project to test Low Floors in Delhi. Initially, this bus served Route 623 and now is seldom seen owing to large numbers of new generation Marcopolos and AL's.
Link to Hybrid Bus: Tata group | Tata Motors | Media releases | Tata Motors' CNG-electric hybrid bus, India

The recent update is that Private Low Floor Buses, part of the Government initiative to rope in Corporates to run buses have commenced operations. These Orange coloured Marcopolos are seen plying on Route No. 419 and few other routes originating from Ambedkar Nagar.

For AC AL Low Floors, thing such as Wrappers, Polythene bags et al get stuck in the Inlet Provision for AC at the rear. AL suffers from lack of power, which one can understand from the Engine noise as mentioned here. The Tatas have great force, the drivers enjoy clocking above 40 Km/Hr easily inspite of the fact that both makes of these buses are said to have Speed Governors.

Haryana Roadways has Low Floor Volvo City Buses on the route ISBT Kashmere Gate - Ballabgarh. These are the sole Volvos visible amongst Tatas and AL's.

[AkMar]

The CNG AL low floor AC bus which is with BEST is underpowered compared to Marcopolo. I guess the same should be true for DTC also. The depot which holds the bus prefers not to turn it out on road as far as possible.

[julupani]

Though even I think the MarcoPolo RE buses to be better than the ALLs, I didnt think it would be on power. That's because I think,the DTC ALL/TMML buses use the same Cummins CNG engine. In fact the particular engine was in fact mentioned in the tender document itself, forcing everybody to use the same engine. Or am I mistaken here??

[MileCruncher]

Does anybody has the technical specifications for the CNG Buses of both the makes? Will make for easier comparison. If its the same engine then may be gearing is the culprit here.

[julupani]

ALL's website doesn't seem to have a page for their RE LF CNG buses, or at least I cant find it. But you can find the detail tech specs of the Tata RE LF CNG bus here.

Some short specs are: 230hp/680nm engine with an Allison automatic transmission.

[SAE40 in veins]

Both use a Cummins 5.9 liter BG+ CNG unit coupled to an Allison T 270 transmission. Tata Marcopolo buses had certain advantages due to a professional 'Body Building' set up in Dharwad and also dealing with Cummins was a lot easier for Tatas compared to ALL.

[julupani]

I think ALL too have "professional body building" setup in Alwar isnt it. Also, I dont think the quality of bodywork would make the Leyland feel less powerful than the Tata.

Also what do you mean dealing with Cummins would have been lot easier for the Tatas here. I am sure they haggle over the price of the engines contract, but not over who gets how much horsepower.

[MileCruncher]

Originally Posted by julupani

I think ALL too have "professional body building" setup in Alwar isnt it. Also, I dont think the quality of bodywork would make the Leyland feel less powerful than the Tata.

+1

Unless ALL is using totally different grade of alloy making it heavier by atleast a ton!

Here is something I found about the ALL Buses

[julupani]

At least the brochure confirms the usage of the same engine and tranny. So most probably it was down how aggressive the driver was, or some loss of power due to maintainance issues.

This begs the question, does ALL,like Tata, also have a contract for maintainance of all the 800 odd buses they had to supply or not??

[turbo1787]

The Govt. of Delhi N.C.T was very impressed by the first lot of TATA buses that were there before JNNURM. So when tenders were floated for the other competitors (read AL) the specifications clearly stated that the same engine,trany were to be used as were being used in the TATA Marcopolos(a.k.a Cummins).
I have chatted with a few DTC low floor bus drivers and they said that both the buses (TM and AL) are almost similar to drive. Not even a single driver missed telling me that both being automatics have an extremely poor pickup.
Some of them even said that thankfully that mostly all blueline buses have been removed otherwise these Low floor buses would have been no-match for them.

[directinjection]

Originally Posted by tsk13

Haryana Roadways has Low Floor Volvo City Buses on the route ISBT Kashmere Gate - Ballabgarh. These are the sole Volvos visible amongst Tatas and AL's.

HR's Volvo buses you refer to are diesel engined whereas DTC low floor buses (both TML And AL) are CNG powered. The former are more powerful due to diesel advantage.

Originally Posted by turbo1787

Not even a single driver missed telling me that both being automatics have an extremely poor pickup.
Some of them even said that thankfully that mostly all blueline buses have been removed otherwise these Low floor buses would have been no-match for them.

Poor pick up is due to automatic speed retarder and not engine lacking power. During Commonwealth Games, the DTC buses provided to Games authority for transporting athletes and Games officials had their retarders de-activated on Delhi Police's instructions, in order to increase speed and reduce chances of terrorist attacks. Those buses moved much faster. Later on retarders were activated.

Originally Posted by SAE40 in veins

Both use a Cummins 5.9 liter BG+ CNG unit

The AC ones from Tata are fitted with Cummins C series 8.3 litre CNG engine that develops 280 HP. Bigger engine necessitated due to AC. No idea about AL AC ones. The exhaust pipe of TML AC buses (red ones) is much wider than that on non-AC (green) ones. But in AL buses, even the AC ones use the same exhaust pipe as the non-AC model.

Originally Posted by julupani

This begs the question, does ALL,like Tata, also have a contract for maintainance of all the 800 odd buses they had to supply or not??

Yes. Tata had emerged as the L-1 tenderer in the bid. AL's bid was higher but agreed to reduce its quote to Tata's level. Thereupon, the order was divided between TML and AL in the ratio 65:35. Both faltered in supplying buses on time and are facing heavy penalties.

[Mpower]

Originally Posted by directinjection

Poor pick up is due to automatic speed retarder and not engine lacking power. During Commonwealth Games, the DTC buses provided to Games authority for transporting athletes and Games officials had their retarders de-activated on Delhi Police's instructions, in order to increase speed and reduce chances of terrorist attacks. Those buses moved much faster. Later on retarders were activated.

Speed retarder limits top speed right. How does it affect acceleration?

[MileCruncher]

Originally Posted by Mpower

Speed retarder limits top speed right. How does it affect acceleration?

I think the modern retarders that are linked to the ECM work on fuel flow especially with Auto Transmission else the vehicle will not be at the top most gear at 40KMPH. Faster upshifting because of the speed retarders would also reduce the acceleration right !