[gauravanekar]

Originally Posted by DicKy

Is there any particular advantage for rear engined low floor buses? Except the NVH factor for the driver and front passengers?

If you ask me buses have to be rear-engine every time because:
1. You need more mass in the rear overhang to minimize bouncing of the body in the rear. (Unlike trucks which are predominantly loaded in the backside)
2. Distance between transmission & differential, between Engine and final exhaust increases the efficiency
3. Absence of prop. shaft running through the length of bus frees up gigantic amount of space for luggage
4. You only need to heat insulate rear bottom portion of the bus body as everything is covered in one place
5. Lowfloor body style is truly possible with rear-engine only

The only plus point of having a front engined bus is to share parts with truck chassis, which drives cost benefit to the manufacturer, and not necessarily be of any good to the driver or passenger.

[sandeepmohan]

Originally Posted by landcruiser123

does anyone know how easy is it to access the engine components of a rear-engined bus for repairs?

Super easy. Lift the rear hatch or hood and you can access pretty much everything except the gearbox. Unlike a front engine bus, they use all the space at the back. Basically the entire width of the bus body. Engine placed in the center, accessories such as air conditioning compressor, alternator placed to one side, radiator on the other, is the usual practice.

Its hard to say why they were not dependable. The engines used were the same as the front engine models. Its only the gearbox, where in cases mechanical or hydraulic linkages would be used and had a tendency to fail. Over heating was another problem. Unlike a front engine bus where there is a draft of air flowing through the radiator at all times, these rear engine buses did not have adequate cooling or even forced cooling. If you compare the design to a Volvo, there are ducts to channel air into the radiator from the outside. I don't think we spent enough time engineering a good solution to this problem.

You'd think that when you have a companies like Volvo building only rear engine buses over the last 20 years in India, you'd study and copy the design. That has not happened either.

[SainiAvi]

I do agree with some of the views already posted above.
I attribute the lack of proper ground of design or the lack of a proper study for retro-fitment as a key miss amongst the Indian manufacturers.
Furthermore, the verification and validation seems a bit rushed, to gain on the "go-to-market/get-to-market" times.
But with the new entrants like Volvo, Mercedes Benz Buses, Scania there seems to be a good competitive challenge to Indian manufacturers who have taken up a new interest thanks to the loss of market share to the former auto giants.
With the shift to xEVs it should help make it more easy to achieve such configurations, like how Switch mobility or Tata Motors recent xEVs are rolled/rolling out.

[AutoConsultant]

Having worked for Tata Motors in managing a 100-bus Delhi Transport Corporation (DTC) depot, following were my observations :

• The buses were much ahead of their time tech-wise when they were bought in 2007-08 around the Commonwealth games
• These buses run on a Cummins engine and an Allison Torque converter gearbox - the gearbox was very reliable and most of the complaints for engine were related to overheating due to the extremely high temperatures here in the summer
• Tata motors, at the time of selling these buses, made humongous profits but signed a 15-year annual maintenance contract where they did not estimate the future expenses that well and hence suffered losses year after year
• Due to this, there was a lot of cost cutting involved in the maintenance and hence the conditions of the buses deteriorated

To summarise, the Tata Marcopolo DTC buses were made to be run in moderate climate conditions on smooth roads with recommended passenger loads, none of which was true in this case. Add to that the compromises in maintenance and this is the result.

The product was good but due to lack of testing in real world conditions the buses are in this condition.

[chaudh2s]

These TM/AL RE buses are underpowered as an outcome of Indian mindset to give minimum, and since the driver sits away from engine he doesn’t feel/hears the engine as much as he would when he sits on top of it. So, as I have felt in Delhi/Gurgaon, these buses are driven at very high rpm (just hear sometime how the engine is screaming, begging for mercy). In comparison the Volvo engines are so calm, being adequately powered and made of higher quality, better designed components. This coupled with high ambient temperatures, poor cooling system design, sabotage on easily accessible engine components at the back, leads to frequent engine failures on TM/AL.

[nagaraj15]

Manufacturer himself unable to prepare the budget for maintenance, then how an individual buyer will be able to plan and bear the costs, apart from running, maintaining and to get a profit.
Marcopolo not suitable ? when did they come to the conclusion?, me a layman, one look at the exterior and one ingress in to marcopolo helped me to come to the conclusion. those R&D couldn't come? wonder of wonder

[Rahul Rao]

Originally Posted by lina

There were many cases of Volvo buses also catching on fire. Im pretty sure there is a cooling problem with these buses.

There are time periods of a few months when lot of fire incidents after accidents occur and then suddenly stop occurring.
These are due to other reasons and not vehicle designs.

Originally Posted by lina

in a head-on collision with another truck/bus, the first 10 rows are a definite gonner.

The driver and the door steps are in the crumple zone of the bus, the region where first row of seats starts is a very rigid structure which does not collapse. In front engined buses the rigid chassis on which the engine sits transmits energy right upto the rear.
BTW 2 axle Buses usually have only 11 rows.

Originally Posted by GeeTee TSI

Historically India has been plying trucks under the garb of buses, with no bus specific chassis, drivetrain or suspension till early noughties (that's decades by international standards).

Sorry sir,
TATA Mercedese got the LPO chassis the first dedicated bus chassis in 1954, where as Leyland got the Viking in 1976.
A bus chassis had tapered ends, rubber encasement on leaf springs, a different gear and differential ratio.
Even today a larger percentage of buses world over are front engined, in fact till very recently US rules allowed only front engine chassis on body buses for school bus application.

Originally Posted by GeeTee TSI

That said, the interstate AL front engined coaches are very refined with engine smoothness sometimes rivalling the Volvos (own perception). However inside the passenger compartment thanks to better NVH engineering, the Volvos seem quieter.

NVH is normally due to cost cutting in coach building.

Originally Posted by GeeTee TSI

I wonder if automatic transmissions also fell behind on priorities of homegrown OEMs along with rear engine configuration

You are absolutely correct here.

Originally Posted by gauravanekar

If you ask me buses have to be rear-engine every time because:
1. You need more mass in the rear overhang to minimize bouncing of the body in the rear. (Unlike trucks which are predominantly loaded in the backside)
2. Distance between transmission & differential, between Engine and final exhaust increases the efficiency
3. Absence of prop. shaft running through the length of bus frees up gigantic amount of space for luggage
4. You only need to heat insulate rear bottom portion of the bus body as everything is covered in one place
5. Lowfloor body style is truly possible with rear-engine only

You are correct in point 1,3,4,and 5.
Shorter distance will increase effeciency, not longer.

In yester years we faced two problems, first was import restrictions which did not allow us to import guages and communication components. Due to this in case of rear engine vehicles, problems with engine like overheating were not noticed by drivers till the engine ceased and stopped working.
In front engine the change in firing and engine tone used to be noticed by drivers and repairs done on the spot. In the same era things like oil pipes, hoses etc used to be prone to failure, this was again due to un availablity of compounds due to import restrictions.

By the time all these issues ended Volvo entered the market and no one wanted to test new developed products from established players.

First true rear engine buses in India were made by Kirloskar Neoplan in 1989 followed by Autorola in 1992.

[ritedhawan]

Originally Posted by AutoConsultant

Having worked for Tata Motors in managing a 100-bus Delhi Transport Corporation (DTC) depot, following were my observations :
[list][*]The buses were much ahead of their time tech-wise when they were bought in 2007-08 around the Commonwealth games[*]These buses run on a Cummins engine and an Allison Torque converter gearbox - the gearbox was very reliable and most of the complaints for engine were related to overheating due to the extremely high temperatures here in the summer
.

I used to travel in DTC buses during the course of Commonwealth games and post that as well , whether with AC or Without AC. It is without a shadow of a doubt that Delhi Summer's are unforgiving. Add to the fact that the main Ring roads in Delhi are 'chock-o-block' which vehicular traffic especially during peak office hours which would mean bumper-to-bumper traffic. These buses run on CNG which in essence is a 'dry' fuel and therefore cannot be expected to provided that small amount of lubrication which liquid fuels provide. Thus the onus of providing the lubrication is solely with engine oil. Then those scorching Summer temperatures of Delhi and overloading of buses during peak hours. In unison, all these factors were working to bring down those hapless DTC buses!

I had this habit of positioning myself behind the driver and I could see that the moment a DTC bus approached a flyover:

(1) The driver would push a button to switch off the AC (If it were an AC bus).
(2) The driver would bring the transmission to manual mode and would set it to gear 1\2 in order to approach the incline on the flyover.
(3) They would push the throttle and the engine would scream. Even if I were standing behind the driver , I could hear the screams of the engine, as if gasping for air!

There is another reason for the breakdown, other that the usual over heating issue due to which I believe most of the DTC buses would breakdown. This could be related to stressing the transmission: The drivers that DTC hired had this habit of consistently pressing the break pedal and transmission set to 'D' or for that matter manually set to '1' or '2'. Even though the bus was at a Red light stop. I could not understand why the driver couldn't bring the transmission to 'N' and then continue to put his foot down on break pedal as long as he wants. As if he is doing it out of compulsion! I have seen many DTC driver's do this, they bring the bus to a stop at the Red light , they continue to put their foot down to break pedal, additionally the driver would pull some sort of a liver which I presume was hand break. I mean , he is scrupulous enough to pull hand break along with putting his foot down on the break pedal so that the vehicle wont move. Why not release the stress on transmission!!? , No, he just wont do that!

Then you would hear the engine noise increase and decrease as the Torque converter is still engaged and the RPM of the engine going through some kind of a curve!

[RGK]

My opinion of rear-engine buses, particularly Volvos, is that we have seen a lot of horrifying fire accidents where the diesel tank mounted before the engine , burst (due to the accident) and spray the fuel on the heated engine, starting the bus on fire and causing a lot of casualties.

[Anwesh]

Originally Posted by vharihar

This is an uninformed viewpoint. Unlike personal items like phones and cars that are aspirational in nature, for commercial vehicles travellers don't notice the brand at all. If you provide adequately comfortable seating and interiors, it'll still sell well even if it's a TM or an AL.

Sorry, that is not an uninformed viewpoint. It is factual information shared on the basis of my personal first hand experiences and observations. My Learnings from a full time automotive sales career spanning the prime years of my life, till 2016. Of these, 27 years were in the CV sector, and 2001 onwards , 100% dedicated to the bus sector, as seperate verticals were created for each segment. During the period when I was active as a frontline sales warrior, climbing from executive to senior manager level, the brands that I handled are AL, Allwyn Nissan, Telco, Tata, Eicher, Sutlej and Corona in India + DAF and Mercedes Benz in Africa.
I have had one to one business relations with prominent fleet operators and senior managers of public transport undertakings. I have secured orders from them and executed successfully. I have developed RII calculator spreadsheets, before manufacturers came up with sophisticated fleet management softwares.

I am not active in the the automotive sector 2016 onwards, am into something totally different now, but regularly connect with some old colleagues, close friends really, who are very much there so I can keep abreast of the current scenario.

In fact , it is your posts that are mostly uninformed, in this topic and elsewhere. But I shall not discuss that here, it will take this discussion OT.

Firstly, regarding passangers wanting to travel in Volvos only, that was very much the scenario during the first decade of this century. The upper middle class was also travelling by coaches during those days, and Volvo was the benchmark. Customers have fought , raised a ruckus at the boarding point, if the booking guy had said a Volvo, and a MB coach arrived instead. And if it was Corona, the situation was even worse. Matters have reached police stations and consumer courts.
The MSRTC Shivneri Volvo coaches are on hire fro private owners. Initially both Volvo and MB were approved. After the first two MB coaches were supplied, MSRTC was bombarded with complaints by passangers, prompting the management to ask the contractor for replacement with Volvos.

Now, coming to the original subject of this topic, why AL and Tata does not have luck with rear engine buses, ( Tata was added later on),
The short answer is that both are very much capable of designing and launching highly capable diesel powered rear engine buses, but it is not worth it.

The long answer, is that both are very much capable of designing and launching highly capable diesel powered rear engine buses, but it is not worth it.

Further expounding, Let's first understand that a RE bus/coach requires a beefier driveline compared to a FE bus of the same size.What a six litre engine can do comfortably in FE layout, a minimum seven litre engine is required for the same task in RE application. So , once a bigger engine is choosen, the entire drive line has to be upgraded, and as the driveline is more powerful, all systems like the cooling system, electricals , brakes etc have to be upgraded. The chassis frame, body structure has to be strengthened. So in the end, you get a bus that is as good as a Volvo, costing nearly the same. So who will buy a AL or TaMo bus at Volvo equalling price? And why should AL and TaMo go through all this headache for 2% market share?

Yes! 2% market share is what Volvo had at the peak of their sales, about ten years ago. They were selling approximately 800 to 900 buses per annum when the HCV bus market was around 40000 units a year. Now, sales have totally tanked for Volvo, probably zero. Why?

The price of a single multiaxle is above 1.5 cr. The price of a PAIR of 12 mtr. FE coaches AL/TaMo/BB/Eicher is around 1.25 cr. The second option is the only somewhat financially viable option for the operators, the first is financial suicide. In fact, finance companies also are not interested in financing the first option, the second one also they shall take up only if the borrower is an established operator with a perfect repayment record.

The above applies to Intercity/interstate buses. For intracity, the choice has moved to electric for premium a/c citybuses in the HCV catagory. TaMo is already in this segment for the last few years. Their hybrid buses are operating in Mumbai BKC, and since last year 12 mtr. full electric are also doing very well in BEST.
For AL switch mobility has secured Mumbai double deckers order.

The RE coaches, buses that were launched are,
1)Kirloskar Neoplan / Autorola / Corona
2)AL Panther/ Luxura / 12M-RE
3) Volvo
4)Tata Starbus / Divo
5)Scania
6) Mercedes Benz
7)Sutlej Lexia
8)Hino
9) Isuzu

I shall write about each of these in subsequent posts ,

Originally Posted by AutoConsultant

Having worked for Tata Motors in managing a 100-bus Delhi Transport Corporation (DTC) depot, following were my observations :

• The buses were much ahead of their time tech-wise when they were bought in 2007-08 around the Commonwealth games
• These buses run on a Cummins engine and an Allison Torque converter gearbox - the gearbox was very reliable and most of the complaints for engine were related to overheating due to the extremely high temperatures here in the summer
• Tata motors, at the time of selling these buses, made humongous profits but signed a 15-year annual maintenance contract where they did not estimate the future expenses that well and hence suffered losses year after year
• Due to this, there was a lot of cost cutting involved in the maintenance and hence the conditions of the buses deteriorated

To summarise, the Tata Marcopolo DTC buses were made to be run in moderate climate conditions on smooth roads with recommended passenger loads, none of which was true in this case. Add to that the compromises in maintenance and this is the result.

The product was good but due to lack of testing in real world conditions the buses are in this condition.

IIRC this order was almost equally devided between TaMo and AL. Both supplied buses with identical engines and transmission, Cummins B series and Allison. AL used Meritor axles, while Tata used their own axles. Both were reluctant to supply with a/c they knew it shall not work well but were forced to supply some

The problems were for both makes , Tatas gained publicity.



thank you all.

[GeeTee TSI]

Originally Posted by Rahul Rao

Sorry sir,
TATA Mercedese got the LPO chassis the first dedicated bus chassis in 1954, where as Leyland got the Viking in 1976.
A bus chassis had tapered ends, rubber encasement on leaf springs, a different gear and differential ratio.
Even today a larger percentage of buses world over are front engined, in fact till very recently US rules allowed only front engine chassis on body buses for school bus application.

You have stated an interesting information, but configuration you mention has been long ditched for city applications the world over, in favour of low floor, rear engined, air suspension buses (I recall the amazement of travellers from India back in the day on the 'kneel' function of city buses in Europe)

That's what is qualifies as an everyday bus in my view

That said, the Switch AL electric buses offers all the comforts without the rear engine conundrum!

[Anwesh]

Originally Posted by Anwesh

The RE coaches, buses that were launched are,
1)Kirloskar Neoplan / Autorola / Corona
2)AL Panther/ Luxura / 12M-RE
3) Volvo
4)Tata Starbus / Divo
5)Scania
6) Mercedes Benz
7)Sutlej Lexia
8)Hino
9) Isuzu

I shall write about each of these in subsequent posts ,

Please add Serita, KingLong to this list.

Regards,

[Rahul Rao]

Originally Posted by Anwesh

The RE coaches, buses that were launched are,
1)Kirloskar Neoplan / Autorola / Corona
2)AL Panther/ Luxura / 12M-RE
3) Volvo
4)Tata Starbus / Divo
5)Scania
6) Mercedes Benz
7)Sutlej Lexia
8)Hino
9) Isuzu

I shall write about each of these in subsequent posts ,

AL still makes the 12 M-RE chassis. It is exported to Lanka Ashokleyland in kit form and body built there.
https://lal.lk/our_products/12m-rear-engine-ac/
https://lal.lk/our_products/ule/

Rahul

[Reinhard]

Originally Posted by RGK

My opinion of rear-engine buses, particularly Volvos, is that we have seen a lot of horrifying fire accidents where the diesel tank mounted before the engine , burst (due to the accident) and spray the fuel on the heated engine, starting the bus on fire and causing a lot of casualties.

The chances of this happening - would be rather slim IMO. Its more probable that the fire already started due to some other reason (like electrical fire) and eventually the diesel contributed to it much later.

Just by bursting open and spilling diesel - a fire cannot be started instantaneously - unless the ambient temperature is well over 55Deg C (which is typically the diesel flashpoint).

[SKC-auto]

Originally Posted by Anwesh

What a six litre engine can do comfortably in FE layout, a minimum seven litre engine is required for the same task in RE application.

Wanted to understand the reason behind this, as others have said RE will have shorter shaft compared to FE, then the losses should be minimum?