[vivek95]

It is common to see intercity Volvo B7R and B9R buses in India to have clocked 12 lakh kms. Most of the first batch of multiaxle Volvo B9Rs owned by VRL have crossed 10 lakh kms and mind you, the buses are still maintained in a great shape. There are reports of Konduskar Volvo B7Rs to have clocked 15 lakh kms on their odo. All this on original engines.

[Rahul Rao]

Dear members and moderators, please excuse me for going slightly off topic initially.


I had entered my business life in 1997 by starting a bus Ac repair workshop, I had assembled bus Ac units too. In 2003 I changed over from automotive air-conditioning sector to taking up Air conditioning projects for office buildings, food processing units pharma companies etc.


I still have contact with the Bus Ac sector, and a good friend is the only manufacturer of Bus Ac units in entire Maharashtra.


In that era a Tata or Ashok Leyland bus used to run a maximum of 700 km a day. About 2 Yrs 4.5 lakh km on OE engine used to be every owners target. the second year low business months of June or July were targeted for preventive overhaul.
In 2002 came the Volvo the first of these buses in Pune used to manage a Pune Nagpur 700 km run in just 12-13 Hrs, and the 1 Lakh km service interval meant idle time in the day could be used for short trips so alternate day these buses ran an additional 300 to 500 km. 1000km a day became the target for many of the bus owners, and even this consumed only 16 to 17 Hrs of operating time leaving spare time for washing the vehicle minor greasing and cleaning air filter (note this is DIY for long service interval commercial vehicles, and keeping efficiency and low end torque in mind 2000 to 3000 km norm is followed instead of recommended 10,000 km) etc.

Volvo also started another trend that is end of life, so a bus that has done 12 years or 30 Lakh km will not receive any support, spares etc from the company. Considering this people started renovating the bus during the first off season after the bus crosses 15 Lakh km, and overhaul or half engine replacement was part of the renovation. There are some bus owners who replaced buses after a period of 5 year. They have managed 17 to 18 Lakh km with untouched engine, a new buyer usually gets all maintenance done, so along with a new coat of paint and new upholstery even overhauling engine is the norm.
Now coming to Tata and AL. According to bus owners as long as the engine has run without overheating with Air cleaner and engine oil changed at decent frequency, these can run about 7 Lakh km untouched. Beyond that oil consumption, lower efficiency etc forces owners to go in for replacement. Tata provides company overhauled engines as replacement, these engines come with 1.5 Lakh km warranty. older fuel pump has to be overhauled at fuel pump vendors outlet, and this takes about two days. Your old engine goes back to the overhaul plant in Jamshedpur for rework and use by some one else.
According to transporters who run both buses and trucks, bus engines last longer, as they have lesser no of cold starts in early morning hours, and they are not switched off at short halts as they also power the Ac compressor. Many buses run about 2000 km before engine is shut off after a start, and this also usually occurs in day hrs. Truck engines are switched off often. Many long haul truck drivers take a halt in the evening rush hours and restart after 10.00 PM or so after two wheeler traffic is less.
Due to all this truck engines live lesser than bus engines.






Rahul Rao

[anb]

Originally Posted by GTO

What is the usual life of truck engines before an overhaul is required?

I worked as Asst. Engineer in a state transport corporation for a couple of years. The average life of Leyland Hino BS2 engine without overhauling was around 6-7 lakhs km. The highest corporation achieved was around 13 lakhs km.

[n.devdath]

Originally Posted by Rahul Rao

Many buses run about 2000 km before engine is shut off after a start, and this also usually occurs in day hrs.

Very informative and insightful post.

However, are you sure it is 2000km before shut off or 200?

Even a long distance bus (Bangalore-Bombay for example) takes a halt for passenger/operator bio breaks approximately every 8 hrs and at an average speed of 80kmph, that translates into 640km.

While one may argue that the engine isn't shut down during these halts by some buses since they run the ac as well, it still doesn't add to 2000km between shut offs.

The longest bus route in India is Bangalore-Jodhpur and that is 1935km. I have travelled on it. Both VRL and Sharma shut off their buses during long breaks in the day for lunch and snacks.


Why do truck engines die sooner?

1. Overloading.
2. Irregular maintenance and jugaad repairs.
3. Bad/rash driving.

[audioholic]

Nice piece of info. I feel that the revolution these foreign manufacturers brought in to the CV industry is better drivetrain and more power. Though I am no expert in CV, if we do a side by side comparo of long distance buses and their drivetrain, the Volvos and Scanias are quite adequately powered to cruise without effort. A bigger engine running at a lower speed is anyday better than an engine, smaller or with lesser power output running close to its maximum potential. Hence, I feel that is also a considerable factor which leads to higher reliability. The Volvo B9R can hit 100+ speeds effortlessly which when driven at 90-100 is far easier for the engine for a prolonged time.

Originally Posted by n.devdath

Very informative and insightful post.

However, are you sure it is 2000km before shut off or 200?

I think its rather the driving cycle which is longer. Shutting off the engine is different compared to the engine cycling between cold and hot states. That makes a difference too. So maybe Rahul or his source meant that the long distance buses cover a greater distance before they fully shut down. Even car engines which do a lot of short distance trips are said to suffer more wear and tear in the long run.

[gauravanekar]

Being in Volvo, I have seen many bus operators take care of the bus with lot of care and pride. Drivers are very well trained and they know how to drive economically and safety. This also contributes significantly towards good engine life

[AMG Power]

Engines that do continuous long distances stay reliable for very long. In fact they do not even need the oil to be changed as per the regular preventive maintenance schedule as the oil would last longer than that of engines that do short distances.

These engines would probably average around 500 kms per day making them ultra reliable.

Rarely would you see a truck parked on the roadside with an engine problem - you will however find them with broken leaf springs, burst tyres, broken axles or maybe just overturned.

[superbad]

Originally Posted by GTO

On the original engine & gearbox! Is this the norm among commercial vehicles? Wow, either way. What is the usual life of truck engines before an overhaul is required?

Depends on their intended usage. A Tatra 8x8s used for towing tank transporters is overhauled every 15 yrs/60,000 km. I know that seems like very low mileage for such a long period but consider the fact that these things are hauling 85 tons when fully loaded & a min of 25 tons at any time, so the stresses on the vehicle & it's drive train are very high.

[Turbohead]

Originally Posted by AMG Power

Engines that do continuous long distances stay reliable for very long. In fact they do not even need the oil to be changed as per the regular preventive maintenance schedule as the oil would last longer than that of engines that do short distances.

Sounds quite interesting! Any proof for that?

Besides, is there any chance our car engines can last so long especially with ridiculous traffic in the city and short trips? I regularly see taxis with 2 lakhs on the odometer. Or are regular cars designed to be junk after 2-3 lakh KM's?

I've warmed up to the idea of retaining a car for as long as possible after hearing of how much cars run in Europe! A friend of mine in Denmark knows a person whose VW Passat has run 7 lakh KM's and it's still on the original clutch! Besides, cars run over 2- 2.5 lakh KM's are good buys there according to him.

[Miyata]

Wow! That is amazing. Massive numbers through the posts. One of the senior IBM employees had a GM car at over 300,000 miles. This was 3-4 years ago. He said all he does is regular scheduled maintenance. Engine, cluthplates, timing belts (!) etc were apparently still original.

Surely those of us looking to make our next change with an EV might try and pull our current steeds those extra miles! No dearth of motivation.

[landcruiser123]

I'm not surprised about the truck running a million km on a stock engine. These beasts of burden are meant to easily run 6-7 lakh km without overhauls.
In the US, manufacturers specify a life called B50. If the engine is rated for 500,000 miles B50 (8 lakh km,) the manufacturers expect that 50% of the engines are overhauled at 500,000 miles if routine maintenance is performed. The other 50% of the engines will have a longer life.

Originally Posted by n.devdath

However, are you sure it is 2000km before shut off or 200?

Even a long distance bus (Bangalore-Bombay for example) takes a halt...

I think 2000 km is correct. Cabins in these buses get extremely hot and uncomfortable when switched off and can be dangerous as the air inside can become stale. Also, trucks need to keep powering the refrigerators if they are carrying perishable goods.

In the US, semi trucks can run continuously.

[mail4ajo]

Has anyone looked at the metallurgy, road conditions and fuel quality as supporting reasons for this long life?

Diesel quality in India has improved vastly over the years. I still remember our family trucks only used certain IOC bunks the knowledge which came from experience.

[sandeepmohan]

Originally Posted by audioholic

I feel that the revolution these foreign manufacturers brought in to the CV industry is better drivetrain and more power.

Absolutely. They have also woken up our local players such as TATA and Leyland. We would have never seen a Prima, Hino powered Leylands or Navistar otherwise. These trucks while still not a patch to the Europeans, are much better off than what they used to have in their portfolio.

Originally Posted by audioholic

Though I am no expert in CV, if we do a side by side comparo of long distance buses and their drivetrain, the Volvos and Scanias are quite adequately powered to cruise without effort.

Not only can they cruise with the least amount of stress, they are comfortable and effortless for the driver, even in hilly terrain. There is so much torque. The only real challenge was the length of the bus which made it tricky to negotiate a hair pin bend.

I still wait for the day we have something close to the likes of a Volvo or Scania and made by our local folks. All I see is product show case at our Auto Expo. None of those buses make it on the road.

[shobhit.shri]

Entirely a conjecture, but probably it's the low RPM and high torque nature of these engines that give them such long life. All the technology around "driving pleasure" takes its toll on engine life.


Also, the jet engines have a life as high as 40000 hours!

[Brumby]

The engines are overhauled on the basis of running hours calculated at an average of 75-90% load. At lower loads the interval becomes shorter. For automobiles the manufacturers mention kms as a maintenance schedule by calculating an average distance that an automobile will cover during that interval. This is done for the ease of understanding.

e.g., lets consider that the recommended engine overhaul interval is 30000hrs.

A car, which can do an average speed of say 50kms/hr will have an overhaul interval of 1500000 kms, where as a truck which will do an average speed of say 35km/hr will have an overhaul interval of 1050000 kms only. So for the same engine the overhaul interval in terms of kilometers is different whereas the running hours are the same. This explains the difference between the higher mileage before overhaul of a light vehicle and a cargo-carrying vehicle.

The components of engines are tested for running hours at optimum load which is between 75-90% of the rated power. Intervals between kms is just a conversion and hence varies for different vehicles.

The overhaul depends on the reliability of the components like inlet/exhaust valves on the cylinder head, piston and piston rings and liners. As long as the lube oil system is maintained at regular intervals, bearings will seldom require any renewal. Usually the piston rings and the inlet/exhaust valves require replacement.

Regards.