[apoorv agha]

Hi BHPians,

I have observed a very unique thing in large trucks and trailers plying on Singapore roads. As per my understanding and observation, the large trucks ( Class 8, as they say for ones above 15 Tonnes of Gross Vehicle Weight) in India bear a single number plate for a truck and trailer combination. However, in Singapore, a truck or a prime mover has separate number plate and the trailer has a separate number plate attached to it. This means the trailer is registered separately and is not married to the same truck, or in other words a prime mover can rotate between trailers. Now, the biggest advantage of this is the increased efficiency and a higher turn around.

Currently in India almost 80% of Class 8 trucks are rigid and only 20% as tractor-trailer combination, whereas in other countries, Class 8 trucks are mostly tractor-trailer combination.

You can see a Fifty years old photograph which depicts correct and more efficient way of using tractor trailer combination ( How far are we lagging behind )

[TheARUN]

The answer might look stupid, but let me still explain

Look at the way toll is charged on our highways, rigid trucks get charged a specific rate and tractor-trailers a substantially higher rate. Now, a 2 axle truck and a 5 axle truck get charged the same toll, they carry loads of 10 tons and 30 tons respectively. Even manufacturers are encouraging this practice, Tata and Leyland have launched 5 axle trucks that can carry as much as a tractor-trailer can 'pull' but still get charged less at the toll plaza

In India too, it is possible to have a trailer registered separately, as a boy I remember seeing different numbers on a farm tractor and its trailer, what I think the operators do is just register the prime mover and copy the number to an unregistered trailer

Volvo trucks came into India and started selling this very same concept of tractor-trailer and quicker turn-around times, but nobody put money on their idea

One thing is for sure, the market is evolving, we are slowly catching up with the West and China, maybe in another 15 years you would see this happening. As far as trucking goes, I think we are still stuck in the '2-stroke'age, remember how a few years back all two wheelers were two stroke vehicles with only the Bullet being 4 stroke, now all two wheelers are four stroke!

[Sreedharan]

If you could see in the picture, the third picture of a (bent chassis) is a "2 axle" truck and the next picture is "3 axle" truck. Hence it can be understood why it could carry more. I feel its more of a marketing gimmick.

Now coming to Indian scenario,
Trucks up to 16.2 ton, can manage with a 2 axles. If we go for a trailer type, it will increase one more axle and makes it less efficient. (lesser FE and higher tire wear)
25ton onwards, we need a trailer only for carrying voluminous goods. Example: Single axle trailers hitched to a 2 axle prime mover carrying containers to ports.
If it is a going to carry normal or dense goods, it only requires lesser loading span and hence does not make sense in going for a trailer.
40t and 49t tractors comes into picture where there is a unique requirement to carry heavy goods, which also takes up space. eg: Wind mill parts, Boilers, Cement bags etc.,

Originally Posted by TheARUN

The answer might look stupid, but let me still explain

One thing is for sure, the market is evolving, we are slowly catching up with the West and China, maybe in another 15 years you would see this happening.

I feel that tractor trailers are not an evolution. Rigid trucks will still have their dominance as they cater to different applications. Moreover Tractor Trailers comes with their own problems related to handling and braking (eg. jack knifing).

Originally Posted by apoorv agha

Hi BHPians,
( How far are we lagging behind )

To sum it up, i would say that we are not lagging behind in any terms w.r.t truck efficiency (infact we might be among the top few in the world). however, we will have a lot of catching up to do in terms of freight safety, occupant safety, fellow road user safety, driver comfort and so on.

[Bookkeeper]

Originally Posted by apoorv agha

Currently in India almost 80% of Class 8 trucks are rigid and only 20% as tractor-trailer combination, whereas in other countries, Class 8 trucks are mostly tractor-trailer combination.

Aren't rigid body trucks shorter in length than tractor trailer combination? Maybe not all but most of them.

So maybe this might have something to do with the fact that given the space constraint in India shorter length rigid body trucks are preferred for better maneuverability.

I may be wrong so feel free to correct me.

[sudev]

FE does not only depend on number of tyres but much more on load per tyre and deformation due to load. If more tyres meant more fuel then railways would be out of contention.

The argument favouring hitches and quick turnaround goes out of the window when the time at tolls and nakas takes much more than journey time.

AFAIK the tolls are now based on number of axles and not on horse plus trailer. Yes Horse trailer combo would have at least one additional axle.

[Sreedharan]

Originally Posted by sudev

FE does not only depend on number of tyres but much more on load per tyre and deformation due to load.

FE is highly dependent on the no of axles. Reason: With each tire, the rolling resistance goes up. That's why the concept of lift axles came in to existence. (Lift the axle when on partial or no loads so that fuel and tire mileage can be increased)

Originally Posted by sudev

If more tyres meant more fuel then railways would be out of contention.

More tires always means less FE. In case of railways too, more axles will require more energy (one rail coach carrying 50ton load with 10 axles will demand less energy compared to the one with 12 axles doing the same job)

However if you compare railways to roadways, railways will be cheaper in terms of cost/ton/km. The main reason is rails offer lesser co-efficient of friction than roads and hence require lesser energy to move equivalent load. (That's why rails have longer stopping time while brake is applied as they lack friction between rails and wheels)

[sudev]

Going OT but you missed important part of my statement : "FE does not only depend on number of tyres but much more on load per tyre and deformation due to load."

Agree with you that lower number of axle better fuel efficiency.