[fx45]

i dont understand why they chose to make it look like a VOlvo clone..

why cant they be different. it looks like a Chinese Volvo Copy.

[Glifford]

Originally Posted by arpandiv

I have seen a couple of Heavy vehicles with a metal circular ring welded onto the front wheel hubs.
what is the purpose of the same?

Not sure if this was responded to Arpan, but I deduce these are for safety reasons.

Most CVs that have multiple tyres on each rear wheel have rims that are designed to do service both on the front and the back.

In the front they mount it in such a way that the hub gets encased by the rim and in the rear they mount two wheels back to back so the inner rims encase the hub and the outer ones are hollow inside! Check out any truck to notice this!

Now because of this the fastening nuts of any truck jut out of the wheel (unlike in cars). This can be a major safety hazard. Imagine something getting caught between those huge nuts when the wheel is rotating.

Putting this (often thin sheet metal) ring that encloses the nuts ensures that in case anything does touch the wheel gently slips off the smooth ring instead of getting entangled in between those nuts!

I guess the Volvos were the first to feature them. I hope they become a standard soon.

Just imagine you are stuck in a traffic jam between huge trucks and the front wheel hub of just one brushes against your foot! Ouch!

[Ram]

Originally Posted by Glifford

...I guess the Volvos were the first to feature them. I hope they become a standard soon.

Just imagine you are stuck in a traffic jam between huge trucks and the front wheel hub of just one brushes against your foot! Ouch!

Present day CVs in India may be ignoring them but this protective "nickel-plated" ring was also found on the 1950 Leyland B.E.S.T. buses of my childhood. The ten studs and lug nuts were behind this bright nickeled ring.

[Glifford]

Originally Posted by Ram

Present day CVs in India may be ignoring them but this protective "nickel-plated" ring was also found on the 1950 Leyland B.E.S.T. buses of my childhood. The ten studs and lug nuts were behind this bright nickeled ring.

Nice!

Like the saree guard and front number plate (that some of us consider senseless) on 2 wheelers, I guess the norms should dictate its usage.

I guess I saw them on the AMWs as well, will look for them the next time around!

[Blue Thunder]

Originally Posted by Ram

By the way, it's a NEOPLAN Starliner, not a MAN Starliner, albeit Neoplan is now a division of MAN.

Engine
It's powered by a Euro-4 compliant straight-six 12.4 litre MAN D2676 LOH 480 bhp@1900 rpm common-rail diesel engine mounted vertically in the rear. Torque is 2300 Nm @ a flat 1100-1400 rpm -- the highest for a bus.
...

mounted vertically, Ram ?

I was only aware of transverse mounting in the rear.

.

[Glifford]

Originally Posted by Blue Thunder

mounted vertically, Ram ?

I was only aware of transverse mounting in the rear.

.

I can make a guess here.

Longitudinal and transverse mounting applies to the angle of the crankshaft axis with the direction of motion of the vehicle.

Long ago I remember reading in some engineering text book on auto engineering that bus engines are normally laid horizontal to save space. This means the bank of cylinders (in I engines) is laid horizontal (i.e. parallel to the ground).

This would be the case with boxer engines as in Subarus, BMW motorcycles and even our very own Hero Honda CD100 family of bikes.

I guess the cylinders here would be vertical as is the case with most our car/truck engines.

[Ram]

Originally Posted by Blue Thunder

mounted vertically, Ram ?
I was only aware of transverse mounting in the rear.

Originally Posted by Glifford

I can make a guess here.

Longitudinal and transverse mounting applies to the angle of the crankshaft axis with the direction of motion of the vehicle.

Long ago I remember reading in some engineering text book on auto engineering that bus engines are normally laid horizontal to save space. This means the bank of cylinders (in I engines) is laid horizontal (i.e. parallel to the ground)...

...I guess the cylinders here would be vertical as is the case with most our car/truck engines.

You're absolutely right, Glifford.
The Starliner has a vertical (upright), longitudinally mounted rear engine.
It is a 12,419 cc six-cylinder unit with a max. output of
480 bhp@1,900 rpm and 2,300 Newton-metres of torque over a flat 1,100-1,400 rpm range.

BTW, we saw a 1955 Leyland Tiger Cub bus chassis at the BEST bus museum in Anik, Mumbai. This had a horizontally mounted six-cylinder engine. I will describe it in detail in a later post.

[dkamath]

Originally Posted by Glifford

I guess I saw them on the AMWs as well, will look for them the next time around!

Speaking of the AMW's, there was one AMW dumper truck parked for about a week, outside the Basavanagudi Police Station, with some shunt at the front end. Yes, it did have the protective ring on the front wheel hub.

[condor]

Glifford : ... bus engines are normally laid horizontal to save space.

Is it to save space ? Or is it for ruggedness & simplicity of design ?

FWD cars is where you typically use transverse mounting. But for RWD, a longitudinal mounting is preferred. And space is less of a constraint in a bus than in a car.

[Glifford]

Originally Posted by condor

Is it to save space ? Or is it for ruggedness & simplicity of design ?

FWD cars is where you typically use transverse mounting. But for RWD, a longitudinal mounting is preferred. And space is less of a constraint in a bus than in a car.

It sure is space saving! Bus engines are relatively HUGE when compared to our cars! And many have just (yes just) 6 cylinders, so you can imagine their stroke length.

Putting it horizontally would mean the engine (and transmission) would virtually rest between the rear wheels and hence the floor could be lower (a very important requirement)!

Infact space is more of a constraint in a bus (every square inch brings in money) than cars where you have the engine bay and the boot going virtually unutilized!

[fx45]

that protective ring can be seen in mumbai with most of the newer gen fire brigades.. the TATA 1613 ones.. and also recently the CNG Midi buses introduced by BEST. these are ashok leyland ones.

can any one give me mroe information on the BEST museum in Mumbai?

[Ram]

Originally Posted by condor

Is it to save space ? Or is it for ruggedness & simplicity of design ?

FWD cars is where you typically use transverse mounting. But for RWD, a longitudinal mounting is preferred. And space is less of a constraint in a bus than in a car.

Origins of the FWD transverse engine design
The transverse mounted engine was used in the 1931 DKW Front, 1947 SAAB-92, 1950 Borgward Goliath GP 700, even the 1952 DKW Schnellaster F89L van.

But the English speaking world only saw it for the first time in the 1959 Mini, designed by Alec Issigonis.

There was even a RWD rear mounted transverse engine design bus!
The 1961 Leyland Atlantean PDR1/1 double decker bus operated by Bombay's BEST, had a rear mounted transverse engine. That was the world's first rear-engined, front entrance double-decker bus.

A design objective was to ensure that the engine did not intrude into passenger carrying space.
Here is my sketch of the 1961 Leyland Atlantean.

And here is its radiator in the BEST museum in Mumbai.

Constraints
Bus manufacturers wanted no intrusion of the engine into the passenger space at all. Period!

Underfloor engined single deck bus designs, like the BEST's 1955 Leyland Tiger-Cub raised the floor height, notwithstanding the horizontal mounting -- the piston strokes went left to right. The slightly higher floor still needed additional steps at the entrance.

Here is my sketch of the 1955 Leyland Tiger Cub.

Here's a pic of the badge on the front of the bus.

Ram

[condor]

Glifford : It sure is space saving! Bus engines are relatively HUGE when compared to our cars! And many have just (yes just) 6 cylinders, so you can imagine their stroke length.

Infact space is more of a constraint in a bus (every square inch brings in money) .. !

Stroke length is not of much consequence here.

Space is not so much of a constraint in busses. Also, You are comparing engine bay space with passenger -usable space.

With cars, we are talking of engine & GB size & Space w.r.t engine-bay. That's why transverse mounting is good in the car.

Even speaking of passenger-usable space in a bus :
1. I would not want to sit on the engine. not for longer rides, even within city.
2. One seat space in 50 is not as bad as 1 in 5 (car)

3. The engine area in a bus is cordoned off anyway.
4. If I were driving, I wouldnt want anyone within an arm's lenght of me. Not near the gear level, not sitting on the engine cover.

Another factor is about the transmission & steering. Busses dont have (normally) steering controls AND power transmission to the front wheels. So they dont need transverse mounting, when in RWD.

For rear mount engines, the engine may be transversely placed - but again, that's without the steering assembly. (most times - I'm not talking of vehicles with steerable rear wheels).

[Ram]

Maximizing space utilization is what has driven advances in bus design. That is what inspired Leyland's Royal Tiger and Tiger Cub and Atlantean path-breaking designs.

Transverse mounting complicates power delivery.
The flywheel and clutch/torque converter is either on the left or right.
So convoluted schemes have to be devised to take that power to the gearbox and then to the differential and wheels.
This challenge increases When power and torque are huge, as for a bus or truck engine. Drive chains and belts are only for low bhp cars.

Mixing steering controls AND power transmission to the front wheels
have nothing whatsoever to do with transverse mounting.
Steering is the easiest thing to do, even for a driven wheel. Man has done it since world war two if not earlier.

[Glifford]

Originally Posted by condor

Stroke length is not of much consequence here.

Space is not so much of a constraint in busses. Also, You are comparing engine bay space with passenger -usable space.

With cars, we are talking of engine & GB size & Space w.r.t engine-bay. That's why transverse mounting is good in the car.

Well most buses have a one box architecture (except the good old US school buses). Cars as we know have a 2 or 3 box architecture (the passengers sit in one of those boxes).

Originally Posted by condor

Even speaking of passenger-usable space in a bus :
1. I would not want to sit on the engine. not for longer rides, even within city.

Well you must be mistaken! As you have read from several threads here, the best long distance and city buses you have in India (till date) are undeniably the Volvos. And in the Volvos if you are in the last seat row (or the one ahead of it) you ARE sittine ON the engine (atleast directly above it!

On a side note, you sit on the engine even on an RE Autorickshaw

Originally Posted by condor

2. One seat space in 50 is not as bad as 1 in 5 (car)

True

Originally Posted by condor

3. The engine area in a bus is cordoned off anyway.
4. If I were driving, I wouldnt want anyone within an arm's lenght of me. Not near the gear level, not sitting on the engine cover.

That would hold true only in traditional body on chassis type buses like we see in the old Truck chassis based Tata and Ashok Leyland buses! Where the engine would be one grumpy mound next to the driver seat and one long windy gear lever sticks out from behind (sometimes above) it.

Originally Posted by condor

Another factor is about the transmission & steering. Busses dont have (normally) steering controls AND power transmission to the front wheels. So they dont need transverse mounting, when in RWD.

Steering control is to the front wheels.

And the reason why FWD is so popular nowadays in passenger because it is space saving and economical to mass produce (besides other reasons). Serious enthusiast cars are still RWD.

No point in having a bus or a truck FWD since most of the load is on the rear wheels, so traction is best there. So whether the engine is in front or in the back and whether the installation is longitudinal or transverse, the drive is most efficient if it is (primarily) to the rear wheels.

The Matador is a notable exception to this tho!