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Old 3rd May 2007, 21:59   #31
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The volvo B7R chassis[courtesy volvo india website]

I am not too good at this but think this is not a spaceframe chassis.
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Old 3rd May 2007, 22:05   #32
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What about those old Greyhounds? Are they sleepers?
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Old 3rd May 2007, 22:26   #33
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Quote:
Originally Posted by rahul_intlad View Post

The volvo B7R chassis[courtesy volvo india website]

I am not too good at this but think this is not a spaceframe chassis.
Thanks rahul, this is what I was asking for. Its a ladder frame chasis so any conventional indian bus manufacturer can tinker around with the Body on top quite safely.

For space-frame busses, (or modular coaches) its (the upward customization) not done so easily without factoring in load calculations which I dont think the normal indian bus body builders can do.

Greyhounds are not sleepers, they are normal reclining airline seats. But god, I had a ride in them earlier and vowed not to ride in them again although this is OT.

Last edited by 1100D : 3rd May 2007 at 22:29.
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Old 3rd May 2007, 22:32   #34
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The first time I heard about sleeper buses when P.K Travels(Calicut-Bangalore) introduced a sleeper but with fair of around 600RS/person for an air conditioned ride to Bangalore, sometime in 2001.
Those were not B7R, but Sutlej built bodies on Tata(or maybe leyland) chasis
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Old 3rd May 2007, 23:23   #35
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few of those sleeper coach volvos were made by the APSRTC for the tirupathi-hyderabad,tirupathi-vizaag and a few other places like shiridi. but later gave up for the cost per person was real high! and the dint run well either.

the fare was around 850 per ticket for the vizag and the hyd trips dont remember the fare for the shiridi trip from hyd.

Last edited by rider60 : 3rd May 2007 at 23:35.
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Old 4th May 2007, 07:06   #36
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Quote:
Originally Posted by 1100D View Post
For space-frame buses, (or modular coaches) its (the upward customization) not done so easily without factoring in load calculations which I dont think the normal indian bus body builders can do.
What on earth is a space-frame bus? Haven't heard of any such thing.
Is it a good time for a body-engineering. discussion?

Here goes...

Ladder chassis.
World's earliest kind of chassis.
Basically two longitudinal rails joined by multiple lateral and crossed braces.
The rails take up acceleration and deceleration forces.
Lat braces provide torsional firmness and take the cornering and lateral yaw loads. Naturally, the "Z" dimension is weakest. (as in: vertical loading, speed-breakers and potholes).

Backbone
For small sports cars, there's the fibreglass body on a rigid steel tubular backbone. This is used in the Lotus Esprit. Also Fibreglass body on a lattice TSF backbone. This is used in the TVR.

Steel, ULSAB and carbon-fiber monocoques

Steel monocoque (aka integral body or unibody)
is a one piece integrated chassis-body.
99% vehicles use it. Copiously uses metal, so you can build-in crumple-zones.
Hopelessly heavy. Only makes sense when you can afford a huge factory with
facilities for huge stampers, expensive moulders and welding robot assembly lines.

ULSAB (Ultra Light Steel Auto Body) monocoque
ULSAB uses steel too thin for the steel-monocoque stamping presses.

Basically a thin steel tube is placed in a shaping die.
Then very-high pressure (300 - 1500 bar) hydraulic fluid is pumped into the tube.
The fluid expands the tube to assume the inner surface of the die.
This is called hydroforming.

Uniform fluid pressure gives uniform steel thickness, unlike the earlier stampings.

Panels for ULSAB usually use sandwich steel -- two very thin steel skins with a sandwiched polypropylene core. This yields excellent rigidity and very low weight. But you cannot use welding. You will melt the polypropylene sandwich. Panels must be riveted or adhesive-bonded.

For doors, hoods, deck lids and hatchbacks, there's the ULSAC (Ultra Light Steel Auto Closure). Yields door structures that are 46% lighter than average frameless doors.

Invented in 1998, ULSAB will eventually replace conventional monocoque. Meets tough structural and crash criteria while weighing 25% less than steel monocoque. Used in BMW 3-Series.

Carbon-fibre monocoque
The name is self-explanatory.
The world's first carbon fibre monocoque bus was the 1988 Neoplan Metroliner. This is a city bus, with a small diesel engine on the roof that charged batteries under the floor, that powered the bus using electric motors.



Let's come to Space Frame construction.
Steel and Alloy space-frames

Steel space-frame
The 3d tubular-steel space-frame has much better strength than the ladder chassis.
circular sections provide max. strength.
Square sections easy to put the body panels on.
Weak areas are the door sills.
These must be high to take the bending stresses.
So no choice but to use Longitudinally hinged doors (aka Gullwings)
or Horizontally hinged doors (like the Countach).

Alloy space-frame (ASF)
The material used is high-strength aluminium alloy.
With this material you construct
the components of the space-frame, viz.:
  1. aluminium extrusions
  2. pressure die-cast nodes
  3. aluminium sheet stampings
At the corners, where extrusion meets extrusion, you use the pressure die-cast nodes. These take the stresses. Everything is bonded together by laser welds.

This is very space efficient yet lighter than steel monocoque.
Audi A8 was the world's first mass produced ASF-chassis car.
...end of my body-engg. gyaan.

The Volvo B7R is a simple ladder chassis -- world's earliest form of automotive construction.

Ram
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Old 5th May 2007, 01:19   #37
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What is the chassis on which the Mercedes Benz Citaro or even the Old Marcopolo coaches were based on, I dont remember seeing a Tata/Ashok leyland type Lader on opening the luggage hold. Moreover what chhasis does the Low-floor busses have (definitely not ladder).
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Old 5th May 2007, 12:37   #38
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That was a very informative post Ram.
The Volvo buses have a cargo area through which one can walk through to the other side. And this cargo area is flat very low and quite big and can swallow even a Bullet. But I've seen at the central section of the cargo hold there's a lower ceiling area and my guess is that the ladder frame is inside that enclosure. So the loading area is actually below the chassis of the bus.

Last edited by Sankar : 5th May 2007 at 12:38.
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Old 5th May 2007, 19:31   #39
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Its an original b7r for sure but i think its an after market job. the ones coming from the factory directly even have the volvo logo upfront (between the headlights).its missing here.

last month, i travelled between 5 cities, using the b7r four times.

Bangalore-Mangalore :overnight KSRTC volvo. The driver didnt know how to change gears, may be he was new to the volvo, cudnt hear the engine sound and was upshifting with half accelerator!

Mangalore-Davangere : cudnt find a volvo service, used a push back ashok leyland bus. ok

Davangere-Pune : Sharma Volvo. Noticed the driver shiftin to neutral at the slighest hint of a decline in the road!

Pune-Davangere : NWKSRTC volvo. Nice serive, even the lights above the seat worked!

Davangere-Mumbai : VRL. Nice service, again noticed the driver shiftin to neutral for kms and kms at the slighest slope!

took sleeper volvo from belgaum to goa in march. in my personal opinion, sleepers feel good when the road is straight, on curves, you tend to move a lot and if you just had food before getting on the bus,you r going to puke for sure!

@sankar : yes the loading area is below the seats as written by you. at night, when the bus is parked in the destination city, i have seen the driver/conductor sleep in the luggage area

Last edited by BunnyPunia : 5th May 2007 at 19:34.
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Old 6th May 2007, 12:28   #40
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Quote:
Originally Posted by BunnyPunia View Post
@sankar : yes the loading area is below the seats as written by you. at night, when the bus is parked in the destination city, i have seen the driver/conductor sleep in the luggage area
What I said is it's below the chassis rails!!
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Old 8th May 2007, 04:39   #41
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Quote:
Originally Posted by Sankar View Post
Quote:
Originally Posted by BunnyPunia
@sankar : yes the loading area is below the seats as written by you. at night, when the bus is parked in the destination city, i have seen the driver/conductor sleep in the luggage area
What I said is it's below the chassis rails!!
Actually, no!

While the loading area is indeed below the floor of the passenger cabin,
the luggage sits on a strengthened floor above the chassis rails.



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Old 8th May 2007, 19:03   #42
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Quote:
Originally Posted by ram View Post
Actually, no!

While the loading area is indeed below the floor of the passenger cabin,
the luggage sits on a strengthened floor above the chassis rails.

Ram
But ram if you compare the pic you posted and the pic which was posted earlier there's no way the luggage compartment would sit above the chassis rails if the chasis is the first pic one. If it's so then the luggage compartment would be too high above the ground. You can see the chassis rails sitting pretty high when you compare it with wheel height. My assumptions were based on the first pic.

In the picture you positioned the engine is mounted transversely but in the B7R the engine is positioned longitudinally.

Last edited by Sankar : 8th May 2007 at 19:07.
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Old 8th May 2007, 19:13   #43
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Quote:
Originally Posted by ram View Post
Actually, no!

While the loading area is indeed below the floor of the passenger cabin,
the luggage sits on a strengthened floor above the chassis rails.



Ram
This is the chassis of the Low-floor bus. I checked some other Low-floor busses as well and they look similar. However the body above this chassis can be conveniently altered with (irrespective of low-floor or the intercity application).
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Old 8th May 2007, 19:59   #44
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1100D is right, the pic is for a low floor bus which has no luggage area. This type of bus is called "transit bus". The buses used for intercity travel is called "intercity coach". In order to keep the CG low, they raise the passenger seats and put luggage below.

In our desi country buses, the luggage is put on a roof carrier which is not good for aero,stability or convenience.

Now, back to the sleeper, its a great idea. Can anyone post pictures of interior. I'd like to see the seating arrangement. Is is similar to our Indian railway compartments?
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