Bus design

[Pyewipecarshed]

Dirt traps as well.

TfL specifies a "matt crackle" finish, which is a very slightly rough finish. Apparently it helps those who have a weak grip, such as arthritis sufferers.

That was the intention of the dimpled ones, but unfortunately they were a bit too robust!

 

[Bornin1980s]

Time was when nearly all single deckers with underfloor/underfloor rear engines used horizontally mounted engines, but I don't think any manufacturer uses them now, they all use vertical engines. Why?

 

[GusB]

Time was when nearly all single deckers with underfloor/underfloor rear engines used horizontally mounted engines, but I don't think any manufacturer uses them now, they all use vertical engines. Why?

In mid-engined chassis, horizontal engines were usually necessary in order to keep the floor level as low as possible*. It worked for Volvo with the B10M - it enabled the same chassis to be employed on single- and double-deck service buses, a well as coach applications.

* Not always the case - Bedford used vertical engines, the Dennis Javelin used a vertical Cummins C-series and the Dennis Lancet used a vertical Perkins V8. In the latter case, the floor level was much higher than on similarly-bodied Leyland Tigers.

Bear in mind that in the Good Old Days, engines were fairly big - 10L or thereabouts. Nowadays, diesel buses tend to have engines that are much smaller in size and can produce a similar amount of power when compared to their larger ancestors. This makes it much easier to install a vertical at the back without having a significant effect on the floor level.

When it comes to coaches, most now have floor levels that are so high that the engine orientation makes no difference.

 

[Russel]

When it comes to coaches, most now have floor levels that are so high that the engine orientation makes no difference.

On that note, given the empty space, when not full of luggage, how are coaches not top heavy?

 

[Flying Snail]

On that note, given the empty space, when not full of luggage, how are coaches not top heavy?

All the heavy mechanical stuff is down low, this weighs more than even a full passenger load.

I never noticed much difference when cornering with a full coach versus an empty one, double deckers on the other hand you can really feel them swaying more when full upstairs.

 

[Bornin1980s]

Are there mechanical benefits to using vertical engines?

 

[K4016td]

mechanical benefits to using vertical engines?

Less vibrations, better oil circulation with a lube pump and tend to take less space, and with ever increasing demand on accomodating particulates filters that's always a plus. The best comparision on what filters do to engine bay sizes would be between tower drive buses where this is seen the best - from Euro II to Euro VI, they've almost doubled.

 

[whoosh]

Surprisingly it has 36 seats, not much less than a 12m single door bus manages in the UK.

Clicking through the pictures in the link in post #101, there is a data table for the vehicle at some sort of motor show. It has two examples of floor plans, and says 25-34 as a seating capacity. That range includes the three and four door versions.

Off-bus ticketing along with boarding at any door, means that buses in Prague are very quick in comparison to the snail's pace that some buses in the UK end up operating at! The best I've seen in the UK was a New Bus for London, when all three doors were in operation - pretty slick, and I think we need that back!

 

[GusB]

On that note, given the empty space, when not full of luggage, how are coaches not top heavy?

The centre of gravity is still low enough to prevent them being too top heavy.

Are there mechanical benefits to using vertical engines?

Less vibrations, better oil circulation with a lube pump and tend to take less space, and with ever increasing demand on accomodating particulates filters that's always a plus. The best comparision on what filters do to engine bay sizes would be between tower drive buses where this is seen the best - from Euro II to Euro VI, they've almost doubled.

As well as any mechanical benefits there are also cost savings to be made by not having to develop a horizontal version, especially if the engines are shared with a company's lorry range.

 

[Bornin1980s]

Why is it that both the Leyland Atlantean and the Daimler Fleetline usually have a distinct separate 'bustle' housing for the engine, but all subsequent double deckers have flat backs?

 

[Trainman40083]

Why is it that both the Leyland Atlantean and the Daimler Fleetline usually have a distinct separate 'bustle' housing for the engine, but all subsequent double deckers have flat backs?

Maybe it made them easier to keep clean.

 

[Leyland Bus]

Why is it that both the Leyland Atlantean and the Daimler Fleetline usually have a distinct separate 'bustle' housing for the engine, but all subsequent double deckers have flat backs?

The idea back then was "ease of maintenance" and when the likes of Leyland were pioneering rear engined design, they were trying to persuade operators who were buying and happy with half cabs, which were easy to maintain.

You can open the bonnet and remove the pods on both buses and get at pretty much every component fairly easily.

As the years went on, design and technology evolved, along with stricter rules on noise pollution. So having fully enclosed engine bays and engines hung on struts rather than sat on the chassis all helped to reduce noise and vibration.

 

[Bornin1980s]

Hung on struts?

 

[Leyland Bus]

Hung on struts?

Yeah, essentially two large, thick metal poles hanging down from the upper framework and cushioned by big rubber mountings (that look like big rubber doughnuts!)

I'll try and dig out a picture for you

== Doublepost prevention - post automatically merged: 13 Dec 2024 ==

Hung on struts?

Found one! See photo attached


"Image attached shows the rear of a Leyland Olympian minus its bonnet and shows clearly the struts that the engine hangs from on this type of vehicle."

 

[PG]

Interesting to see the details provided by @Leyland Bus , I never realised that the Olympian had the engine hung from above.
Don't know if older designs of rear engined deckers were similar?

It appears that originally the Atlantean engine bay was envisaged as being enclosed. See these pictures which appeared in Commercial Motor back in 1956.

Images show side and back of prototype rear engined double decker bus.

 

[Leyland Bus]

Interesting to see the details provided by @Leyland Bus , I never realised that the Olympian had the engine hung from above.
Don't know if older designs of rear engined deckers were similar?

It appears that originally the Atlantean engine bay was envisaged as being enclosed. See these pictures which appeared in Commercial Motor back in 1956.
View attachment 170991View attachment 170992

Note the very Bristol VR look in that early sketch. Again, access was deemed more important and that exhaust really wasn't practical was it!

From memory, the MCW Metrobus engines were also hung in a similar (less sturdy! Lol!) way.

 

[GusB]

Interesting to see the details provided by @Leyland Bus , I never realised that the Olympian had the engine hung from above.
Don't know if older designs of rear engined deckers were similar?

It appears that originally the Atlantean engine bay was envisaged as being enclosed. See these pictures which appeared in Commercial Motor back in 1956.

If I recall correctly, one of the issues with the Atlantean prototype was the noise inside the lower saloon, hence the move to having the engine "outside" for the production model.

 

[Bornin1980s]

If I recall correctly, one of the issues with the Atlantean prototype was the noise inside the lower saloon, hence the move to having the engine "outside" for the production model.

What about having the engine 'outside' compared to the later system,'inside' but suspended?

 

[PG]

If I recall correctly, one of the issues with the Atlantean prototype was the noise inside the lower saloon, hence the move to having the engine "outside" for the production model.

I believe that was indeed one of the issues. Seems somewhat ironic that one of the reasons that production of the Atlantean eventually ceased in 1984 was due to it not meeting forthcoming noise legislation.

 

[Bornin1980s]

I believe that was indeed one of the issues. Seems somewhat ironic that one of the reasons that production of the Atlantean eventually ceased in 1984 was due to it not meeting forthcoming noise legislation.

Is that external on internal noise? In any case, I didn't know of noise regulations for road vehicles?

 

[PG]

Is that external on internal noise? In any case, I didn't know of noise regulations for road vehicles?

External noise.
If you wish to delve further into this subject I suggest perusing the The Road Vehicles (Construction and Use) Regulations 1986 which contains a specific clause relating to the Atlantean.

55.
(2)This regulation does not apply to—
(g)a vehicle manufactured by Leyland Vehicles Ltd. and known as the Atlantean Bus, if first used before 1st October 1984.

 

[Taunton]

Are there mechanical benefits to using vertical engines?

The Modernisation Plan dmus used the same horizontal engines as had been developed for buses at around the same time for single-decked buses, it's interesting to contemplate what the railway might have done if the road transport industry had not come up with this variant. In fact horizontal engines are a considerable mechanical nuisance, starting off with where do you locate the oil sump, which thanks to Sir Isaac Newton's Gravity, always needs to be at the bottom of the engine, whichever way it is oriented.

Then such engines are oriented this way to fit, quite tightly, under a floor. This makes engineering access a real nuisance, as instead of working comfortably from the top the fitter has to lie working sideways. Also, working in such a confined area, cooling is difficult to arrange and probably ends up being designed for the minimum you can get away with. The old Volkswagen Beetle car with a flat, horizontally-opposed engine, was air cooled, a second-best option, because conventional water cooling would have been impossible. There must be some figures for maintenance cost differences for the same basic engine between horizontal and vertical.

In passing, designing the lubrication for the Deltic engine must have been a real challenge.

 

[GusB]

Is that external on internal noise? In any case, I didn't know of noise regulations for road vehicles?

External noise.
If you wish to delve further into this subject I suggest perusing the The Road Vehicles (Construction and Use) Regulations 1986 which contains a specific clause relating to the Atlantean.

It was due to external noise. Doug Jack wrote in "Beyond Reality. Leyland Bus - the twighlight years":

The Altantean carried on longer, boosted in part by substantial orders from Iran, Iraq, Singapore and Indonesia. It was known, however, that it would not meet new European legislation on engine noise, to take effect on vehicles first registered on or after 1 April 1983. A twelve month dispensation was granted, partly to help bodybuilders with their production backlog. Future double-deck policy had to rely on the Titan and Olympian.

== Doublepost prevention - post automatically merged: 14 Dec 2024 ==

In fact horizontal engines are a considerable mechanical nuisance, starting off with where do you locate the oil sump, which thanks to Sir Isaac Newton's Gravity, always needs to be at the bottom of the engine, whichever way it is oriented.

Then such engines are oriented this way to fit, quite tightly, under a floor. This makes engineering access a real nuisance, as instead of working comfortably from the top the fitter has to lie working sideways.

This is one of the reasons for the Ailsa being quite popular; it took the front, vertical-engined layout that was commonplace for years and combined it with a front entrance (as opposed to a forward entrance) that permitted one-person operation. It allowed a straight driveline without the complexity of a rear-mounted, transverse engine with all the angle-drives and other gubbins that went along with rear-engined double deckers.

== Doublepost prevention - post automatically merged: 14 Dec 2024 ==

What about having the engine 'outside' compared to the later system,'inside' but suspended?

Sorry, I missed this post. In all honesty, I don't really know. Bristol VRs weren't immune from the "bustle" effect, though - see this photo:

WMPTE 4714 (JOV714P) Bristol VR with MCW body

Seen at SYPTE's Leicester Avenue depot in Doncaster (at a Depot open day).

www.flickr.com

 

[Goldfish62]

It's a shame that when work was done for the VRT Series 3 to reduce external noise that the interior was forgotten. A thin piece of hardboard between the engine compartment and the lower deck saloon isn't the most effective sound insulation.

 

[Ghostbus]

In the provinces, it's not about fare evasion. It is, as @GusB states, that dual door buses cost more to purchase, they cost more to maintain, they lose seated capacity (which is important as average journey duration is longer) and especially when those on the bottom deck are more likely to be elderly.

Now amazingly enough, bus managers are actually aware of buses with dual doors. I'm sure they may even have travelled on some. However, they will also have done the maths and worked out that for the relatively limited benefit on a select number of routes in provincial cities, any benefit is outweighed by the downsides.

Have they done the maths though, really? In the larger busier provincial networks, both urban an inter-urban.

Take a look at Lothian, ever the pioneer. Turns out that for crush loaded routes, with longer legal vehicle lengths the decision to have one or two doors (or even three axles) is now largely an irrelevance to the more important variables of overall length and staff costs. A 100 seat dual door triaxle seems to bring greater benefits than simply adding a door. Smoothing out and indeed lowering the vehicle requirement is the apparent aimed for benefit of that extra capacity and its necessary extra door, rather than increasing boarding speed or overall journey times.

They could have gone for triple doors and even a tram style lower salloon on such big buses, if they had wanted to speed up boarding and thus maintain frequencies and have faster journey times. But why would they? That just means you have to buy more buses, have bigger depots and employ more drivers. And then you're stuck with an even more unusual bus that would have no real value on the second hand market, and cost even more to convert to a single door school bus.

Turns out that a single driver sitting on a very long bus in a bus lane doing largely nothing in long-ish dwell times, but doing it on a basic wage and standard shift pattern as part of a centrally planned city bus network, is a quite economical way of achieving capacity improvements. As is presumably moving large volumes of fresh air in large heavy vehicles on polluted congested streets outside the peak. Not ideal, but far better than the alternatives.

One wonders then, why the benefits of longer double decker buses hasn't also been realised by management in other cities. London is probably too hamstring by the bureaucracy of tendering and the hangovers from artics to be so innovative. But for cities like Reading, which are near or at crush loading on their core routes, but which will never be suitable for trams or tram like buses, it's probably an ideal solution. Especially where you already own your own fleet and directly employ your drivers. Might even be a great incentive for some councils to kick out the big groups and independents and start their own bus company.

 

[Pyewipecarshed]

It's a shame that when work was done for the VRT Series 3 to reduce external noise that the interior was forgotten. A thin piece of hardboard between the engine compartment and the lower deck saloon isn't the most effective sound insulation.

I believe when new they had a layer of soundproofing material as well as the hardboard. However fitters tended to remove it and not put it back.

 

[GusB]

Have they done the maths though, really? In the larger busier provincial networks, both urban an inter-urban.

Take a look at Lothian, ever the pioneer. Turns out that for crush loaded routes, with longer legal vehicle lengths the decision to have one or two doors (or even three axles) is now largely an irrelevance to the more important variables of overall length and staff costs. A 100 seat dual door triaxle seems to bring greater benefits than simply adding a door. Smoothing out and indeed lowering the vehicle requirement is the apparent aimed for benefit of that extra capacity and its necessary extra door, rather than increasing boarding speed or overall journey times.

They could have gone for triple doors and even a tram style lower salloon on such big buses, if they had wanted to speed up boarding and thus maintain frequencies and have faster journey times. But why would they? That just means you have to buy more buses, have bigger depots and employ more drivers. And then you're stuck with an even more unusual bus that would have no real value on the second hand market, and cost even more to convert to a single door school bus.

Turns out that a single driver sitting on a very long bus in a bus lane doing largely nothing in long-ish dwell times, but doing it on a basic wage and standard shift pattern as part of a centrally planned city bus network, is a quite economical way of achieving capacity improvements. As is presumably moving large volumes of fresh air in large heavy vehicles on polluted congested streets outside the peak. Not ideal, but far better than the alternatives.

One wonders then, why the benefits of longer double decker buses hasn't also been realised by management in other cities. London is probably too hamstring by the bureaucracy of tendering and the hangovers from artics to be so innovative. But for cities like Reading, which are near or at crush loading on their core routes, but which will never be suitable for trams or tram like buses, it's probably an ideal solution. Especially where you already own your own fleet and directly employ your drivers. Might even be a great incentive for some councils to kick out the big groups and independents and start their own bus company.

Eh?

== Doublepost prevention - post automatically merged: 15 Dec 2024 ==

It's a shame that when work was done for the VRT Series 3 to reduce external noise that the interior was forgotten. A thin piece of hardboard between the engine compartment and the lower deck saloon isn't the most effective sound insulation.

I've only ever experienced travelling on a Bristol VRT once. It was one of a few that had been transferred north from East Midland and I think it would be fair to say that it was "end of life" when it arrived! That said, it was no worse than the Fleetlines that had disappeared a few years earlier.

 

[Goldfish62]

On the multi-door debate it was interesting that on LinkedIn recently none other than Bob Montgomery, former MD of Stagecoach UK Bus and now an independent consultant remarked that urban bus design in the UK has gone backwards since the 70s, from dual door to single door design.

I also think that the argument that many bus stations only allow front door boarding so dual door buses aren't practical is a red herring. The wheelchair ramp doesn't have to be at the middle door. It can be at the front, and on such bus stations you simply load and unload at the front door, with most journeys either starting or terminating in such bays. I know it works because I've experienced it in Bath with First's dual door buses.

 

[MotCO]

I've never understood why some Ford Transit minibuses had dual doors!

 

[Goldfish62]

I've never understood why some Ford Transit minibuses had dual doors!

I can see a certain logic in it. These van conversions were incredibly cramped internally with next to no chance of getting past other standing passengers unless they got off the bus to let you off. It could help on busy urban routes with a high churn of passengers.