Lorry design

Kieran_Burns
Kieran_Burns Posts: 9,757
edited July 2013 in Commuting chat
Could someone explain to me why lorries / coaches can't have the cab at 'ground' level rather than 6' up in air?

(decided to start a new thread so as not derail other condolence ones....)

Mount the engine behind the cab and have the radiator above it. It can't be because of vehicle height concerns or we'd have no double-decker buses.
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Comments

  • dhope
    dhope Posts: 6,699
    Would imagine that as they're dragging a box the length of a house around then they need to be able to see over the top of cars so they can see where it's going in the mirrors if they need to manoeuvre slowly.
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  • CiB
    CiB Posts: 6,098
    edited April 2013
    It's because its wheels are 4 foot in diameter not 16" with rubber band tyres, and the engine tends to be under the cab to make maximum use of the space where the engine isn't, so the driver ends up sitting over the engine, which is a multi-litre affair not a 1200cc revomatic so is a lot bigger. Same reason tractors are tall - big wheels, big engine that the driver sits behind, at a higher level.
  • rick_chasey
    rick_chasey Posts: 74,740
    Some bin lorries do it already.
  • herb71
    herb71 Posts: 253
    Most of our trucks now have a cab over engine, which minimises the length of the tractor unit, hence maximising the carrying capacity within a given length of vehicle.

    Design of HGV has evolved over decades, and in part has evolved they way they have due to legislation maximising vehicle length and certain other parameters.

    Starting with a clean sheet, there is no reason why the tractor unit couldn't look different, with the driver at eye level with the rest of the traffic. Think about the tractor units used to shuffle planes around which are designed to a different set of parameters. The design would be compromised in other areas, which may mean a loss of capacity / load efficiency.

    The only way things will significantly change is if legislation forces it.
  • rubertoe
    rubertoe Posts: 3,994
    As do some coaches.
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  • danlikesbikes
    danlikesbikes Posts: 3,898
    I mentioned it in another thread a while ago now. Seems to be an easy fix for garbage/waste trucks who need maximum visibility to manoeuvre & I guess also not crush their own employees.

    Just found my old thread viewtopic.php?f=40013&t=12911992&hilit=Campaigners+in+lorry+redesign+call#p18212691

    The link was to a BBC report which if you excuse the graphic as being a bit tonka toy like show how the windows could be lowered to allow much greater views for the driver but keep the same height for the cab as assume this has quite some aero effect on the trailer.
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  • veronese68
    veronese68 Posts: 27,567
    As Rick said many bin lorries do already. I think Herb is right in that it needs legislation to force a change, otherwise it will be seen as an unnecessary expense. What about this?
  • davis
    davis Posts: 2,506
    dhope wrote:
    Would imagine that as they're dragging a box the length of a house around then they need to be able to see over the top of cars so they can see where it's going in the mirrors if they need to manoeuvre slowly.

    That argument doesn't work if you e.g. replace the "cars" in your sentence with "other lorries" or "buildings"....
    I.e. lorries often have to manoeuvre in places where the extra height doesn't allow them to see any more than if they were low down...
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  • Ben6899
    Ben6899 Posts: 9,686
    Veronese68 wrote:
    As Rick said many bin lorries do already. I think Herb is right in that it needs legislation to force a change, otherwise it will be seen as an unnecessary expense. What about this?

    That's what's in the BBC graphic.
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  • Kieran_Burns
    Kieran_Burns Posts: 9,757
    I was just wondering if there was some way of moving the motive power to the trailer.... but I keep hitting obstacles.
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  • jedster
    jedster Posts: 1,717
    Most of our trucks now have a cab over engine, which minimises the length of the tractor unit, hence maximising the carrying capacity within a given length of vehicle.

    This.

    And of course maximum load capacity per truck is more economically and environmentally efficient.

    Of course this is more of an issue for big tractor trailer rigs but some of the designs are modular so cabs are carried over to shorter rigids. Again, would be higher cost without the economies of scale. Also manouvreability would suffer from extra length
  • davmaggs
    davmaggs Posts: 1,008
    Veronese68 wrote:
    As Rick said many bin lorries do already. I think Herb is right in that it needs legislation to force a change, otherwise it will be seen as an unnecessary expense. What about this?

    Where is the engine in that graphic?

    What these BR debates virtually always lack is knowledge of driving lorries, and more importantly how the mechanics of them actually work (e.g why they are laid out the way that they are).

    By mechanics I mean, why are cabs of trucks designed as they are in many different truck building countries who could have chosen to build them differently? Could it be because items like steering wheels need to physically be placed in certain places, because wheel diameters relate to ability to pull load. I've no idea of the answers, but I suspect it really isn't as simply as lowering some windows and sticking the driver down at car level.
  • mbthegreat
    mbthegreat Posts: 179
    I've got it: Put the engine ON TOP of the cab.

    I see no problems with this plan.
  • mudcow007
    mudcow007 Posts: 3,861
    should really count it as lucky we don't use more bull nosed units (American stylee with their engines in front of the driver)

    there has recently been a rise in bull nosed scania's in Liverpool, i think its an irish haulier.

    with the engine being completely in front of the cable drivers vision must be reduced and.....they have an even smaller turning circle than traditional units as their cab is longer

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  • jedster
    jedster Posts: 1,717
    bull nose designs are cheaper (actually more difficult to put the cab over the engine) but have the drawbacks on visibility you mention plus length (- load capacity). US trucks are typically bull nose because they dont have the same length resytrictions (roads bigger, wider, less windy)
  • The Rookie
    The Rookie Posts: 27,812
    mudcow007 wrote:
    .....they have an even BIGGer turning circle than traditional units as their cab is longer
    FTFY

    Changing the design of trucks where the same basic design is used world wide will come up against a lot of hurdles, the change would have to be agreed world wide and you probably couldn't pahse it in for new trucks for at least 5 years.....world wide the downsides are likley to outweigh the benfits, so instead lets look at making what we have safer perhaps.
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  • Big_Paul
    Big_Paul Posts: 277
    I mentioned it in another thread a while ago now. Seems to be an easy fix for garbage/waste trucks who need maximum visibility to manoeuvre & I guess also not crush their own employees.

    Just found my old thread viewtopic.php?f=40013&t=12911992&hilit=Campaigners+in+lorry+redesign+call#p18212691

    The link was to a BBC report which if you excuse the graphic as being a bit tonka toy like show how the windows could be lowered to allow much greater views for the driver but keep the same height for the cab as assume this has quite some aero effect on the trailer.

    Bin lorries, for all their size, use small, low powered engines, and are more like a bus, most truck makers tend to use a single design, dictated by the size of the engine, most lorry engines are bloody huge, as a smaller engine, believe it or not is less economical than a big one when they're loaded as they are screaming along in lower gears. Volvo already have tried low cabs, that's what the FL was, now they have the FH and FM, you're more likely to see an FM in town as they are preferred for rigids, as it's a lower cab.

    If you banned lorries from towns, you're going to have 6 or 8 white van men for every lorry you take out. 6 or 8 minimum wages so costs will rise, 6 or 8 potential accidents.
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  • danlikesbikes
    danlikesbikes Posts: 3,898
    Big_Paul wrote:

    Bin lorries, for all their size, use small, low powered engines, and are more like a bus, most truck makers tend to use a single design, dictated by the size of the engine, most lorry engines are bloody huge, as a smaller engine, believe it or not is less economical than a big one when they're loaded as they are screaming along in lower gears. Volvo already have tried low cabs, that's what the FL was, now they have the FH and FM, you're more likely to see an FM in town as they are preferred for rigids, as it's a lower cab.

    If you banned lorries from towns, you're going to have 6 or 8 white van men for every lorry you take out. 6 or 8 minimum wages so costs will rise, 6 or 8 potential accidents.

    It as very good point & had considered the lower engine need of a bin lorry as possibly being an issue.

    However (no expert on trucks so please bear with me) in a modern lorry does the engine not sit underneath the cab. Like the tilt front type of commercial truck excluding the bull nose type ones. If so the where the drivers feet/knees are apart from the dash with its electronics what else is there?

    If its electrical items then surly we could move these to the rear of the cab, or situate them above where the driver sits. That way we could lower the dash and allow for an increased front window & also lower the side windows (guess would have to be split) to allow better all-round view for the driver.

    Just an idea but trying to come up with a practical option which is what I think the campaign is looking to do.
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  • Big_Paul
    Big_Paul Posts: 277
    Radiator for a start, they are massive, there's an awful lot of the electrical gubbins in there too for easy access, the really low bin lorries use the cab sitting almost ahead of the engine or the engine sits up in the middle of the cab, you can't really lower the dash as it's really not any higher than a car one, if anything the dash is lower so you don't have as big a blind spot. The newer buses work well because the engine is at the very back and is turned sideways driving a transverse gearbox, but a lorry will always be dictated by the engine and the need for a habitable cab for distance work.
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  • danlikesbikes
    danlikesbikes Posts: 3,898
    Big_Paul wrote:
    Radiator for a start, they are massive, there's an awful lot of the electrical gubbins in there too for easy access, the really low bin lorries use the cab sitting almost ahead of the engine or the engine sits up in the middle of the cab, you can't really lower the dash as it's really not any higher than a car one, if anything the dash is lower so you don't have as big a blind spot. The newer buses work well because the engine is at the very back and is turned sideways driving a transverse gearbox, but a lorry will always be dictated by the engine and the need for a habitable cab for distance work.

    See where you coming from then, guess its either back to the drawing board or looking at some sort of retro fit to existing vehicles. Which perhaps might make more sense as these could be added to new vehicles thereby bringing down the cost.
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  • redvee
    redvee Posts: 11,922
    In the mid 80's, to maximise deck length on drawbar rigids a design called "Phillips Concept" was used where the sleeper was above the cab and slim.

    http://www.commercialmotor.com/big-lorr ... WdQsaKsiSo
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  • kelsen
    kelsen Posts: 2,003
    Somebody in the EC has been reading Commuting Chat!

    http://www.bbc.co.uk/news/business-23152918
  • Big_Paul
    Big_Paul Posts: 277
    kelsen wrote:
    Somebody in the EC has been reading Commuting Chat!

    http://www.bbc.co.uk/news/business-23152918

    Reading between the lines it's primarily to do with aerodynamics meaning a cruising lorry can pass stricter emissions tests, any safety to third parties is a welcome side effect.

    You still see over cab sleepers, a lot of removal wagons have them, but they're not nice to get into and it's rather like sleeping in a coffin.
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