TerraLiner:12 m Globally Mobile Beach House/Class-A Crossover w 6x6 Hybrid Drivetrain
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8. A Few Contemporary MAN Trucks with Tandem Axles in Front
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So the tandem-axles-up-front configuration of the old 6x6 Tatra 813's, or the new Kamaz Typhoon, is to say the least very unusual.
On the web, the only other vehicles that I could find that are even remotely similar, are some MAN 6x6 trucks that have a large crane mounted between the cab and the loading box -- see http://www.ditzj.de/html/en/trucks/man/verk6x6.html :
In effect, this is an 8x8 MAN FE 460 A "tipper" truck, but with the fourth axle cut off. Or as egn once described things, it looks like a "castrated" 8x8:
However, note the 6x6s with cranes shown above were not originally 8x8's. Rather, they were built as 6x6's directly at the factory.
According to the website:
So here again, we encounter the idea that having a double front axle improves stability, traction, steering, and handling, especially on winding, "bendy unpaved roads in the mountains". These are exactly the kinds of roads that overlanders love to explore. And as a "bad-road-capable" vehicle, these are exactly the kinds of roads that the TerraLiner should be able to handle with ease. Again, see http://www.ditzj.de/html/en/trucks/man/verk6x6.html .
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8. A Few Contemporary MAN Trucks with Tandem Axles in Front
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So the tandem-axles-up-front configuration of the old 6x6 Tatra 813's, or the new Kamaz Typhoon, is to say the least very unusual.
On the web, the only other vehicles that I could find that are even remotely similar, are some MAN 6x6 trucks that have a large crane mounted between the cab and the loading box -- see http://www.ditzj.de/html/en/trucks/man/verk6x6.html :
In effect, this is an 8x8 MAN FE 460 A "tipper" truck, but with the fourth axle cut off. Or as egn once described things, it looks like a "castrated" 8x8:
However, note the 6x6s with cranes shown above were not originally 8x8's. Rather, they were built as 6x6's directly at the factory.
According to the website:
So here again, we encounter the idea that having a double front axle improves stability, traction, steering, and handling, especially on winding, "bendy unpaved roads in the mountains". These are exactly the kinds of roads that overlanders love to explore. And as a "bad-road-capable" vehicle, these are exactly the kinds of roads that the TerraLiner should be able to handle with ease. Again, see http://www.ditzj.de/html/en/trucks/man/verk6x6.html .
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9. The Kamaz Typhoon's Tandem Axles in Front: Weight Distribution?
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According to “Military Today”, the primary motivation for the tandem-axles-in-front configuration in the Typhoon was weight distribution:
See http://www.military-today.com/apc/kamaz_taifun.htm .
In the case of all-purpose "generalist" 6x6 military transports like the MAN HX-58, the tandem axles need to be at the back of the vehicle, in order to support the potentially heavy weight of certain kinds of cargo:
Below is an excellent video of the HX-58, a video that was not available 6 months ago, when I first posted extensively about the MAN HX-series:
This sort of general-purpose military transport might carry heavy boxes of ammunition one day, food supplies the next, and infantry the day after that.
The Kamaz Typhoon, on the other hand, is a dedicated troop-carrier, full stop. So the Typhoon doesn't need the tandem axles in back to support potentially heavy cargo. Ergo, Kamaz had more of a free hand to place the Typhoon's axles where they might prove "optimal" for other reasons.
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10. Why "cargo flexibility" and "axle-load distribution" matter a bit less for the TerraLiner
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In this sense the Typhoon is a more telling precedent for the TerraLiner than the MAN 6x6 HX-58 and/or SX-44, because the Typhoon's "standard operating procedure" is to travel as a box that is mostly empty air, with the predictable weight of a complement of infantry. And just like the Typhoon, the TerraLiner will travel as a box filled mostly with empty air: it will be a motorhome, not a delivery truck.
With that said, however, it's also true that in the case of the Terraliner, optimizing weight distribution by playing with the axle-placement matters a bit less, now that everyone has agreed that the TerraLiner will be a diesel-electric serial-hybrid vehicle. Getting the front-to-rear weight balance right is slightly less of a hassle for a hybrid diesel-electric, because the various pieces of the drive train (diesel motor, generator, batteries, electric motors) can be distributed throughout the vehicle so as to optimize front/back balance, and axle loads.
At present my team has been designing the TerraLiner with two Steyer/Jenoptik 120 KW diesel generators, sitting on trays that slide out "width-wise", located on the sides of the frame between the single axle and the tandem axles – seehttp://www.jenoptik.com/en_30134_auxiliary_power_units, http://www.jenoptik.com/en_40173_adsf263 , http://www.jenoptik.com/cms/product...BD728/$File/esw_euro5_apu_120kw_2012.pdf?Open , and http://www.jenoptik.com/cms/jenopti...ems_2012.pdf/$file/ESW_EnergySystems_2012.pdf , as well as post #673 on page 68 , and posts #1236 and #1237 on page 124, at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page68 and http://www.expeditionportal.com/for...edition-RV-w-Rigid-Torsion-Free-Frame/page124 .
And we've been designing for a rather conventional, one axle forward, and two axles in back configuration.
However, if there are some good additional reasons why two axles forward should be preferred, I am willing to consider changing the TerraLiner's axle layout. I suspect there might be, hence my keen interest in this topic: my keen interest in finding out exactly why Kamaz located the axles on the Typhoon where it did.
Yes, it's a bit foolish of me to not have considered this issue at length before. I have to admit that my thinking about TerraLiner axle-placement was still running along lines that were too "conventional". After all, almost every 6x6 currently in production, whether military or civilian, has the tandem axles located at the back of the vehicle. So it seemed that there must be good reasons why manufacturers have standardized on this arrangement. But then along came Thjakits with his post about the Typhoon, and suddenly I realized that perhaps the "conventional wisdom" is just that: merely conventional.
If Oshkosh, MAN, Tatra, et al, design their 6x6s with the tandem axles in back only because they need operational flexibility, i.e. cargo flexibility -- troops one day, heavy ammunition the next -- then this line of reasoning simply does not apply to the TerraLiner. If that's the main reason, and perhaps the only good reason, to prefer the more conventional axle configuration, then the conventional configuration should be scrapped. Especially if there are additional reasons why the Typhoon's tandem axles up-front configuration could be considered superior.
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9. The Kamaz Typhoon's Tandem Axles in Front: Weight Distribution?
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According to “Military Today”, the primary motivation for the tandem-axles-in-front configuration in the Typhoon was weight distribution:
See http://www.military-today.com/apc/kamaz_taifun.htm .
In the case of all-purpose "generalist" 6x6 military transports like the MAN HX-58, the tandem axles need to be at the back of the vehicle, in order to support the potentially heavy weight of certain kinds of cargo:
Below is an excellent video of the HX-58, a video that was not available 6 months ago, when I first posted extensively about the MAN HX-series:
This sort of general-purpose military transport might carry heavy boxes of ammunition one day, food supplies the next, and infantry the day after that.
The Kamaz Typhoon, on the other hand, is a dedicated troop-carrier, full stop. So the Typhoon doesn't need the tandem axles in back to support potentially heavy cargo. Ergo, Kamaz had more of a free hand to place the Typhoon's axles where they might prove "optimal" for other reasons.
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10. Why "cargo flexibility" and "axle-load distribution" matter a bit less for the TerraLiner
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In this sense the Typhoon is a more telling precedent for the TerraLiner than the MAN 6x6 HX-58 and/or SX-44, because the Typhoon's "standard operating procedure" is to travel as a box that is mostly empty air, with the predictable weight of a complement of infantry. And just like the Typhoon, the TerraLiner will travel as a box filled mostly with empty air: it will be a motorhome, not a delivery truck.
With that said, however, it's also true that in the case of the Terraliner, optimizing weight distribution by playing with the axle-placement matters a bit less, now that everyone has agreed that the TerraLiner will be a diesel-electric serial-hybrid vehicle. Getting the front-to-rear weight balance right is slightly less of a hassle for a hybrid diesel-electric, because the various pieces of the drive train (diesel motor, generator, batteries, electric motors) can be distributed throughout the vehicle so as to optimize front/back balance, and axle loads.
At present my team has been designing the TerraLiner with two Steyer/Jenoptik 120 KW diesel generators, sitting on trays that slide out "width-wise", located on the sides of the frame between the single axle and the tandem axles – seehttp://www.jenoptik.com/en_30134_auxiliary_power_units, http://www.jenoptik.com/en_40173_adsf263 , http://www.jenoptik.com/cms/product...BD728/$File/esw_euro5_apu_120kw_2012.pdf?Open , and http://www.jenoptik.com/cms/jenopti...ems_2012.pdf/$file/ESW_EnergySystems_2012.pdf , as well as post #673 on page 68 , and posts #1236 and #1237 on page 124, at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page68 and http://www.expeditionportal.com/for...edition-RV-w-Rigid-Torsion-Free-Frame/page124 .
And we've been designing for a rather conventional, one axle forward, and two axles in back configuration.
However, if there are some good additional reasons why two axles forward should be preferred, I am willing to consider changing the TerraLiner's axle layout. I suspect there might be, hence my keen interest in this topic: my keen interest in finding out exactly why Kamaz located the axles on the Typhoon where it did.
Yes, it's a bit foolish of me to not have considered this issue at length before. I have to admit that my thinking about TerraLiner axle-placement was still running along lines that were too "conventional". After all, almost every 6x6 currently in production, whether military or civilian, has the tandem axles located at the back of the vehicle. So it seemed that there must be good reasons why manufacturers have standardized on this arrangement. But then along came Thjakits with his post about the Typhoon, and suddenly I realized that perhaps the "conventional wisdom" is just that: merely conventional.
If Oshkosh, MAN, Tatra, et al, design their 6x6s with the tandem axles in back only because they need operational flexibility, i.e. cargo flexibility -- troops one day, heavy ammunition the next -- then this line of reasoning simply does not apply to the TerraLiner. If that's the main reason, and perhaps the only good reason, to prefer the more conventional axle configuration, then the conventional configuration should be scrapped. Especially if there are additional reasons why the Typhoon's tandem axles up-front configuration could be considered superior.
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11. The Kamaz Typhoon's Tandem Axles in Front: Turning Radius? Bootleg Turns?
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For instance, optimal weight-distribution may not be the only reason for the Typhoon’s unusual arrangement of axles.
The Typhoon is advertised as having a turning radius of less than 10 m, or just a bit more than its own length. Haf-E and egn have already suggested that this seems an automatic benefit of having two steerable axles up front:
But is a turning radius of 10 m for a vehicle that’s 8 or 9 m long, really that impressive? Tatra’s more conventionally configured 6x6’s (one axle in front, two in back), of comparable length (7.8 to 9.0 m), all have turning radiuses that are no worse.
In its product literature, Tatra expresses this figure in terms of diameter, rather than radius. So in the following PDFs one needs to divide the stated number for the turning circle by half: see http://www.tatratrucks.com/about-the-company/gallery/brochures/ , http://www.tatratrucks.com/underwood/download/files/tatra-t815-7l0r39-6x6_cargo-truck.pdf , http://www.tatratrucks.com/underwood/download/files/tatra-t815-790rk9-6x6-chassis_en.pdf , http://www.tatratrucks.com/underwood/download/files/tatra-t810-1r0r26-6x6-cargo-carrier_en.pdf , http://www.tatratrucks.com/underwood/download/files/tatra-t810-1r0r26-6x6-load-handling-unit_en.pdf , http://www.tatratrucks.com/underwoo...hoenix-t158-8pr33-6x6-cargo-carrier-e3_en.pdf , http://www.tatratrucks.com/underwoo...oenix-t158-8p3n36-6x6-semitrailer-tractor.pdf , and http://www.tatra.cz/underwood/download/files/tatra-military-vehicles_en.pdf (in the catalog, see pages 32 - 33 and 44 – 47 for the most relevant comparisons).
With that said, however, egn’s qualification “very tight turns on loose ground, because traction follows the steering wheel” may illuminate the critical difference.
Even though The Typhoon’s "official" turning radius is no better than Tatra 6x6s of similar length, perhaps even still the Typhoon can turn much tighter on loose ground at high speed, as demonstrated in some of the videos where the Typhoon does a “bootleg turn” on snow – see http://en.wikipedia.org/wiki/Bootleg_turn :
[video=vimeo;63172012]https://vimeo.com/63172012[/video]
The way the Typhoon whips around on snow, you'd think that Burt Reynolds is driving it!...:smiley_drive: In the video below, exactly 6 minutes and 20 seconds in, you can see the Typhoon pull off its "bootleg turn" in slow motion, fishtailing the whole way......
I then wonder if the Typhoon might also be able to pull off a J-turn – see http://en.wikipedia.org/wiki/J-turn :wings: :
With its first two axles towards the front, the Typhoon seems to have the natural ability to do a controlled "fish-tail" turn, with its rear end swinging around much more easily than a MAN HX-58 or SX-44.
So I wonder whether the designers at Kamaz had this explicitly in mind right from the beginning, when they first began designing the Typhoon? Were they hanging out at Tatra 813 6x6 truck trials in the Czech Republic, fantasizing about a dedicated troop carrier that could pull off similar bootleg turns?
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11. The Kamaz Typhoon's Tandem Axles in Front: Turning Radius? Bootleg Turns?
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For instance, optimal weight-distribution may not be the only reason for the Typhoon’s unusual arrangement of axles.
The Typhoon is advertised as having a turning radius of less than 10 m, or just a bit more than its own length. Haf-E and egn have already suggested that this seems an automatic benefit of having two steerable axles up front:
But is a turning radius of 10 m for a vehicle that’s 8 or 9 m long, really that impressive? Tatra’s more conventionally configured 6x6’s (one axle in front, two in back), of comparable length (7.8 to 9.0 m), all have turning radiuses that are no worse.
In its product literature, Tatra expresses this figure in terms of diameter, rather than radius. So in the following PDFs one needs to divide the stated number for the turning circle by half: see http://www.tatratrucks.com/about-the-company/gallery/brochures/ , http://www.tatratrucks.com/underwood/download/files/tatra-t815-7l0r39-6x6_cargo-truck.pdf , http://www.tatratrucks.com/underwood/download/files/tatra-t815-790rk9-6x6-chassis_en.pdf , http://www.tatratrucks.com/underwood/download/files/tatra-t810-1r0r26-6x6-cargo-carrier_en.pdf , http://www.tatratrucks.com/underwood/download/files/tatra-t810-1r0r26-6x6-load-handling-unit_en.pdf , http://www.tatratrucks.com/underwoo...hoenix-t158-8pr33-6x6-cargo-carrier-e3_en.pdf , http://www.tatratrucks.com/underwoo...oenix-t158-8p3n36-6x6-semitrailer-tractor.pdf , and http://www.tatra.cz/underwood/download/files/tatra-military-vehicles_en.pdf (in the catalog, see pages 32 - 33 and 44 – 47 for the most relevant comparisons).
With that said, however, egn’s qualification “very tight turns on loose ground, because traction follows the steering wheel” may illuminate the critical difference.
Even though The Typhoon’s "official" turning radius is no better than Tatra 6x6s of similar length, perhaps even still the Typhoon can turn much tighter on loose ground at high speed, as demonstrated in some of the videos where the Typhoon does a “bootleg turn” on snow – see http://en.wikipedia.org/wiki/Bootleg_turn :
[video=vimeo;63172012]https://vimeo.com/63172012[/video]
The way the Typhoon whips around on snow, you'd think that Burt Reynolds is driving it!...:smiley_drive: In the video below, exactly 6 minutes and 20 seconds in, you can see the Typhoon pull off its "bootleg turn" in slow motion, fishtailing the whole way......
I then wonder if the Typhoon might also be able to pull off a J-turn – see http://en.wikipedia.org/wiki/J-turn :wings: :
With its first two axles towards the front, the Typhoon seems to have the natural ability to do a controlled "fish-tail" turn, with its rear end swinging around much more easily than a MAN HX-58 or SX-44.
So I wonder whether the designers at Kamaz had this explicitly in mind right from the beginning, when they first began designing the Typhoon? Were they hanging out at Tatra 813 6x6 truck trials in the Czech Republic, fantasizing about a dedicated troop carrier that could pull off similar bootleg turns?
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12. The Kamaz Typhoon's Tandem Axles in Front: Trench Crossing?
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Now if the Typhoon’s two axles up front don’t improve the turning radius all that much, then what else might further explain Kamaz’s decision to place them there?
For instance, I wonder whether it’s much easier for a 6x6 to cross certain kinds of trenches when the tandem-axles are forward, instead of in the rear? After all, the tandem-axles-forward configuration seems very strongly preferred for 6x6’s used in truck trials.
Here is what trench-crossing looks like with an Tatra 815 8x8:
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12. The Kamaz Typhoon's Tandem Axles in Front: Trench Crossing?
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Now if the Typhoon’s two axles up front don’t improve the turning radius all that much, then what else might further explain Kamaz’s decision to place them there?
For instance, I wonder whether it’s much easier for a 6x6 to cross certain kinds of trenches when the tandem-axles are forward, instead of in the rear? After all, the tandem-axles-forward configuration seems very strongly preferred for 6x6’s used in truck trials.
Here is what trench-crossing looks like with an Tatra 815 8x8:
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See https://www.youtube.com/watch?v=9D5JNWZQSe8, about 1 minute 45 seconds into the video:
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See https://www.youtube.com/watch?v=9D5JNWZQSe8, about 1 minute 45 seconds into the video:
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And here is what “wide” trench-crossing looks like with a Kamaz “Ural Typhoon”, which has tandem-axles in the rear:
See https://www.youtube.com/watch?v=R6K22coqNsY, about 1 minute 50 seconds into the video:
I could not find an really good equivalent videos of the Typhoon or a Tatra 6x6 with tandem-axles in the front, crossing a trench. The following two videos come close, but they are still not quite what we need in order to understand how trench-crossing would work for a 6x6 with tandem-axles in the front:
None of the Typhoon videos from YouTube that I posted at the beginning of this series shows deep trench or deep ditch crossing. There is a Bulgarian entertainment-sharing website called Vbox7 that has some additional Typhoon clips, but most of the footage merely repeats the stuff shown on YouTube -- see http://en.wikipedia.org/wiki/VBOX7 . The Vbox7 website is incredibly difficult to use, and it's very slow. But if you're willing to take a walk in the Internet wilds of Bulgaria, see http://vbox7.com/play:81c3bb0160 , http://vbox7.com/play:1794295557 , http://vbox7.com/play:590cb3f251 , and http://vbox7.com/play:f431e292 .
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And here is what “wide” trench-crossing looks like with a Kamaz “Ural Typhoon”, which has tandem-axles in the rear:
See https://www.youtube.com/watch?v=R6K22coqNsY, about 1 minute 50 seconds into the video:
I could not find an really good equivalent videos of the Typhoon or a Tatra 6x6 with tandem-axles in the front, crossing a trench. The following two videos come close, but they are still not quite what we need in order to understand how trench-crossing would work for a 6x6 with tandem-axles in the front:
None of the Typhoon videos from YouTube that I posted at the beginning of this series shows deep trench or deep ditch crossing. There is a Bulgarian entertainment-sharing website called Vbox7 that has some additional Typhoon clips, but most of the footage merely repeats the stuff shown on YouTube -- see http://en.wikipedia.org/wiki/VBOX7 . The Vbox7 website is incredibly difficult to use, and it's very slow. But if you're willing to take a walk in the Internet wilds of Bulgaria, see http://vbox7.com/play:81c3bb0160 , http://vbox7.com/play:1794295557 , http://vbox7.com/play:590cb3f251 , and http://vbox7.com/play:f431e292 .
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13. Speculation: How the Kamaz Typhoon Might Cross a Trench
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In the absence of concrete imagery, I would then speculate as follows. Although clearly a tandem-axles up front 6x6 is not going to be able to cross a trench or a ditch as smoothly as the 8x8 Tatra 815 shown above, it still seems possible that it would not be quite as likely to get “stuck”, as a 6x6 whose tandem-axles are located in the rear. Here is my reasoning.
Imagine a normal 6x6 trying to cross the first trench depicted above, as traversed by a Tatra 815 8x8. The minute the first axle of the normal 6x6 hits the trench, it will dive right in, and will get completely stuck. Sure, if the trench is shallow enough and the slopes soft enough, the 6x6 might be able to back up out of the trench, pulling that first axle up and back. But going forward would not be an option.
In the following diagram, the front axle of a standard 6x6 has dropped into the trench, and there is no escaping without recovery assistance:
The website advises: "Winch up the front end of the vehicle until the wheels clear the ditch. Then slowly reverse the vehicle back to solid ground. When safely away from the edge of the ditch, lower the wheels and unhitch your vehicle. If you have no winch, another vehicle may be used for power, though more rigging will be required." See http://www.landyonline.co.za/techtalk/vehicle_recovery.htm .
Note that even if this 6x6 had approached the ditch with considerable momentum and speed, the minute the front axle dropped into the ditch, the vehicle would have come to a shattering stop. All the momentum of the vehicle will have been transferred downwards, at an angle into the ditch.
Now imagine instead that a 6x6 with tandem-axles in front tries to cross the same trench. The first two axles are fine, and would merely duplicate the opening sequence we just saw above for the 8x8 Tatra 815, in post #1372. Once the third axle hits the trench, however, needless to say it drops right in.
However, if the trench is not too deep, then theoretically it seems at least possible that the 6x6 could still move forwards. The first two tandem axles would now be pulling the third axle up and out of the trench. And this might prove even more the case if one tries crossing the trench at considerable speed, with lots of forward momentum. Yes, when the third axle at the back of the vehicle hits the trench and drops down, the "bump" will be incredibly jarring. But with enough forward momentum, and with the rest of the vehicle's mass continuing to go forwards and now angled upwards, there might be enough force to pull the third axle out of the ditch or trench.
Put technically, the lines of force in a 6x6 with tandem axles forward seem to be theoretically more “favorable” to trench-crossing (within limits), than the lines of force in a conventional 6x6. The conventional 6x6 might be able to back up out of a bad “front axle stuck in a trench” situation, but it can't go forward. Whereas a 6x6 with tandem-axles up front wants to go forward, in order to get out of a bad situation in which its trailing single axle gets caught in a trench.
I am just wildly speculating here, so what I just wrote may be completely wrong-headed. If any of you guys have seen Tatra 813 6x6's with tandem-axles placed forward at truck trials, negotiating trenches, and would be willing to offer some practical insight, that would be most helpful indeed. This is a very specialized question, and it's really only those who have some experience either seeing 6x6's in action in truck trials, or better yet, driving such vehicles in truck trials, who would best be able to provide answers.....
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14. Turtling in a 6x6 that has Tandem-Axles up Front
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Just a brief aside: in the first video just posted, notice how the tandem-axles up front do not immunize this 6x6 from “turtling”. It is still just as vulnerable to getting stuck in this way; perhaps even more so?:
See about 1 minute 15 seconds into the video.
However, it's also possible that this particular 6x6 was underpowered, and/or could not generate enough torque to drive the second axle forwards?
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13. Speculation: How the Kamaz Typhoon Might Cross a Trench
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In the absence of concrete imagery, I would then speculate as follows. Although clearly a tandem-axles up front 6x6 is not going to be able to cross a trench or a ditch as smoothly as the 8x8 Tatra 815 shown above, it still seems possible that it would not be quite as likely to get “stuck”, as a 6x6 whose tandem-axles are located in the rear. Here is my reasoning.
Imagine a normal 6x6 trying to cross the first trench depicted above, as traversed by a Tatra 815 8x8. The minute the first axle of the normal 6x6 hits the trench, it will dive right in, and will get completely stuck. Sure, if the trench is shallow enough and the slopes soft enough, the 6x6 might be able to back up out of the trench, pulling that first axle up and back. But going forward would not be an option.
In the following diagram, the front axle of a standard 6x6 has dropped into the trench, and there is no escaping without recovery assistance:
The website advises: "Winch up the front end of the vehicle until the wheels clear the ditch. Then slowly reverse the vehicle back to solid ground. When safely away from the edge of the ditch, lower the wheels and unhitch your vehicle. If you have no winch, another vehicle may be used for power, though more rigging will be required." See http://www.landyonline.co.za/techtalk/vehicle_recovery.htm .
Note that even if this 6x6 had approached the ditch with considerable momentum and speed, the minute the front axle dropped into the ditch, the vehicle would have come to a shattering stop. All the momentum of the vehicle will have been transferred downwards, at an angle into the ditch.
Now imagine instead that a 6x6 with tandem-axles in front tries to cross the same trench. The first two axles are fine, and would merely duplicate the opening sequence we just saw above for the 8x8 Tatra 815, in post #1372. Once the third axle hits the trench, however, needless to say it drops right in.
However, if the trench is not too deep, then theoretically it seems at least possible that the 6x6 could still move forwards. The first two tandem axles would now be pulling the third axle up and out of the trench. And this might prove even more the case if one tries crossing the trench at considerable speed, with lots of forward momentum. Yes, when the third axle at the back of the vehicle hits the trench and drops down, the "bump" will be incredibly jarring. But with enough forward momentum, and with the rest of the vehicle's mass continuing to go forwards and now angled upwards, there might be enough force to pull the third axle out of the ditch or trench.
Put technically, the lines of force in a 6x6 with tandem axles forward seem to be theoretically more “favorable” to trench-crossing (within limits), than the lines of force in a conventional 6x6. The conventional 6x6 might be able to back up out of a bad “front axle stuck in a trench” situation, but it can't go forward. Whereas a 6x6 with tandem-axles up front wants to go forward, in order to get out of a bad situation in which its trailing single axle gets caught in a trench.
I am just wildly speculating here, so what I just wrote may be completely wrong-headed. If any of you guys have seen Tatra 813 6x6's with tandem-axles placed forward at truck trials, negotiating trenches, and would be willing to offer some practical insight, that would be most helpful indeed. This is a very specialized question, and it's really only those who have some experience either seeing 6x6's in action in truck trials, or better yet, driving such vehicles in truck trials, who would best be able to provide answers.....
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14. Turtling in a 6x6 that has Tandem-Axles up Front
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Just a brief aside: in the first video just posted, notice how the tandem-axles up front do not immunize this 6x6 from “turtling”. It is still just as vulnerable to getting stuck in this way; perhaps even more so?:
See about 1 minute 15 seconds into the video.
However, it's also possible that this particular 6x6 was underpowered, and/or could not generate enough torque to drive the second axle forwards?
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15. Some Truck Trials of Tatra 6x6's with Tandem-Axles up Front
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Here is a very large collection of videos that show the operational characteristics of various 6x6s with tandem-axles up front, negotiating very rough terrain during truck trials.
Just to anticipate: no, I do not think that the TerraLiner should be able to do the same. But I thought I would post these videos nonetheless, because they contain lots of information about the unique handling properties of this kind of axle-configuration. And to the experienced and educated eye (not my own!), they might suggest further reasons why Kamaz decided to place the tandem axles forward, in its Typhoon:
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15. Some Truck Trials of Tatra 6x6's with Tandem-Axles up Front
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Here is a very large collection of videos that show the operational characteristics of various 6x6s with tandem-axles up front, negotiating very rough terrain during truck trials.
Just to anticipate: no, I do not think that the TerraLiner should be able to do the same. But I thought I would post these videos nonetheless, because they contain lots of information about the unique handling properties of this kind of axle-configuration. And to the experienced and educated eye (not my own!), they might suggest further reasons why Kamaz decided to place the tandem axles forward, in its Typhoon:
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[video=youtube;EaHtccTJQCM]https://www.youtube.com/watch?v=EaHtccTJQCM [/video] [video=youtube;Gorq_IvaqqQ]https://www.youtube.com/watch?v=Gorq_IvaqqQ [/video] [video=youtube;a9pm9YpsNPI]https://www.youtube.com/watch?v=a9pm9YpsNPI [/video]
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[video=youtube;EaHtccTJQCM]https://www.youtube.com/watch?v=EaHtccTJQCM [/video] [video=youtube;Gorq_IvaqqQ]https://www.youtube.com/watch?v=Gorq_IvaqqQ [/video] [video=youtube;a9pm9YpsNPI]https://www.youtube.com/watch?v=a9pm9YpsNPI [/video]
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Again, what's really needed is a good, clear, simple video demonstration of a 6x6 with tandem-axles up front crossing various kinds of ditches and trenches. Or even the Kamaz Typhoon crossing a ditch or a trench!! I searched for at least 2 days trying to find such a video, and came up short. Instead, I found all of the videos above, of 6x6 truck trials.
They are interesting and fun to watch, but they still do not answer the question:
Is there is a distinct advantage to the Kamaz Typhoon's tandam-axles up front configuration, when it comes to crossing ditches and trenches?
If anyone reading this can provide a clear answer to this question, that would be terrific. Or, if anyone reading this finds a video that at least clarifies the question further, please post!
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Again, what's really needed is a good, clear, simple video demonstration of a 6x6 with tandem-axles up front crossing various kinds of ditches and trenches. Or even the Kamaz Typhoon crossing a ditch or a trench!! I searched for at least 2 days trying to find such a video, and came up short. Instead, I found all of the videos above, of 6x6 truck trials.
They are interesting and fun to watch, but they still do not answer the question:
Is there is a distinct advantage to the Kamaz Typhoon's tandam-axles up front configuration, when it comes to crossing ditches and trenches?
If anyone reading this can provide a clear answer to this question, that would be terrific. Or, if anyone reading this finds a video that at least clarifies the question further, please post!
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16. Some Photos of Tatra 6x6's with Tandem-Axles up Front, in Truck Trials
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In contrast to videos, it seems much harder to find still images of Tatra 813 6x6's doing wild and crazy in truck trials. Probably the best website I've yet come across is a thread packed with photos at http://bagry.cz/cze/forum/bagry_cz/tatra_813 , http://bagry.cz/cze/forum/bagry_cz/tatra_813/(offset)/40 , and http://bagry.cz/cze/forum/bagry_cz/tatra_813/(offset)/80 . I found other photos at http://honzaplzenak.euweb.cz/2010/02/Tatra-813-6x6-Jardy-Klinkacka-(to-je-predloha).html , http://heavycherry.com/machineinfo/tatra/-813_6x6-1980-truck_over_7_5t-breakdown_truck.html , and http://www.saxi.cz/index.php?page=exponat&idexp=23 .
As you look through these, recall the much more sedate photos of Tatra 813 6x6's in their original role, as Ballast Tow Trucks -- see posts #1360 to #1365, on pages 136 and 137, at http://www.expeditionportal.com/for...edition-RV-w-Rigid-Torsion-Free-Frame/page136 and http://www.expeditionportal.com/for...edition-RV-w-Rigid-Torsion-Free-Frame/page137 . It's really quite extraordinary to realize that a Ballast Tow Truck could be repurposed to become such an excellent machine for truck-trials -- see http://en.wikipedia.org/wiki/Tatra_813 :
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16. Some Photos of Tatra 6x6's with Tandem-Axles up Front, in Truck Trials
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In contrast to videos, it seems much harder to find still images of Tatra 813 6x6's doing wild and crazy in truck trials. Probably the best website I've yet come across is a thread packed with photos at http://bagry.cz/cze/forum/bagry_cz/tatra_813 , http://bagry.cz/cze/forum/bagry_cz/tatra_813/(offset)/40 , and http://bagry.cz/cze/forum/bagry_cz/tatra_813/(offset)/80 . I found other photos at http://honzaplzenak.euweb.cz/2010/02/Tatra-813-6x6-Jardy-Klinkacka-(to-je-predloha).html , http://heavycherry.com/machineinfo/tatra/-813_6x6-1980-truck_over_7_5t-breakdown_truck.html , and http://www.saxi.cz/index.php?page=exponat&idexp=23 .
As you look through these, recall the much more sedate photos of Tatra 813 6x6's in their original role, as Ballast Tow Trucks -- see posts #1360 to #1365, on pages 136 and 137, at http://www.expeditionportal.com/for...edition-RV-w-Rigid-Torsion-Free-Frame/page136 and http://www.expeditionportal.com/for...edition-RV-w-Rigid-Torsion-Free-Frame/page137 . It's really quite extraordinary to realize that a Ballast Tow Truck could be repurposed to become such an excellent machine for truck-trials -- see http://en.wikipedia.org/wiki/Tatra_813 :
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Whereas in this sequence, although the Tatra 813 6x6 comes close to flipping, it manages to right itself, and makes it down the hill:
Here are two good side-elevations of the Tatra 813 6x6:
At just 7.76 m long, the Tatra 813 "Ballast Tow Tractor" is certainly much shorter than the intended length of the TerraLiner, which will be roughly 10.5 m.
However, given that the Kamaz Typhoon is a very new machine -- designed in 2010, and having entered service only in 2014 -- there are not many pictures or videos on the web yet of the Typhoon "in action", coping with challenging situations and obstacles. See http://en.wikipedia.org/wiki/Kamaz_Typhoon , https://ru.wikipedia.org/wiki/КАМАЗ-63968_«Тайфун» , http://www.military-today.com/apc/kamaz_taifun.htm , http://www.army-technology.com/projects/kamaz-63969-typhoon-mrap-armoured-vehicle/ , http://www.armyrecognition.com/russ...ruck_technical_data_sheet_pictures_video.html , http://www.deagel.com/Tactical-Vehicles/Kamaz-63968_a002964002.aspx , http://www.army-guide.com/eng/product4748.html , http://huntsmanblog.ru/kamaz-63969-taifun/ , http://photo-find.ru/?p=3118 , and http://army-news.ru/2011/12/broneavtomobil-kamaz-tajfun/ .
So the Tatra 813 6x6 seemed very much worth writing and thinking about, too, and illustrating with lots of pictures and videos: because if the TerraLiner does opt for a Tandem-axles-foward configuration, this Tatra is the closest analog for which abundant information is available.
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Whereas in this sequence, although the Tatra 813 6x6 comes close to flipping, it manages to right itself, and makes it down the hill:
Here are two good side-elevations of the Tatra 813 6x6:
At just 7.76 m long, the Tatra 813 "Ballast Tow Tractor" is certainly much shorter than the intended length of the TerraLiner, which will be roughly 10.5 m.
However, given that the Kamaz Typhoon is a very new machine -- designed in 2010, and having entered service only in 2014 -- there are not many pictures or videos on the web yet of the Typhoon "in action", coping with challenging situations and obstacles. See http://en.wikipedia.org/wiki/Kamaz_Typhoon , https://ru.wikipedia.org/wiki/КАМАЗ-63968_«Тайфун» , http://www.military-today.com/apc/kamaz_taifun.htm , http://www.army-technology.com/projects/kamaz-63969-typhoon-mrap-armoured-vehicle/ , http://www.armyrecognition.com/russ...ruck_technical_data_sheet_pictures_video.html , http://www.deagel.com/Tactical-Vehicles/Kamaz-63968_a002964002.aspx , http://www.army-guide.com/eng/product4748.html , http://huntsmanblog.ru/kamaz-63969-taifun/ , http://photo-find.ru/?p=3118 , and http://army-news.ru/2011/12/broneavtomobil-kamaz-tajfun/ .
So the Tatra 813 6x6 seemed very much worth writing and thinking about, too, and illustrating with lots of pictures and videos: because if the TerraLiner does opt for a Tandem-axles-foward configuration, this Tatra is the closest analog for which abundant information is available.
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