N Scale 40'+ Containers Missing Chassis Tunnels?

tehachapifan Jun 12, 2021

  1. tehachapifan

    tehachapifan TrainBoard Member

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    Been eyeing some great looking (1:160) container offerings from various manufacturers and am trying to decide which ones to settle on. One feature that I've seen omitted in the past with at least one 40'+ container offering was with what I believe is called the chassis "tunnel". This is a depressed rectangular area on the underside towards the front that the raised, forward area of a container chassis seats into. I believe this tunnel exists on all 40' containers and up (20 footers may not have these tunnels). Anyone run across any more recent offerings that don't include this detail? How about the Athearn and Atlas 40' containers? Minor detail that nobody will ever notice? Perhaps. But, if I'm trying to decide between 2 offerings that are otherwise pretty identical including price, this may be the tiebreaker. Plus, I may want to stage on or two on a chassis (well, assuming the dimensions match....don't get me started on that!).
     
  2. BigJake

    BigJake TrainBoard Member

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    Can you provide a photo of a chassis with this raised area that sticks up under the container?

    All the highway chassis I have seen are flat between the pins that engage the container's connectors on the edges/corners. I have seen low profile gooseneck chassis, with a raised area in front of where the container sits.

    Or are you talking about open-top dumpsters and their corresponding chassis? Those have a tunnel, and corresponding raised rib structure on the chassis. But I'm not sure I've seen trailer chassis for those; all I recall seeing were truck chassis.
     
  3. tehachapifan

    tehachapifan TrainBoard Member

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    Not talking about open-top dumpsters. This tunnel exists on all 40'+ shipping containers (at least the overseas kind but pretty sure domestic ones have it too). Maybe I'll try to snap a photo of an N scale container with the tunnel (might not be the correct term) and/or an N scale chassis with the raised area, but I don't have easy access to a real container or chassis.
     
  4. pmpexpress

    pmpexpress TrainBoard Member

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    tehachapifan is referring to a gooseneck tunnel.

    Located in between a number of the sub-floor cross-braces, the rectangular depression is in the forward portion of a container.

    Clearly visible on the underside and interior (i.e., where its metal top replaces some of the wood flooring) of a container, the tunnel serves to center the container on dedicated gooseneck intermodal trailers.

    The recesses also allow containers to be a bit taller, because they sit lower on gooseneck trailers.

    Athearn, Atlas, Deluxe Innovations (which are now manufactured by Fox Valley), Jacksonville Terminal Company (i.e., with an raised "T" molded in and an engraved "J " and "C" and "Made In China" text), and Walthers containers have this feature molded into their bottoms.

    Twenty-foot long containers do not have gooseneck tunnels.

    The topic of gooseneck intermodal trailers came up on page two of the kingj63's "3D printed 20' container chassis and more" TrainBoard thread.

    [​IMG]

    Picture by Tom Stefanac - Vaughan Weather - www.vaughanweather.com - Wikimedia Commons

    [​IMG]

    Picture by Danny Cornelissen - http://www.portpictures.nl - Wikimedia Commons
     
    Last edited: Jun 15, 2021
    digimar52 and tehachapifan like this.
  5. tehachapifan

    tehachapifan TrainBoard Member

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    Bingo!

    Thanks, pmpexpress, for the proto-photo and for the info on which N scale containers include this feature.
     
  6. BigJake

    BigJake TrainBoard Member

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    Thanks for the info, but I'm a little confused. I see the tunnel on the container, but the Wikipedia source for those images shows a corresponding gooseneck chassis that clearly does not need the tunnel. Look closely:
    [​IMG]
    The forward connectors are in the same plane as the top of the gooseneck section, so a recess is not even needed. The trailer may be configurable for tunneled containers (the support blocks in the middle and connectors on the tail end appear to be removable or adjustable), but one would have to ask "Why?"

    The recess appears only ~6" or less deep, while standard containers only come in 8.5' or 9.5' heights, a difference of 1'. So it's not like the lower position on a gooseneck chassis is enough to compensate for the high-cube containers.

    -- Confused - Arlington TX
     
  7. tehachapifan

    tehachapifan TrainBoard Member

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    It looks to me like the gooseneck is indeed a little higher than the forward pins. Regarding the purpose of the recess, I don't think it's intended to reduce the overall height of the container, but rather as an alignment aid when loading equipment is placing the container on the chassis. I believe there is another common chassis design, different than what is pictured, where the front pins are pointing horizontally vs. vertically and the container is first slid horizontally into them and then the rear is lowered. I believe this forward slide is where the tunnel comes in handy. But, I don't work with these things, so I may be wrong.

    ....looking at that pic some more, it's hard to say for sure now if the pins are on the same plane or not on that particular chassis. Since it uses only vertical pins, I suppose the tunnel isn't need for the forward slide alignment I mentioned. I guess it boils down to what the grey spacer looking things on the top of that chassis are, If those fit in between stiffening ribs on the bottom of the container, the goose neck would still go into the tunnel recess. If the ribs sit atop those spacers, then I guess it doesn't.
     
    Last edited: Jun 15, 2021
  8. BigJake

    BigJake TrainBoard Member

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    I zoomed in pretty tight on the forward end, and it appears to me that the bases of the pins are at the same height as the top of the gooseneck, if not slightly higher (best visible on the far side forward pin). It would make no sense for the trailer, in this configuration, with mid-length support blocks in raised positions, to have the gooseneck deck higher than the pin bases, since that would allow the front of a non-tunneled container to rock sideways across the gooseneck section.

    It is hard to tell, but the forward connector pins appear able to be pivoted, and maybe reversed, to face rearward for the slide-on (or drive under) use you mentioned.

    Again, I can see the purpose of the tunnel, and even the configurability of the trailer to make use of it. I just don't see a commensurate benefit of lowering the container by ~6". Does that much change in height significantly affect wind resistance or handling (CG) on the road? Perhaps, but it would be less than the difference between standard and high-cube containers.
     
  9. tehachapifan

    tehachapifan TrainBoard Member

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    OK, I think I have the chassis in the pic figured out....maybe. There appears to be 2 sets of additional mounting pins at about the midway point that can be rotated up for up to 2 20' containers and down for a longer container. The rear extends for varying container lengths/configurations. I think the grey spacers can raise and lower depending on the container arrangement (up for 20 footers that don't have tunnels and down for longer containers that do have tunnels. The rearmost pins appear that they can can be raised or lowered as needed as well.
     
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  10. BigJake

    BigJake TrainBoard Member

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    Yeah, it is a really versatile container trailer!
     
  11. BigJake

    BigJake TrainBoard Member

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    It looked to me like the gray spacers shown in the middle:
    1. are raiseable and lowerable, to allow a tunnel-equipped container to sit lower on the trailer, or to support a non-tunneled container (or two 20 footers like you mentioned)
    2. are longer than the spans between lateral beams on the underside of a container, so if raised they would support the container via those beams
    3. might interfere with trying to slide a container onto the trailer lengthwise, if they are raised
     
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  12. tehachapifan

    tehachapifan TrainBoard Member

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    Yep, I think that's it.

    Nice chassis indeed, though it has a look like it's not a US prototype.
     
  13. pmpexpress

    pmpexpress TrainBoard Member

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    Manufactured by the Werlte, Germany based Krone, the tri-axle gooseneck intermodal trailer seen in the Wikipedia photo is unique, in that it is a fully adjustable chassis that can accommodate twenty to forty-five foot long containers.

    https://www.krone-trailer.com/engli...lties/fully-flexible-for-all-container-sizes/

    https://www.krone-trailer.com/english/products/container-chassis/

    In foreign countries, tri-axle ISO container chassis are quite common.

    Although the majority of ISO container trailers that are used in the United States are two axle, a tri-axle chassis is needed to carry twenty-foot long containers weighing more than 36,000 pounds, or forty-foot containers weighing more than 44,000 lbs.

    One should not inadvertently misidentify a gooseneck intermodal chassis design.

    While gooseneck container chassis and specialized tank container chassis are somewhat similar in appearance, because liquid loads are much heavier than dry goods are, and liquids shift while they are in transit, a tank container chassis, has a lower center of gravity, a larger gooseneck, and may have a spread-axle, rather than a tri-axle design that accommodates heavier loads, while lowering a trailer's tare weight.

    In North America, tank container chassis can be ordered in bi-axle, tri-axle, and spread-axle configurations.
     
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  14. pmpexpress

    pmpexpress TrainBoard Member

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    You're welcome.

    Quite happy to assist.
     

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