4 ms·

I read somewhere that these had a mechanism that made all of the wheels follow in roughly the same track, but I haven't been able to find an explanation of how

I read somewhere that these had a mechanism that made all of the wheels follow in roughly the same track, but I haven't been able to find an explanation of how they made that work. Anyone happen to have a link/explanation? Edit: Found this https://www.researchgate.net/figure/Steering-scheme-of-a-road-train-obtained-by-a-trailer-k-with-one-steerable-axle-attached_fig1_311309756 https://www.researchgate.net/figure/Steering-scheme-of-a-roa....

deleted 4y ago
[deleted]
ducttapecrown 4y ago
For those of us who don't understand engineering diagrams^1, could you write a summary of how it works? ^1: These are probably called schematics or something...
- healthysurf 4y ago
  My total guess not based on the drawings - the wheels of the cars move with a certain delay as a reaction to its tow bar getting turned. I would assume this delay can be configured on a per-car basis because the cars farther back may require more compensation than the ones in the front. Although I am calling it a delay, I assume the mechanism is mechanical and there is probably a better word to describe the action where the wheels do not turn at the same time or with the same severity as the tow bar.
  - a9h74j 4y ago
    Wheel-steering or axle-steering perhaps? Some actual locomotives have linkages to consistently steer individual axles to match the overal curvature of the track.
- robocat 4y ago
  I did a quick Google. Play with some keywords, especially searching for images: drawbar steering-angle turntable dolly Ackerman train The usual design is to use mechanical linkages to steer the wheels, with varying levels of complexity that have different compromises. A complicated double Ackermann example (scroll down for plan view): https://planindustrie.de/en/products/industrial-heavy-duty-drawbar-trailer/ackermann-steering/type-60/ https://planindustrie.de/en/products/industrial-heavy-duty-d... and look at other products of theirs from the menu for simpler linkage examples. Academic papers are about the design of linkages and turning paths, with consideration for tyre slippage, obstacle avoidance, following, etcetera. The more mathematical papers use an idealised world on a flat surface (ignoring: surface tilts; terrain elevation changes/steps; slippery or soft surfaces especially if variable). Some modern systems use computer controlled power and steering to wheels to help avoid the errors in reality of idealised systems. It is a huge industry, but we need a https://ciechanow.ski/ https://ciechanow.ski/ type person to give us a nice model to play with.
a9h74j 4y ago
My impression from the first picture in the article was that these might be so tightly coupled car-to-car, a single car tilting (L/R) into a hole might be impossible. More fancifully, imagine they were so tightly linked wrt front/back tilt, the land train could bridge gaps all by itself.

deleted 4y ago

[deleted]

ducttapecrown 4y ago

For those of us who don't understand engineering diagrams^1, could you write a summary of how it works? ^1: These are probably called schematics or something...

healthysurf 4y ago
My total guess not based on the drawings - the wheels of the cars move with a certain delay as a reaction to its tow bar getting turned. I would assume this delay can be configured on a per-car basis because the cars farther back may require more compensation than the ones in the front. Although I am calling it a delay, I assume the mechanism is mechanical and there is probably a better word to describe the action where the wheels do not turn at the same time or with the same severity as the tow bar.
- a9h74j 4y ago
  Wheel-steering or axle-steering perhaps? Some actual locomotives have linkages to consistently steer individual axles to match the overal curvature of the track.
robocat 4y ago
I did a quick Google. Play with some keywords, especially searching for images: drawbar steering-angle turntable dolly Ackerman train The usual design is to use mechanical linkages to steer the wheels, with varying levels of complexity that have different compromises. A complicated double Ackermann example (scroll down for plan view): https://planindustrie.de/en/products/industrial-heavy-duty-drawbar-trailer/ackermann-steering/type-60/ https://planindustrie.de/en/products/industrial-heavy-duty-d... and look at other products of theirs from the menu for simpler linkage examples. Academic papers are about the design of linkages and turning paths, with consideration for tyre slippage, obstacle avoidance, following, etcetera. The more mathematical papers use an idealised world on a flat surface (ignoring: surface tilts; terrain elevation changes/steps; slippery or soft surfaces especially if variable). Some modern systems use computer controlled power and steering to wheels to help avoid the errors in reality of idealised systems. It is a huge industry, but we need a https://ciechanow.ski/ https://ciechanow.ski/ type person to give us a nice model to play with.

a9h74j 4y ago

My impression from the first picture in the article was that these might be so tightly coupled car-to-car, a single car tilting (L/R) into a hole might be impossible. More fancifully, imagine they were so tightly linked wrt front/back tilt, the land train could bridge gaps all by itself.