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Last week I posted about the completion of my first wire-following tractor trailer, which was a ten wheeler - a tractor-trailer, yes, but not a big rig in my mind.  Since childhood I have always considered that only tractor trailers with two axles on the trailer are truly "a big truck" - a big rig.  Thaty first tractor trailer with its one-axle trailer was a good and necessary exercise to build and study on my way to learning how built a true "big rig." 

That three-axle ten-wheeler ran surprisingly well even if it had a hard time on the narrow streets and tight corners of my layout's Main Street route.  I spent a lot of time using it this past week forexperiments in tractor-trailer-ology, looking into varying weight distribution, gearing, wheel size, component size and location, etc., as well as battery-pack shape and location other "trailer and tractor" issues - finding out what ideas work better or worse or not at all, what seems to be best. 

I then rebuilt the whole thing with few mods to the tractor a new tractor-trailer hitch design, an new type of battery pack, and most notably, a longer trailer with two axles.  This last change in a key to me:  I now have a "big rig"!!!!

This big rig is an superb runner, more tolerant than I ever thought a wire-following vehicle could possibly be of disturbances, bumps, jostles and abuse a road throws its way as if trying to trip it up.  This tractor is imperturbable, and seems to bull through tight turns and narrow streets, even if its gears grind a bit, regardless of the problems the trailer gives it to deal with.

This success is important to me not just because I have achieved an ability to understand how to build these things, but because having a complete big rig to test - to verify how sharply it can turn, change the incline of road it is running up or down, and how steeply it can climb, I can now set out to convert my country road - made for big-rigs, buses and higher-speed cars, so that I can runwire-following buses and big rigs.    That has been my goal all along . . .

Here is a link to the Youtube video of this truck running on my downtown loop.



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Last edited by Rich Melvin
Original Post
@GVDobler posted:

Very cool.

Is the motive power in the tractor rear wheels?

Yes, a tower motor (vertical shaft sticking up inside the front of the trailer) drives the rear axle.  The trailer slips over it and hitches to a post mounted on top of the motor housing. 


@Guitarmike posted:

. . . . I’d like to see you do that with a set of doubles. 😎

So would I.  Up soon . . . 

Last edited by Lee Willis

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