In Loving Memory of Simone Gauthier,
August 26th, 1915 - February 18th, 2008

Thursday, June 2, 2005

Radio Control Tractor Trailer, the concept

See the original post at DieCastoms Website

R / C . T r a c t o r . T r a i l e r ! !

..I am looking to custom build a large, radio control
Tractor Trailer. I think I will use a cab-over design to have the
most engine room, and hide the fact that it will have a weed whacker
engine in it, hopefully I can make a good looking static model out of
it as well. I"m thinking 1/10 or 1/6 scale, what do you think of

..I am having trouble finding people willing to help, even just advice
answers tips and things, all the websites I have found as-of-yet don't
make all that much sense or look like they were built by 12 year olds.
Most have little or no useful information to me.

..I am trying to figure out what to use for a rear differential. I'm
worried about using a straight axle. The short wheelbase, with most
weight being over the front end makes me think it may work fine, but
if I put enough weight on the trailer, it may not steer.

..I have drawn up plans (not to scale yet) to custom-build a diff with
my Dad (who is a blacksmith, and a welder-fabricator by trade) out of
six 90degree bevel gears (4 inside, one outside, one on driveshaft).
I tested my design with Lego's (Don't laugh) It worked. I don't see
why it will not work on a larger application. The draw back is that
it will be all open.

..My third idea rests with the differential out of something like a
Lark Motor Scooter.. The diff is enclosed, 4 inch Dia, 6 inch long
"tin can" shape. Considering such a wheel chair is designed to move a
person, plus the weight of their belongings, plus the weight of the
chair itself, I imagine it should be suitable for this. You?

..I had a battery toy truck when I was a kid that used a rocking
mechanism to try to keep all 4 rear tires grounded. I think I will try
the same with this, but I'll need universal joints. Weed whackers
tend to employ flexible drives housed inside the pipe-handle. Maybe I
can use that to my advantage?

..I also wonder if I might be able to find a variable, shiftable gearbox
(hopefully even radio operated?) or at least a forward-reverse. I
have no ideas on that as of yet. Do you?

..I need a radio.

..For the moment I will take a 2 channel but every time I type
anything about this truck I think of ways I could use more channels..

..I NEED throttle and steering obviously, and brakes if equipped can
be added to the throttle control easily enough I think.

..I would also like to add a kill switch since 99% of weed eaters have
them, and it would be nice to be able to immediately kill the engine if
something is wrong, and if the receiver has the right functions, kill
the engine when the signal is lost. I know there are model airplanes
that "level out make a 180" if the signal drops. If I can find one, I
want to use the Torro weed eater with the electric start option so the
truck will be really hands off operable. It would be nice at a fair
to sit back and see some kid gloat over the awesome giant model truck,
and start it from where ever I am sitting and drive it around a little
:) The start and kill functions could easily be controlled with the
same servo. Now we are up to 3 channel.

..If I find a suitable gearbox, that can be operated by servo, that
will be 4 channels.. What is your input on that?

..I'm hoping to keep the cost of this down as I haven't much money to
throw at it. Dad things he can find allot of what we might need for
the chassis in the scrap pile at work. The cab can be a simple
painted box for now, unless I find a suitable model truck to scavenge.

..I was thinking push mower wheels or old kid's wagon wheels until I
find something better. Maybe 2 or 3 side-by-side will make an
appropriate single wheel/tire. We have a mower here with a blown
engine.. Another option slightly more expensive would be pneumatic
tires from hand trucks, dollies (I just realized, a hand truck with
the bottom plate removed, a deck added, and a modified handle will
make the perfect trailer, about 5 feet long :-) )

..Any idea on adding "Diesel smoke" and making the engine sound a little
more real? It will have side-pipe of course.