On Wed, 9 Sep 1998, Bill Richman wrote:
I believe you're talking about the Mattel
"Big Trak"? My nephews had one of
those many years ago.
Mine is labeled Milton Bradley. I still have my Big Trak, its box, and
its manual, and although some of the axils are busted, it still works!
I believe it used tank-type steering; six wheels, and
it could either lock
one set and pivot using the others, or reverse one side.
It has six wheels; three on each side.
The middle wheel on each side is a drive wheel. To turn, it turns one of
these wheels forward and the other backward. So it does a nice pivot.
I've got some surplus gearboxes and motors from
the Big Trak that I
purchased several years ago. They're kind of neat; they have two motors and
gear trains, linked together with a couple of big magnets. If you run both
in the same direction, the magnets are strong enough to force both motors to
turn at the same speed. If you reverse one of the motors, the magnets
alternately repel and attract. This either forces the machine to drive in a
straight line, or to pivot about its center, respectively. They also have
an optical interrupter on one gear so the CPU can tell how far the motors
have turned.
Cool! The turning never worked that well for me, but I think it had more
to do with uneven floors than with the Big Trak. A value of 15 was
supposed to do a 90 degree turn, but sometimes it took 14 or 16 and it
made programming difficult. I had to keep re-entering the programs for a
particular patch of floor, and the effect of just having it follow me into
a room and shoot someone of my choosing was lost. :)
My Big Trak's biggest problem was (and is) breaking plastic. First it was
the tabs that held the D cells in place, then it was the front axil, then
one of the back axils.
When I play with it now, I hold the batteries in place by forcing a
broken popsicle stick into the hole in the cover, which acts to keep the
plastic tab in place. Eventually this might stress the plastic and cause
more breakage. :/
The front axil is held together with electrical tape.
The back axil has been drilled through and bolted into place. It was a
repair my father made when I was a kid. It's not quite straight, though,
so the wheel doesn't turn freely.
But it's still a cool toy. I drag it out about once every two years and
have it drive around the house.
When I was a kid I had some sheets of paper that I had written programs
on, but those must have been tossed out or recycled years ago.
It had a hookup to dump the trailer, and I think some
other
options that never were released. It was a pretty cool toy.
The trailer was the Big Trak Transport. It looks highly breakable. :)
I'll have to check these out. :)
Bill Richman
incolor.inetnebr.com/bill_r
(Home of the COSMAC Elf
microcomputer simulator!)
Doug Spence
ds_spenc(a)alcor.concordia.ca
http://alcor.concordia.ca/~ds_spenc/