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R/C Steam
Tractor Tank
Contents of this website are freeware and/or copyrighted material, and may not be sold
under any circumstances.
Email: dogsbody@steamhobby.com
Home:
https://steamhobby.com
1. Credits & Specs
Much kudos to Crabfu for
his Steam
Lobster tank. All R/C steam & fire
goodness. I took one look & decided I must have one.
You can't buy these things off the shelf, so that meant building
it!
Chassis: Tamiya
1/16 King Tiger (clutch drive)
Power: Regner MIDI
Marine Plant, plus PM Research steam whistle
Fuel: Propane/Butane
mix (camping fuel)
Boiler
Pressure:
30+ PSI
Body: Aluminum
Sheet Metal & Brass Fittings
R/C: Spektrum
DX6, two Futaba S3010 servos, one Spektrum S75 miniservo
Runtime: 15-20 minutes
Weight: 13 lbs
(empty)
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r/c steam engine
powered tractor tank
2. Mechanics
Like Crabfu's lobster, my R/C steam tank uses 100% steam power for
propulsion. All
told it took about 3 months to assemble, although a good portion of
that was searching out then waiting for parts & various tools to
arrive. Much less than a month of actual fabrication,
spending a couple hours per night cutting
metal, drilling holes, etc...
Tamiya 1/16 King
Tiger Tank
The rc steam tractor is
based on
an
old Tamiya
1/16 scale King Tiger (KT)
tank from
eBay, so there are numerous mechanical differences from Crabfu's
1/16 Leopard tank based design.
The gearbox layout is
dissimilar and located at the front of the tank, the torsion bar
suspension complicates mounting brackets, and the chassis rear is open
after the plastic body-work is removed. For my tractor, I
reversed things placing the gearbox at the back.
As did Crabfu, I used a Regner MIDI
Marine plant for boiler & steam engine to replace the KT's original
electric
motor. Not cheap -- nothing about live-steam is cheap --
but
is compact & gives plenty of power. |
Regner MIDI |
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R/C Steam Engine Mount
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The boiler & fuel
tank
base-plate was replaced with one fabricated
to fit around the KT's torsion spring suspension. The motor
was
fitted to a bracket sitting on top the KT's
gearbox. Meccano
sprocket gears & chain drop to a 4mm axle, one end filed to match
the original pinion gear. The pinion gear subsequently powers the
unmodified skid steering clutch & gearbox.
I ground the axle by first
sliding on two oiled flanged bushings, which
were then held in my vise. Attach a drill & you've a
crude lathe. Once running I carefully filed the 4mm axle
down to
0.125" matching the pinion, occasionally adding more oil to the
flanges.
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Mounting Brackets
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Wood heat shields made
from oak protect the plastic Tamiya skid clutch
(behind
the boiler) and the servos (in front). The rear heat shield
is wrapped with aluminum on the clutch side, to avoid engine oil
spatter
soaking into the wood.
A PM Research whistle was added to the boiler. Minor
challenge there, since the whistle takes a 1/4" 40TPI threaded pipe,
and the boiler a 6mm 0.75 pitch metric (M6x0.75) threaded pipe.
Fortunately the boiler threads are close to 1/4" 32TPI, so I took a
1/4-40 to 1/4-32 adapter & rethreaded
the latter section. |
Whistle
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A bracket was fabricated
to hold the servos &
front heat shield in place. Another bracket holds the R/C
receiver, headlight adapter &
battery. The headlight adapter is basically a light
switch controlled directly by the Spektrum receiver.
Servos control the skid steering clutch, engine reverse/throttle valve,
and rc steam whistle. All servos are tucked into the front
of
the tank, hidden behind the front heat shield. For the most
part, only control rods are visible when looking down into the boiler
section. A triangular
shaped bracket redirects
the horizontal whistle servo motion into a vertical tug on the whistle
chain. |
Headlight Adapter
Schematic
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Internal Pictures
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3. Body
Obviously, I based the tractor-tank's body on Crabfu's
lobster. I used ideas from both
his concept drawings & metal work. I also added various
wood
trim & brass fittings, in keeping with the organic Victorian
Steampunk theme.
The body is mostly composed of 0.032" K&S Aluminum sheets,
which are easy to cut & bend. The design used up quite
a few of them. Hand tools, drill & a vise were all that
it
took. Fasteners on the finished tank are brass hex screws,
for a classic
bolted-together look. None of the fasteners are decorative
-- they're all holding something together.
Other than a couple rough drawings, I
mostly fabricated on the fly, starting with the lobster
tail. I penciled patterns onto the aluminum, checked
symmetry with a ruler, started cutting, then filed away any rough
edges. After making
one tail segment, it became the template for
the others.
Next I made the track fenders (from a larger sheet bought at Home
Depot), side boiler
panels, then
finally the various front end elements. Some brass u-shape
channel trim covers the raw aluminum edges around the boiler and front
deck plate.
The open section in the center makes it easy to see the steam motor
& boiler. The lobster tail does a good job hiding the
King Tiger gearbox. The front aluminum top
plate was J-B Welded (high temp epoxy) to brackets hidden inside, then
trimmed out with
Mahogany decking strips. The strips were first attached to
a dark
paper
backing, then to the deck plate as an assembly.
Thermal paint, soldered brass railings, search
headlamps (functional!), and Union Jack attached to the KT's old
antenna add some finishing touches. Still left to do
is blackening of the metal tracks & perhaps adding some brass
portholes along the side.
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4. Materials List
& Vendors
- Tamiya 1/16 King Tiger 56004 (from eBay)
- Spektrum DX6 Radio
& AR6000 Receiver
- Two Futaba S3010 servo's & one Spektrum S75 miniservo
- Meccano Sprockets 3/4" diameter, 1" diameter, plus chain
(from eBay)
- Other Supplies (Home Depot, Kragen, etc...)
- Mahogany
Strips (1/8" x 1/4" x 24") - Body trim
- High Temperature Engine Enamel Paint
- Oak Trim Panel (3.5" x 24" x 1/4") - Boiler heat
shields
- Aluminum Sheets (6" x 18" x 1/32") - Track fenders
- 4-32 screws/washers/nuts
- Loctite Thread Locker
- J-B Weld
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