Fat Tire Mini bike

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    13-Jul-2015

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  • Fat-tire scooter for sportsmen

    FOR TRANSPORTATION across the wilds, youcan't beat this iron packhorse. Its power-mowerengine sends it over rough terrain at speeds upto 10 m.p.h.gets you to remote hunting andfishing sites ahead of your footsore companions.

    An extendable rear rack takes your equipmentload off your back, and carts clumsy-to-carrygame back to the campsite. When this pack rackisn't needed, you just slip out the extensionpipes, or just leave them in place, capping theframe-pipe ends with crutch tips to keep theextensions from working out.

    Though it's possible to up the speed byswitching the transmission sprockets (puttingthe large sprocket on the top shaft and the smallone on the bottom), the scooter's not intendedfor public roads. You store it at your huntingcabin. Or truck it to road's end in your stationwagon or the trunk of a large car. The wholefront fork of the scooter detaches for easierloading.

    Since the overall weight is around 150 lbs.,you won't want to back-pack it very farshouldyou run into a stretch of country that forces youto dismount. For portage, in such cases, youjust remove the fork, strap it on top of the seat,disengage the drive belt, lift the scooter by thefront stirrups and "wheelbarrow" it.

    The frame design is simple but logical. Those

    Its low speed and rugged constructionare ideal for wilderness travel

    and those fat tires assure a smooth ridewith sure-footed traction

    even on rough, trackless terrain

  • The brake lever is pivoted on top of the rear wheel'shub plate, with a bearing plate between for clearance.The band passes around a drum bolted to the wheelrim. The ends are looped over a pin protruding fromthe lever's rear face

    The brake rod passes forward from the lever to thebrake pedal at the right stirrup. Note how the pedalangles inward for maximum foot roomand to avoidsnagging on underbrush. The fork permits rod adjust-ment

    The seat attaches to the frame with adjustable brack-ets, shifts back and forth for most comfortable posi-tion. Cord coiled around the cross bar is the condenserwire, extended so it can be attached to a hand-heldemergency switch that kills the motor

    stirrups protect your feet from jutting rocks. Theside braces spread low underbrush to let thescooter pass.

    You needn't follow the dimensions exactly asgiven in the plans. The model shown is a basicmachine, intended to demonstrate how simply arugged scooter can be made. While the frameshown is welded up from 1-in. furniture tubing

  • (for light weight) there's no reason why youcouldn't use common 3/4-in. pipe or rigid conduit.Also, to avoid the bending, you could joinstraight lengths with angle iron. Such jointsshould, however, be reinforced with gussets,since the frame must stand up to severe stressesfrom jolting over rough ground. You'll also needformed channel for the frame base and transmis-sion rack and steel plate for the engine deck. It'sbest if axles aren't threaded at the ends, since

    6" SPROCKET J

    Vt" V-BELT

  • there's too much chance of their being "peened"by scraping past stones. Rather, they should beretained with cotter pins and washers. Specialpivoting retainers can be made by welding anL-shape of 1/4-in. rod to one face of a washerlarge enough to slip onto the axle you've chosen.The tail of the L enters a hole in the plate, hold-ing the axle in place in the notch. (The hub nutshown on the front axle is an alternate treat-ment. )

    But the main feature is that rear wheel. The12-by-16 aircraft-type Terra-Tire has no tubeand is kept at only 12 lbs. pressure. It simplycups itself around small boulders and logs in itspath, smoothing your ride. (An 8-in. groundclearance keeps the frame from hanging up onthese small obstructions.) It's virtually impos-sible to spin such a tire in loose soil or mud, oron ice. It floats along on top of sand, making thistrail-blazer a practical beach buggy, as well.

    The front tire's a 6-by-6 snow-and-mud tread;you keep its tube at 15-20 lbs. pressure. Boththese tires can be obtained from an industrialtire dealer or (if you're lucky) at a war surplusstore, where you might also find the variouspulleys and sprockets. Wide-base rims are avail-able in both pressed steel and aluminum.

    uprights are tubingThe uprights of the front fork section are

    also 1-in. furniture tubing or 3/4-in. pipe. Thecross members, including the two pivot brackets,are angle iron (or bed rails). These are spacedso that the frame's steering column will seatsnugly between them. The lock pin is thendropped through. This pin is 5/8-in.-dia. rod, withan L of 1/4-in. rod welded at the top. This hooksover the upper pivot bracket to keep the pinfrom dropping through to the ground. It alsoprovides a handle to facilitate withdrawal, oncethe cotter pin at the opposite end has been re-moved.

    Unless you can lap this pin into the framecolumn for a snug fit, it should ride within bush-ings pressed into both ends of the column pipe.In the model shown, 5/8-in. I.D. Oilite bushingswere used.

    The transmission rack consists of two channeluprights with bearing housings welded at bothends. These housings are merely short lengths ofpipe with an inside diameter that will provide asnug fit for the bearings you use. The two up-rights are welded to opposite ends of a pipebrace; the jack shafts are slipped through thebearings and held fast with retaining collars. This

    entire assembly is mounted in the frame bymeans of simple mechanical pivots. The lowerbearing housings protrude into holes in the sup-port plates at each side. The pivoting featurepermits adjustment to keep the drive belt taut.

    The rack is tensioned against the belt bymeans of a spring hooked between two flat-ironbrackets. The front bracket is drilled to slipover a pin projecting from the top of the rack.The rear bracket is bolted to the frame. Whetheryou add a screen (or shroud) around the trans-mission depends on the use (or abuse) you'llgive the scooter.

    If you're using a power-mower engine, it mayalready be equipped with a centrifugal or auto-matic clutch. If not, you can order one from theV-Plex Clutch Co. of Hagerstown, Ind. Thescooter shown uses a four-cycle engine with aself-adjusting V-Plex, and the engine-to-wheelratio is 25-30 to 1 (depending on the clutchdiameterwhich in turn depends on the load ata given moment). A slightly higher ratio (around35 to 1) is recommended for a two-cycle engine.

    dead man's controlKeep in mind that this rig is really a two-wheel

    tractor. If you start it up with the throttle ad-vanced, it'll take off instantlywith grim de-termination, and a mind of its own. So it's a goodidea to have an emergency switch within easyreachperhaps a hand-held, spring-loadeddead man control which will douse the enginethe moment you release your grip. You couldpart the condenser wire and insert a pushbuttonswitch, mounting it on the handlebar so you cankeep your finger on the button while you steer.If the button is released, it breaks the ignitioncircuit. Or, you might use a hand-throttle with asufficiently powerful return spring to starve thecarburetor when released.

    Engine compression supplies adequate brak-ing, but it's a good idea to equip the rear wheelwith a brake drum so you can install the pedalbrake shown.

    Remember also that it's no trick to make theshafts on the idler pulleys long enough to usethem as power take-offs for a water pump orgenerator. So if anybody shouts "Get a horse!"at you when you chug past them on the trail,you can grin smugly. What pack animal candouble as a pumping station or camp-site powerhouse? And this mount is cheap to feed. Withthe 2-1/2-hp engine shown, a gallon of gas shouldscoot you through the wilds for nearly six hours.