102-20 Country Hill Drive Kitchener, Ontario, Canada N2E 1R7
In the spring of 1984 a lifelong ambition was realized when I finished the little John Deere AR pictured here.
A start in determining the scale of the model was made by the tires available, and the size of my lathe. 1:5 seemed the best, making the length 25', width 13', and height 11' to the radiator cap. This scale also allowed a 1' bore, for which commercial rings were available. The stroke is 1' valves, 3/8 diameter, and the plugs have x 32 thread.
All parts on this model are machined from the solid. No castings were made. The majority of structural parts are aluminum alloy, with cast iron pistons and wet sleeves. The valves are stainless steel. The aluminum rods have hardened wrist pins which work well, but the aluminum big end bearings running on the free machining steel crankshaft have to be watched carefully.
Progress is very slow in this type of job, but much time was saved by using gears from typewriters, etc. where possible. Some of those such as the steering gear and worm were purchased from Boston Gear.
An oil pump is incorporated giving force feed to the big end and main bearings. The thermo-siphon cooling system holds about 5 ounces, circulating through 54 1/8'' brass tubes in the radiator. The ignition is battery and coil, as it is impossible to scale down a magneto to this size.
The transmission has two speeds forward, with reverse, operated by the hand clutch with a 2 1/8''disk. Brakes are external contracting on the differential shaft.
Apart from much satisfaction listing to the little guy run, the experience I have gained gives me an appreciation of why John Deere eventually went to a double throat carburetor on their 2 cylinder engines. It seems that I will have to change the induction and carburetion also, if it is to work properly at idle.
Many thanks for helpful advice and encouragement go to friends, Mr. George Barrett and Mr. L.C. Mason, in particular. The latter's work may be known by modellers from his books and articles in Model Engineer.
I would be happy to hear from anyone wishing further information^