Almost finished, the OilPull gets a test fire before final painting and detailing.
Do you have an engine that is heavy and awkward to move around? A 3 HP Model M International gas engine isn't the heaviest engine around, but it takes good young muscle to move it. This engine is ideal to use for power on a model OilPull, however. It starts and runs well, and the sound of it running when the project is finished is worth every bit of the time and energy it takes to build.
I had never built wheels the size needed for the rear on this project, but I have made wheels for carts for gas engines many times, so I was sure I could do it. The 1/4-inch x 12-inch steel for the rear wheels was too heavy for a small roller, so it was rolled at a metal shop on a large roller, as were the 1/4-inch x six-inch front rims. The centers were flame-cut from 1/4-inch HR plate steel. Center holes were machined to fit the heavy wall tubing to accommodate the rear axle. The spokes on the rear wheels are made from 1/4-inch x 1-1/4-inch HR steel. Front wheels have a smaller flame-cut center and 1/4-inch x one-inch HR steel is used for the spokes.
The frame is all made from four-inch channel iron, and 1/4-inch HR plate (flame-cut to size) is used for most other parts. The floor panel is 1/8-inch HR material, and all the tinwork is made from 16-gauge HR.
The power train is two V-belts running from the engine to the shaft of a right angle gear box running a 1:1 ratio. This is also used as the clutch via a tensioner that acts on the belts from above. The output shaft from the gearbox is about six inches below the input shaft from the five-speed truck transmission, so two sprockets and a chain bring the power up to the input shaft on the transmission. There is a universal joint slip assembly that takes power to the differential from the transmission. The jack shafts come out of the differential to the outside of the main frame, on which the brake drums are mounted as are the sprockets that take power to the large sprockets on the main drive for the rear wheels.
The steering gear box is mounted on the main frame and is operated through three universal joints to give a smooth steering unit. The gearbox has a 10:1 ratio. The engine is mounted on a flat section that is slotted so it can be moved from front to back for any adjustments that may become necessary.
The radius rods are mounted to the front axle and to a cross member behind the steering gearbox. This gives the front end a solid and stable mounting. The seat is mounted on a flange bolted to the floor, and it swivels a full 360 degrees to make getting in and out of the seat easy.
The exhaust is piped into the 'smoke box' on the front of the tractor. This box is made in two sections; bottom section is 14-1/2-inch square x 21-inch high. For the sake of simplicity the top section is made separate, while the top and bottom sections are bolted together. The top section is fabricated from many pieces that were cut and welded to form the correct pattern.
The fenders are made from 16-gauge HR material and reinforced with 1/4-inch x one-inch plug, welded on edges for strength and stability. The canopy top is the only part that has any wood. A two-inch x six-inch piece was cut on a band saw to form the curve for the roof. The top is mounted on four pieces of one-inch x 1/8-inch angle iron. The whole project was put together, then disassembled and painted, and then reassembled. Trim and decals can be added as desired, and rubber can be put over the steel on the wheels for safety and stability.
Contact engine enthusiast Art Harnish at: 3593 18th St., Wayland, Ml 49348, (616) 793-3012.