A Pair of Model Oil Pulls

Double cylinder OilPull model

Figure 1 : For his double cylinder OilPull model, Jim Patton used lightweight aluminum pistons and fabricated entirely new connecting rods from steel tubing. This eliminated many of the problems in balancing the engine. The finished tractor shows very lit

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R.R. 1, Box 28-A Atkins, IA 52206

Nearly ten years ago, Jim Patton of Hiawatha, Iowa started collecting pieces to build a model of the Rumely OilPull tractor. The plan was to build a single cylinder tractor which strongly resembled the original OilPull design. However, in order to make the model suitable for parades and other events, rubber tires were used instead of steel wheels, and the drive train saw extensive modification from the original design. In other words, Jim was concocting a design that looked like yesterday's technology, but embodied a lot of modern engineering design as well.

The first of Jim's OilPull models went into actual construction during 1979, and was completed in 1980. Weighing about 800 pounds, it is small enough to fit into a pickup or onto a small trailer. This makes it an ideal model to take to a show or to a parade.

Shortly after completing the single cylinder OilPull, Jim began collecting pieces for a double cylinder model. This one required far more pieces, and far more work to complete, but construction began in 1984, with final completion in 1986. The two-cylinder model operates at 375 rpm, and has a top ground travel of 4? mph. It weighs about 1,200 pounds.

Both OilPull models use Fairbanks-Morse 3 hp 'ZC' engines. Only a single engine was required for the smaller model, with a pair of them being used in the latest design. The double cylinder model fires 360 degrees apart, just like the original OilPull. The cranks were cut to size and welded together using Eutectic 680 rod. This particular alloy is very expensive, but has the qualities needed for a weld that will be under high stress. The single cylinder model is water cooled, but the double uses an oil coolant, just like the original. Both models employ the Rumely cooling system of induced draft created by the engine exhaust. Rather than use the radiator sections of Rumely, the Patton models have a series of vertical flues within the cooling tank.

Clutches for both models were adapted from ordinary lineshaft clutch pulleys. Jim reworked these to include the drive shoes in a manner virtually identical to the Rumely design. The drive train for both models is built from the transaxles of Wheel Horse lawn tractors, although there were probably others which could be modified for this purpose. This eliminated the need for extensive external gearing, and permitted the use of the higher ground speeds required for parades. After consider able experimenting, a Schebler carburetor was finally used on the double cylinder model. Likewise, some experimenting was required to properly size the intake manifolds for smooth operation.

The engine in the double cylinder was, as previously noted, built from two Fairbanks-Morse 3 HP, 'ZC' engines. Setting both cranks together for 360 degree firing created balancing problems, so the first step was to minimize the problem by eliminating as much sliding and swinging weight as possible. This was achieved by the use of 35/8 inch aluminum pistons, plus the construction of lightweight tubular connecting rods. These are shown in Figure 1.

Figure 2 illustrates the completed single cylinder model on a parade run, and Figure 3 shows the progress in building the double cylinder engine. This photograph of February, 1985 indicates that the carburetor and ignition system are installed. Subsequently however, a Schebler carburetor was installed, and it pro vided better results.

Figure 4 shows the double cylinder engine after the crankshaft was installed. Even with the lightweight pistons and rods, obtaining a good running balance was achieved by adding suitable counterweights, and adjusting this weight through continued experiments. The finished engine displays no appreciable vibration at any speed from an idle up to its high idle of 375 rpm. Figure 5 illustrates the head end of the double cylinder engine after it was installed in the chassis.

Mr. Patton failed to keep close tab on the hours of work involved, but there is no doubt that the total figure would be astounding. We are sure that Jim has additional projects in mind, but our question in this regard only got a reply of 'No comment.'