With a gasoline rig the expenses will be approximately as follows:
| Engineer, wages and expenses | $ 5.00 |
| Two pitchers, at $3.00 | 6.00 |
| Four men and teams | 20.00 |
| 60 gallons of gasoline at 15c | 9.00 |
| Lubricating oil | 1.00 |
| Cost per day | $41.00 |
Taking 1,500 bushels (wheat) as a day’s work, the cost of threshing figures out at 2¾ cents per bushel.
According to data furnished by the M. Rumely Company, which is based on an actual test, the total cost of plowing, seeding, cutting and threshing, including ground rental and depreciation, amounted to $8.65 with horses and $6.55 with their oil tractor. These figures will of course vary in individual cases, but are principally of interest in showing the comparative cost of horse and tractor operation.
With a gasoline or oil tractor equipped with engine plows one man can tend to both the plows and the engine, although some operators prefer to have two men, one relieving the other consequently plowing more acres per day and reducing the cost per acre. In some cases one man is placed on the plows and the other on the engine. By running the tractor twenty-four hours per day, with two shifts of men, a much better showing is made by the tractor when compared with horse plowing, for with the latter method it would be necessary to supply twice the number of horses.
To show the relative merits of various grades of fuel we will print the data kindly furnished by Fairbanks Morse for a ten hour day.
| ITEM | Fuel Oil 3c | Kerosene 6½c | Gasoline 15c |
|---|---|---|---|
| 60 Gallons Fuel | $1.80 | $3.90 | $ 9.00 |
| Lubricants | .40 | .40 | .40 |
| Engineer | 3.50 | 3.50 | 3.50 |
| Plowman | 2.00 | 2.00 | 2.00 |
| Repairs | .12 | .12 | .12 |
| Cost to Plow 24 Acres | 7.82 | 9.92 | 15.02 |
| Cost per Acre | .32 | .41 | .63 |
Plowing at the rate of 20 acres per day, and kerosene at 6⅔ cents per gallon, the Rumely Company obtain the cost of plowing one acre as $0.66. In the latter figure the interest and depreciation are included which will increase the figures over those given by Fairbanks Morse. It should be understood that these costs are approximate and will vary considerably in different localities and under various conditions.
Oil Injection Engines.
Engines using low grade fuels such as kerosene, usually experience much trouble in obtaining a proper mixture when the fuel is vaporized in an external carbureter even when the carbureter is specially designed for the heavy oil. This leads to fuel waste, starting troubles and cylinder carbonization, to say nothing of the objections of an odorous, dirty exhaust. To overcome the objections of carbureting the heavy oils it has been common practice to inject or aspirate a small amount of water, the water vapor tending to prevent the fuel from cracking and to distribute the temperature more uniformly through the stroke. The injection of water is not a particularly desirable feature, since its use involves one more adjustment and possible source of trouble when running on variable loads.