EFFICIENCY OF GAS TRACTORS 



109 



greater horsepower in the maximum test. Even with a slight 

 increase in load, the majority of tractors consumed from 13 

 to 35 per cent, more fuel per unit of work. The present types 

 of tractor are considerably less flexible than the steam engine, 

 and infinitely less so than the horse. 



From the various motor contests, we obtain the following 

 table, which shows the amount of fuel consumed by gasoline 

 engines in various classes of work. The fuel consumption in 

 the brake tests increases with the number of cylinders, as is 

 to be expected. 



GASOLINE CONSUMED PER DELIVERED HORSEPOWER PER HOUR 



The gasoline used was of 70 specific, 64 Baume gravity. 

 The average consumption for 27 brake tests was 0.747 pounds, 

 or a trifle over a pint per horsepower hour. Nineteen brake 

 tests averaged 1.67 Ibs. and 12 hauling tests 1.91 Ibs. per 

 drawbar-horsepower hour. These averages are not strictly 

 comparable with each other, owing to the fact that some 

 tractors did not complete all of the tests and the data represent 

 results in two succeeding years. No kerosene tractor has as 

 yet achieved the thermal efficiency of the best gasoline tractors, 

 but in all but the most remote districts the wide and growing 

 disparity in fuel costs gives the former a marked commerical 

 advantage. 



Gas tractors have a wide range in speed, but for plowing 

 few travel over 1.75 to 2.25 miles per hour, and the majority 



