314 



THE IRRIGATION AGE. 



FACTS AND FIGURES ON THE OIL 

 TRACTOR FOR THE FARM 



By A. G. Barnet 



The farmer contemplating buying a tractor 

 naturally thinks of what the machine will do for 

 him. How much it will save. He knows how 

 much time and labor it requires for the different 

 operations on the farm using horses, but the amount 

 the tractor will really do seems hard to estimate 



Fig. H E 1575. 15-25 H. P. Fairbanks-Morse Oil Tractor pulling six 14-inch plows 6 

 inches deep through sod on the farm of A. G. Russel north of Janesville, Wis. 



The manufacturers give the draw bar pull of 

 their engines. To figure the number of bottoms 

 which can be pulled, divide the draw bar pull by 

 the cross section of one plow, multiplied by the 

 draft per square inch of cross section of plow. 

 Thus, plow, 14 inch; depth, 6 inches; soil, clover. 



14x6x7 = 588 Ibs. draft 1 plow. 

 Let us say the draw bar pull is 4000 Ibs. and 

 the land is level and has good solid footing: 



4000 divided by 588 equals 6.8. 

 So we can safely estimate on at least six bottoms. 

 Each 1% of rise in grade rise of I ft. in 100 

 feet adds 1% of the weight of the i-actor and 

 plows to the draft. A 5 pluv gang 

 weighs about 3300 Ibs. and the best 

 field weight of a 15-25 horsepower tu. 

 tor is about 16,000 Ibs. 



Thus using the example shown 

 above of 5 14-inch plows plowing to 

 a depth of 6 inches, the drafts on a :.'/n 

 grade will be as follows : 



Sandy soil 1260 + 965 = 2225 

 Clay soil 3360 + 965=4325 

 Clover sod 2940 + 965 = 3865 

 Virgin sod 6300 + 695 = 7265 

 Gumbo 8400 + 965 = 9365 

 Mr. A. G. Russel of Janesville, Wis., 

 states : "In regard to my 15-25 oil 

 in view of the claims made by various manufac- tractor I would say I plowed 40 acres in 3 days and 

 turers. handled the plow and engine alone and pulled six 



Take the operation of plowing for instance. 14-inch plows 6 inches deep. The third day I 

 The farmer knows how much time and stock it j' plowed 14 acres in 9 hours on 25 gallons of kero- 

 requires to do the work. To estimate on the work sene, costing me 6J4 cents per gallon. At present 

 with a tractor one may use the following figures, I. am plowing sod, pulling the six 14-inch plows six 

 being certain always to note the exact nature of the inches deep and have plenty of power and get the 

 soil and the per cent of grade of the hills on the land, best of service." 



The most accurate tests on level 

 ground where the tractor gets a good 

 footing show the following draft per sq. 

 inch of cross section of plow. (Cross 

 section equals width of plow times depth 

 plowed.) 



In sandy soil draft is 3 Ibs. per sq. 

 inch of cross section of plow. 



In clay soil draft is 8 Ibs. per sq. inch 

 of cross section of plow. 



In clover sod draft is 7 Ibs. per sq. 

 inch of cross section of plow. 



In virgin sod draft is 15 Ibs. per sq. 

 inch of cross section of plow. 



In prairie sod draft is 15 Ibs. per sq. 

 inch of cross section of plow. 



In gumbo draft is 20 Ibs. per sq. inch 

 of cross section of plow. 



Taking for example a plow rig of 

 five 14-inch bottoms and wishing to plow 

 a depth of six inches figure the draft for the various 



Fig. H E 1695. 30-60 Fairbanks-Morse Oil Tractor pulling sixteen 14-inch plows at 

 depth of 5 to 6 inches. 



The draw bar pull of the machine Mr. Russel 



-oils as follows: (Cross section equals 5x14x6420 owns is 4000 pounds, so pulling the load he speaks 



sq. inch.) 



3x420=1260 Ibs. draft in sandy soil. 



8x420 = 3360 Ibs. draft in clay soil. 



7x420 = 2940 Ibs. draft in clover sod. 



15x420 = 6300 Ibs. draft in virgin sod. 



20x420 = 8400 Ibs. draft in gumbo. 



of is indeed a remarkable showing regardless of 

 how light the soil is. Using Mr. Russel's figures 

 shows a cost of 11 cents per acre for fuel. 



Another operation on which the farmer has 

 accurate figures is threshing. To begin with, with 

 a steam thresher there is the engineer, a fixed 



