70 
BULLETIX 1348, U. S. DEPAETMEXT OF AGRICrLTXTlE 
Table XX. — Approximate average cost per drawbar horsepower-hour for gas 
tractor power in 1924 ^ 
First cost per drawbar horsepower $75. 00 
Average equivalent drawbar horsepower-hours, developed annually, 265. 
Annual interest at 8 per cent on average investment 3. 20 
Annual depreciation and repair charge due to age at 8 per cent 6. 00 
Housing, taxes, and insurance per year 2. 00 
Total fixed charges per year per drawbar horsepower 11. 20 
Depreciation per horsepower-hour chargeable to use . 023 
Cost of fuel, oil, and care per horsepower-hour . 041 
Cost of repairs and labor per horsepower-hour .019 
Total operating costs per drawbar horsepower . 083 
Net cost per drawbar horsepower-hour and per year, including both operatijig and 
fixed charges for various amounts of power developed annually 
Horse- 
K^" .^^ Operating 
deve^ed ! charges per charges per 
per drawbar \ "^"^ """^ 
horsepower | 
Total 
cost per 
horsepower- 
hour 
Total cost 
per year per 
drawbar 
horsepower 
50 
$0,224 ! $0,083 
.112 .083 
.056 .083 
.037 .083 
.028 .083 
.022 ' .083 
.019 .083 
$0,307 
.195 
.139 
.120 
.111 
.105 
.102 
$15.35 
19.50 
27.80 
36.00 
4140 
52.50 
61.20 
100 
200 
300 
400 
500 
600 
700 
800 
1,000 
2,000 
3,000 
.016 
.014 
.011 
.006 
.004 
.083 
.083 
.083 
.083 
.083 
.099 
.097 
.094 
.089 
.087 
69.30 
77.60 
94.00 
178.00 
261.00 
1 Does not include wages for operator while tractor is in use, but does include an allowance for care and 
for time required in putting in fuel and for greasing. 
Wages for the operator were excluded in these computations because they vary indirectly with the size 
of unit used and also because in some operations much of the time of the operator is devoted to manipulating 
the machinery used rather than caring for the power unit. 
