Haupt. ] 1 0 [Jan. 20 
Placing these two values of R equal to each other, 
there results  Wla W*b—W'a 
wW-wi Wwe 
By substituting in the equation the values of W' W2 a and b, as deter_ 
mined by observation, the values of W, or the gross load on a level can 
be ascertained. 
By substituting the values of W W' W2a and b, the value of R on the 
power exerted by the engine is obtained. 
By dividing this power in pounds by the gross load on a level, the trac- 
tile power per ton is determined. 
As the power of an engine is always sufficient to slip the wheels ona 
dry rail, the adhesion is equal to the actual power exerted in moving the 
train and divided by the weight on drives, gives the proportion between 
adhesion and weight. 
‘rhe angle of friction can be found when the tractive power per ton of 
of 2000 Ibs. on a level (T) has been determined, by the equation. 
T X 5280 
2000. 
It has been customary for engineers to consider the angle of friction as 
16 to 18 feet per mile, the tractive power per ton on a level 8 pounds, and 
the adhesion one-eighth the weight upon the drives; but to obtain reliable 
data from the actual operation of roads running full trains, a letter was 
addressed to A. J. Cassatt, Gen’l Sup’t of the Penna. R. R., who fur- 
nished the following data: 
A standard 10 wheel freight engine with 3 pairs of 4} feet drivers with 
Angle of friction expressed in feet per mile = 
average water and coal, weighs 75,500 lbs. 
Weight on drivers, 58,000 ‘< 
Weight of tender with coal and water, 50,000 ‘* 
Such an engine will haul on a moderately straight and Jevel road 50 
loaded ears of 40,000 lbs. each. Gross load, 1062 tons. 
On a grade of 10 feet to the mile, 48 cars, O82,05 < 
a6 “ce 26 “6 “ec ce 85 oe 762 ee 
oe ce 52455 “se “e abhe se 402 “ec 
“ec 6é 96 46 oe “é 11 “ce 282, “e 
And the engine would work easier with 50 cars on the level than in either 
of the other cases and with most difficulty in the last. 
Herman J. Lombaert, Esq., Vice President and former General Super- 
intendent of Penna. R. R., gives as a full average load for actual work in 
the usual conditions of the rail. 
Tons. 
Load on 528, ft. grade, 16 cars. Gross load of engine, 382 
6c 6é 10 6s 6é AQ “e “ce 66 66 862 
As it is proper to allow a margin for unfavorable condition of rails, the 
calculations will be made on the data furnished by H. J. Lombaert. 
Substituting the values of a b W! W2, which are 10, 5258, 882 and 862, 
the value of W, or the gross load on a Icvel is found be 1210 tons. 
