. Railway and locomotive engineering : a practical journal of railway motive power and rolling stock . nsider train shown by Figs. 2 and 3 are re-liable and conservative. Many times/luick calculations are all that are neces-sary and a few values are well to know or are available for handy reference sothat the results can be obtained approxi-mately without a careful check and ref-erence to the resistance curves. Theseare as follows: Electric locomotives, 15lbs. per ton and trailing load for freight ^ 2 1 CU i 2 w^ 0=10 / // V \ 2 ^ ^ / / > 1 0 ^ ^ //, y X > ? ^ ^0 ^ >
. Railway and locomotive engineering : a practical journal of railway motive power and rolling stock . nsider train shown by Figs. 2 and 3 are re-liable and conservative. Many times/luick calculations are all that are neces-sary and a few values are well to know or are available for handy reference sothat the results can be obtained approxi-mately without a careful check and ref-erence to the resistance curves. Theseare as follows: Electric locomotives, 15lbs. per ton and trailing load for freight ^ 2 1 CU i 2 w^ 0=10 / // V \ 2 ^ ^ / / > 1 0 ^ ^ //, y X > ? ^ ^0 ^ >> 500 1000 1500 2000 WEIGHT OF TRAIN IN TONS FIG. 2.—TRAIN CURVES FOR TRAINS IIP TO 400 TONS, AND SPEEDS IP TO 60 MILES PER HOUR. service at 6 to 7 lbs. per ton, up to aspeed of 30 m. p. h. Having the train resistance available inthe form of curves, the first part of thespeed time curve to be analyzed is the ac-celeration. The rate of change in velocityis the acceleration. The force necessaryto produce it is proportional to the pro-. 0 50 100 200 300 400 WEIGHT Of TRAIN IM TONS FIG. 3.—TRAIN RESISTANCE CURVES FOR TRAINS UP TO 2,000 TONS, AND SPEEDS UP TO 60 MILES PER HOUR. duct of the mass and the rate of theacceleration, i. e., WX A F = where = Weight of the body in = Rate of acceleration in feet perhour per second. [This value is for 1 mile per hourper sec. accel.] To see what this is for one ton we willuse 2,000 lbs. for W and for A andwill obtain a value of lbs. for this value is the tractive effort perton required to obtain rectilinear accelera-tion at the rate of 1 m. p. h. p. s., it doesnot take into consideration rotation ofwheels, armatures, etc., so that an addi-tional force is necessary, and to producethe 1 m. p. h. p. s. rate of acceleration avalue of 100 lbs. per tons is taken. Pro-portional values are used for differentrates; for instance, for IJ^ m. p. h. p. s.,150 lbs.; for J4 m. p. h. p. s., 75 lbs. We have
Size: 1427px × 1751px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidrailwaylocom, bookyear1901
