2.18. FIRST DIVISION NDT

The first step in determining the NDT for the first division is

to find the starting tractive effort of the locomotives you have.

a. Tractive effort. Table. I shows that the 0660, 127ton

dieselelectric locomotive has a starting tractive effort of 75, 700

pounds. The continuous tractive effort for this locomotive is 50

percent of its starting tractive effort, or 37,850 pounds. Your

second step is to find drawbar pull.

b. Drawbar pull. The locomotives weigh 127 short tons each.

Subtract 20 pounds per ton of total locomotive weight from the

continuous tractive effort and you have the drawbar pull of each

locomotive:

20 x 127 = 2,540

37,850 2,540 = 35,310 DBP

c. Gross trailing load. The third step is to find the gross

trailing load for the locomotives. To use the formula for GTL

presented in paragraph 2.10, you must find the values for each

unknown. You already have a value for DBP; therefore, concentrate on

weather, rolling resistance, grade resistance, and curve resistance.

The process for finding values for each of these follows in the order

mentioned.

(1) Weather. Using table III and the information given on the

first division, you find that the loss in hauling power between 0

and +15 F. is 10 percent; therefore, the value for the weather factor

(W) is 0.90.

(2) Rolling resistance. Since the track for the first division

is rated good to fair, table II shows that a value of 6 should be

used for rolling resistance (RR).

(3) Grade resistance. Multiply 20 pounds per ton of train by

the percent of ruling grade for this division (1.5) and you find that

the value for grade resistance (GR) is 30.

(4) Curve resistance. The ruling curve for this division is

2.5, which must be multiplied by 0.8 pounds per ton of train to get

the value for curve resistance (CR) of 2.

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