The winch capacity (number of cars tha can be moved) can be approximated by considering the following factors*:

A (Starting Resistance)

=

25 lbs./ton of cargo for operation in ambient temperatures above freezing and up to 35 lbs./ton for operation below freezing.

B (Curve Resistance)

=

0.8 lbs./ton of cargo per degree of curvature.

C (Grade Resistance)

=

20 lbs./ton of cargo per percent of grade.

D (Track Condition)

=

0 lbs./ton of cargo for track in excellent condition to 10 or more lbs./ton for track in poor condition.

E (Condition of Railcar)

=

0 lbs./ton of cargo for a well maintained car to 10 or more lbs./ton for cars in poor condition.

Pulling capacity required per ton of cargo

=

A + B + C + D + E

N (Number of cars that can be moved)

=

Winch Capacity
(A + B + C + D + E)(Cargo tonnage per car)

 

EXAMPLE:

With the following conditions, how many 80-ton railcars can be moved?

  • Above freezing ambient temperature
  • 1℉
  • 1%
  • Good track conditions
  • Well maintained car

A + B + C + D + E = 25 lbs./tons + 0.8 lbs./ton + 20 lbs./ton + 0 lbs./ton = 45.8 lbs./ton

N = 22,000/(45.8)(80) = 6 railcars

If B, C, D and E are all 0, eleven 80-ton railcars can be moved.

*Factors are based on the average requirements given in the A.R.E.A Manual for Railway Engineering and on railcar pull tests conducted by NABRICO. These factors are only guidelines.