Section No. 1--General Rules (New-9-1984)
PROCEDURES FOR DETERMINING COMBINED CENTER
OF GRAVITY OF LOAD ON CAR ABOVE TOP
OF RAIL OF LOADED OPEN TOP CARS
The following information is necessary to determine the combined center of gravity of a loaded open top car.
A = Height of car deck from top of rail.
B = Center of gravity of car above top of rail, obtainable from car owner.
C = Center of gravity of load from base of load, obtainable from shipper.
D = Combined height of center of gravity of load, (C), plus height of car deck, (A), that is (C) + (A).
E = Lightweight of car, in pounds, as stenciled on car.
F = Weight of load, obtainable from shipper.
The calculation to arrive at the center of gravity is as follows:
(B x E) + (D x F) = Combined center of gravity above top of rail.
A = 44 inches
B = 27 inches
C = 60 inches
D = (60 + 44) = 104 inches
E = 55,000 Lbs.
F = 120,000 Lbs.
(B x E) + (D x F) + C. G. ATR
(27 x 55,000) + (104 x 120,000)
55,000 + 120,000
1,485,000 + 12,480.000 = 13,965,000 = 79.8 inches ATR
The above is an example of a basic calculation for determining the combined center of gravity of load and car.
Where the load consists of multiple piles or pieces with differing centers of gravity, the entire C.O. of the entire
load must be calculated before it is combined with the car weight and C.O.
Acceptable centers of gravity for interchange purposes are governed by Rule 89. Section B. 1, e of the Field
Manual of the AAR Interchange Rules.