ITM3579993 Weighbridge Test Wagon no 3453-Weighbridge test wagon Dept No

A scale test car is a type of

railroad car A railroad car, railcar (American English, American and Canadian English), railway wagon, railway carriage, railway truck, railwagon, railcarriage or railtruck (British English and International Union of Railways, UIC), also called a tra ...

maintenance of way Maintenance of way (commonly abbreviated to MOW, also known as "Permanent Way Maintenance" or "PWM" in Britain) refers to the maintenance, construction, and improvement of rail infrastructure, including tracks, ballast, grade, and lineside infras ...

service. Its purpose is to calibrate the

weighing scales A scale or balance is a device used to measure weight or mass. These are also known as mass scales, weight scales, mass balances, massometers, and weight balances. The traditional scale consists of two plates or bowls suspended at equal dis ...

used to weigh loaded railroad cars. Scale test cars are of a precisely known weight so that the track scale can be calibrated against them.

Purposes

Cars are weighed for various purposes. These include:

Axle load limits

Cars are weighed to ensure they are within the

axle load The axle load of a wheeled vehicle is the total weight bearing on the roadway for all wheels connected to a given axle. Axle load is an important design consideration in the engineering of roadways and railways, as both are designed to tolerate a m ...

limits of the railroad.

Customer billing

Cars are weighed to determine (by subtracting the car's unloaded, or

tare weight Tare weight , sometimes called unladen weight, is the weight of an empty vehicle or container. By subtracting tare weight from gross weight ( laden weight), one can determine the weight of the goods carried or contained (the net weight). Ety ...

from the total

weight In science and engineering, the weight of an object is a quantity associated with the gravitational force exerted on the object by other objects in its environment, although there is some variation and debate as to the exact definition. Some sta ...

) the amount of cargo loaded. This is used to bill the railroad's customers for the carriage of bulk commodities, so it is essential that the track scales be accurate.

Construction

Many scale test cars were small, old railroad cars carrying heavy metal weights as their superstructure. Scale test cars needed special handling so they would not suffer damage, which might alter their weight. They were reweighed periodically on accurate scales at the railroad's shops.

References

Bibliography

*AAR, Engineering Division, "AAR Scale Handbook (2011)" *USDA, AMS, Grain Inspection Packers and Stockyards Administration (GIPSA), "Weighing Handbook" ch. 3, pp. 31-34, 27 December 2010 (Overall Document dated: April 2014) Retrieved: 08 June 2020

External links

NIST The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical s ...

br>circa 1913 scale test car and its transporter rail car
One of its large calibration masses can be seen being hoisted onto the scale test car. Maintenance of way equipment Mass Measuring instruments {{Rail-transport-stub