3io 



THE POPULAR SCIENCE MONTHLY 



The Truck Loaded with Weights. 



to be standardized on a master scale 

 of the capacity of the car. Also since 

 the wheels, brake shoes, air brake con- 

 nections, etc., are part of the standard 

 weight such a car must be constantly 

 checked on the master scale. This 

 equipment is satisfactory for a rail- 

 road where the hauls from the master 

 scale to the scales to be tested is not 

 great, or where the operations are re- 

 stricted to a single state, but plainly 

 such an equipment would not answer 

 the purpose of the bureau since it ex- 

 pects to send the car to all parts of the 

 country, and it would not be possible 

 to establish the necessary master 

 scales at enough points to insure the 

 correctness of the test ear. The car of 

 the bureau was therefore designed to 

 reduce the wear on the equipment to a 

 minimum, and this is accomplished by 

 carrying a specially built, short, six- 

 wheeled truck, and 100,000 pounds of 

 standard weights inside a box car 

 which is equipped with the necessary 

 power to operate a crane for handling 

 the truck and test weights. The test 

 weights consist of eight 10,000-pouud, 



| four 2.500-pound weights and ten thou- 

 sand pounds of 50-pound weights. The 

 total error of the eight 10,000- and 

 the four 2,500-pound weights, is less 

 than half a pound and since the large 



j weights are bolted down to the floor of 

 the car in shipment from one scale to 



j another and are very carefully handled 

 when used, there is no reason why they 

 should change appreciably in a year. 

 The same is practically true of the 

 truck, which may, in a test of a 52-ft. 

 scale with three different loads, travel 

 about 300 feet or about sixty miles in 

 testing 1,000 scales. As this travel 

 would be at a very low speed, and with- 

 out the application of brakes or the ac- 

 cumulation of dust or mud, it is hardly 

 conceivable that its weight will change 

 as much as five pounds in a year, an 

 amount that would be insignificant in 

 the combined weight of the truck and 

 test weights. The truck which is 

 operated by an electric motor supplied 

 with current from a gasoline engine 

 generator in the box car weighs 5,059 

 pounds. 



Fig. 1 shows the general arrangement 



