2-8-4 IS21 locomotives from Voroshilovgrad. The completed the last eleven in 1941 and 1942. Despite their moderate size compared to American and Canadian-built 2-8-4s, the Soviet 2-8-4 was a good example of a Berkshire type designed for heavy express and passenger train service. It had a grate, boiler pressure, boiler heating surface of which was superheated, and only 20 to 21 tons maximum axle load. Their diameter coupled wheels and cylinders of bore and stroke, with a total weight of 133 tonnes of which 80.7 tonnes were adhesive weight, enabled the locomotives to easily reach the maximum permitted speed of with
1/2 + 1/4 + 1/8 + 1/16 + ⋯ 1/2 + 1/4 + 1/8 + 1/16 + ⋯ In mathematics, the infinite series is an elementary example of a geometric series that converges absolutely. There are many different expressions that can be shown to be equivalent to the problem, such as the form: 2 + 2 + 2 + ... The sum of this series can be denoted in summation notation as: As with any infinite series, the infinite sum is defined to mean the limit of the sum of the first terms as approaches infinity. Multiplying by 2 reveals a useful relationship: Subtracting from both sides, As approaches