18 ton axle load 2000 hp (equivalent to a class L locomotive) - either 2-8-2 or 4-6-4 wheel arrangement with 18 ton axle load 1500 hp (equivalent to a class Su locomotive) - either 4-6-2 or 2-6-4 wheel arrangement with 18 ton axle load After analyzing the various proposals, VNIIZhT workers concluded that a 4-8-4 locomotive producing 3000 hp would meet requested performance characteristics, but as a locomotive with 18-ton axle loading was needed, in 1947 Kolomna Works was given orders to design and produce a 4-8-4 with 18-ton axle loading. The design team was led by L. S. Lebedyanskiy and included engineers GA Zhilin and I. Sulimtsevym among others. Prototype locomotive In March 1950 the prototype locomotive, P36-0001, was completed at Kolomna. It employed all of the latest technology in Soviet locomotive construction including a welded boiler, mechanical stoker, power reverse, cast frame, and roller bearings on all engine and tender axles. The locomotive was tested on the October Railway, based out of Moscow, where it was tested severely including pulling freight trains on passenger train schedules. Results proved to be positive, with the locomotive typically developing 2500–2600 hp or as high as 3077 hp at 86.4 km/h. Thermal efficiency was 9.22%, the highest of any Soviet passenger locomotive and only .05% lower than the class LV. Production locomotives Since the test results were positive, Kolomna Works was given an order for a small batch of prototype locomotives. In 1953 four more locomotives were built, numbered 0002–0005, and in 1954 another locomotive numbered 0006 was constructed. Some changes were made to the design of the axle boxes, shoes and wedges; the smoke box blower utilized on the first prototype was dispensed with; and the decorative streamlining panels were simplified. Numbers 0003 and 0004 were sent to the Moscow-Kursk line for testing, while 0002 and 0005 were tested at Krasnoyarsk and 0006 was tested on the test track at VNIIZhT. The initial batch of 30 production locomotives numbered 0007–0036 was produced in 1954, including small changes made from the prototypes. At the end of the year the P36 type was approved for mass production, and in 1955 Kolomna Works produced 155 locomotives numbered 0037–0161, followed by another 90 built in 1956 (0162–0251). Over the course of production minor changes were made to the design. However almost as soon as it was begun, production was curtailed. The reason was that in