Japan Railways locomotive numbering and classification
This page explains the numbering and classification schemes for locomotives employed by the Japanese Government Railways, the Japanese National Railways and the Japan Railways Group. Steam locomotives. Pre-nationalization. Prior to the nationalization of Japanese railways in 1906 and 1907, the government-run railways had numbered their steam locomotives only with serial numbers without consideration of the types of the locomotives. From the beginning of the Kobe–Osaka railway in 1874, they allocated odd numbers to locomotives in Tokyo area and even numbers to locomotives in Kobe area, but this custom was not maintained  after the completion of railway between Tokyo and Kobe in 1889. Later, some locomotives, such as Classes A8 and B6 and rack railway locomotives, were renumbered to make groups for easy recognition of classes. Classes were introduced by Francis H. Trevithick (1850–1931), a grandson of Richard Trevithick, employed by the government of Japan for supervision of rolling stock management. He classified the locomotives with one Latin letter (A through Z), which was then expanded to use two letters (AB, AC, AD, and so on). Later, this simple method was revised to use one letter and one or two digit numerals  with consideration of locomotive types. The meanings of the letters were as follows: 1909 numbering system. Following the railway nationalization, in 1909, the railway authority adopted a new system in which locomotives were numbered and classified by four-digit numerals. All existing locomotives were reclassified. Numbers 1 through 4999 were allocated for tank locomotives and 5000 through 9999 were allocated for tender locomotives. Here the classes and the numbers acquired a distinct relationship. Locomotives were grouped in numbers and the classes were represented by the earliest number of the group. Numbers within a class were serial in principle. When the  number overflowed (as in Classes 8620, 9600 and 9900), one digit was added to precede the four digits to make the numbers five digit. Class 18900 (later reclassified as Class C51) was exceptionally five digit from the beginning. This numbering and classification rule survived the revision in 1928. Non-standard locomotives that joined the national railways by means of purchase of railway companies were numbered in accordance with this rule even after 1928. Locomotives numbered and classified under this rule includes the locomotives used until very last days of JNR steam locomotives in the 1970s. 1928 numbering system. Because the  1909 method was about to overflow, a new system of numbering and classification came into effect on October 1, 1928. Except for Classes 18900, 8200 and 9900 being reclassified as C51, C52 and D50 respectively, existing locomotives were not reclassified or renumbered. After this revision, steam locomotives were classified and numbered with a Latin letter and numerals. Unlike electric and diesel locomotives, steam locomotive classifications do not include an indication of the type of power source (steam) in their class names. According to this numbering method, D51 498 means locomotive number 498 of Class D51, which is a class of  tender locomotives with four driving axles. Electric locomotives. Pre-1928 numbering system. The national railways imported its first electric locomotives in 1912. Like steam locomotives of that period, electric locomotives were numbered with four or five digit numerals. Classes were represented by their earliest numbers, last digit being "0". The table below lists all classes of the electric locomotives identified under this method. 1928 numbering system. A new system of numbering and classification came into effect in 1928. Originally, electric locomotives were classified by maximum speeds. High-speed locomotives were for passenger trains and low-speed locomotives were for freight trains . Later, the system was revised to distinguish the types of electricity when AC and AC/DC locomotives were introduced. According to this numbering method, EF81 95 means locomotive number 95 of Class EF81, which is a class of AC/DC locomotive with six driving axles and maximum speed exceeding 85 km/h. JR Freight. Out of seven Japan Railways Group (JR Group) companies established in 1987, only Japan Freight Railway Company (JR Freight) has built new electric locomotives. Initially JR Freight continued to build locomotives originally designed by JNR with minor modifications. However, in 1990, it created the new class  of EF200, adopting a new classification system with three-digit class names. This system was also later adopted by East Japan Railway Company (JR East) when it introduced its version of the Class EF510 in 2010. Usage of Roman letters is the same as the 1928 rule. A hyphen is placed between the class number and running number. According to this numbering method, EH500-31 means locomotive number 31 of Class EH500, which is a class of AC/DC locomotive with eight driving axles and AC motors. Diesel locomotives. JNR. The history of diesel locomotives of the Japanese Government Railways  started with two classes of German-made locomotives, the diesel-electric Class DC11 in 1929 and the diesel-mechanical DC10 in 1930. The Ministry of Railways numbered them in accordance with the similar system as it then used for steam and electric locomotives. The Japanese National Railways continued with this system. According to this numbering method, DD13 1 means locomotive number 1 of Class DD13, which is a class of diesel locomotive with four driving axles and maximum speed 85 km/h or less. JR Freight. After the privatization of JNR in 1987, two Japan Railways Group (JR Group) companies  created new classes of diesel locomotives. East Japan Railway Company (JR East) classified its new class as DD19, using the JNR classification system, as it was only a rebuild of the Class DD17, which was built by JNR. On the other hand, Japan Freight Railway Company (JR Freight) built completely new diesel locomotives, which were classified using a new system with three-digit class names. Usage of Roman letters is the same as for JNR usage. A hyphen is placed between the class number and running number. According to this numbering method, DF200-7 means locomotive number 7 of Class  DF200, which is a class of diesel-electric locomotive with six driving axles and AC electric motors. Shinkansen. Diesel locomotives used on the Shinkansen system (for track maintenance and depot use) are numbered with three-digit class names followed by a serial number connected with a hyphen. There have been two classes of diesel locomotives for shinkansen use: 911 and 912. In the uniform classification system for Shinkansen rolling stock, the first digit 9 is assigned for cars and locomotives for departmental use. In this 9XX group, the second digit 1 is used for diesel locomotives. Hybrid locomotives. In 2010 , JR Freight classified its first diesel-battery hybrid locomotive HD300. The class name HD300 was explained as follows.