591 series

The 591 series was an experimental Japanese dual-voltage tilting electric multiple unit operated by the Japanese National Railways from March 1970 to March 1973.
==History==
The 591 series was designed in 1967 to be a train that could increase speeds on curved sections of various lines; this was during a time when railway companies like Odakyu Electric Railway were experimenting with tilting trains. Kawasaki Heavy Industries would build a single experimental set in 1970; it was constructed in three articulated sections designated Mc1, M2 and Mc3, with all three sections treated as a single car designated KuMoHa 591-1.
KuMoHa 591-1 entered service on 27 March 1970; it was first used on the Tōhoku Main Line and stationed at Sendai General Rolling Stock Center. From April to June 1970, KuMoHa 591-1 was given basic performance tests with various factors, such as having the tilting mechanisms disabled and to determine the speed at which the set could go around corners with tilting enabled. More curve and straight line speed tests were conducted in May and July 1970 despite the enactment of the Nationwide Shinkansen Railway Development Act in May. Adhesion brake tests were conducted in October 1970 while curve and straight line speed was increased further; at this point the train was capable of going 135 km/h (84 mph) on straights and 35 km/h (22 mph) faster than normal on curves. Two more tests were conducted from 25 to 27 November 1970, where KuMoHa 591-1 was used on a long-distance test between Ueno and Sendai; the test on 25 November was a preliminary test with a 125 km/h (78 mph) maximum speed and 5 km/h (3 mph) higher speed on curves, while the actual test conducted on 27 November was conducted while other commercial trains were running, with a 130 km/h (81 mph) maximum speed and a 20 km/h (12 mph) higher speed on curves. Despite stopping at eight stations KuMoHa 591-1 completed the 351.8 km (218.6 mi) journey in 3 hours 39 minutes, 14 minutes faster than the Hibari services at the time. Stationary tilting tests were also conducted at Kōriyama Works. Notably on the day of the preliminary November test, the decision to begin construction on the Tōhoku Shinkansen was made.
Additional tests were scheduled in September 1970 with KuMoHa 591-1 coupled between either a 455 or 483 series set to check how multiple articulated trains would behave if mass production occurred but these tests were not carried out. Snow resistance tests were carried out in January 1971 with a maximum speed of 135 km/h on straight sections and 35 km/h faster on curves. In February 1971, tests on ergonomics and equipment were conducted, such as evaluating driver's cab height and equipment layout and stationary tests to see how KuMoHa 591-1 would react in the event of a main transformer surge. Also in February 1971, KuMoHa 591-1 was sent to Kōriyama Works to be rebuilt into a two-car tilting train without shared bogies due to test results showing that this configurations would ease stress on the bogies and reduce wear and tear; the M2 car was scrapped as a result of the modifications and the two remaining cars, Mc1 and Mc3, were extended in length and renumbered KuMoHa 591-1 and KuMoHa 590-1. The conversion cost ¥5,840,560 and was completed by the same month.
As this was the first time railcars were extended in length in Japan, preliminary tests were conducted by Kōriyama Works and the Railway Technology Research Institute to determine the cars's structural integrity; although the corners of each car were found to produce higher values than expected during vertical bend tests, there were no other issues of note and the car corners were reinforced as a result. KuMoHa 591-1 left Kōriyama Works on 31 March 1971 to resume testing. Much of the testing procedures remained the same as before the set was modified, such as high-speed and cornering tests, although "special tests" were also conducted on the set involving new axle boxes. With construction starting on the Tōhoku Shinkansen, it was determined that introducing tilting trains onto the Tōhoku Main line would be less cost-effective and new locations were scouted to test KuMoHa 591-1; in November 1971 KuMoHa 591-1 was moved to Nagano General Rolling Stock Center, where it underwent high-speed tests on the Shin'etsu Main Line.
Further snow resistance tests were conducted between January and February 1972 on the Shin'etsu Main Line, before the set was moved for use on the Kagoshima Main Line for tests the same month to explore the possibility of increasing speeds on heavier rails. In May 1972, JNR's "Speed ​​Investigation Committee" committee had determined that it could increase speeds using tilting railcars, following a decision to mass produce tilting railcars for use on curvy lines to increase train speeds to allow them to compete with highways. Throughout the remainder of 1972, KuMoHa 591-1 was used to collect data for use by the JNR to develop a tilting train for mass production, with tests conducted on the Shin'etsu and Chūō Main Lines through to 8 March 1973. The results gathered from testing would be used to develop and produce the 381 series sets, the first tilting trains on the JNR network.
Following these tests, KuMoHa 591-1 was stored at Okaya Station. Around this time, the KiHa 391 series articulated gas turbine railcar would also finish its tests, also intended to gather data for a mass-production gas turbine railcar; sometime the same year the concept of a mass-production gas turbine railcar was changed from an articulated train to a two-car non-articulated set due to a number of problems that arose with KiHa 391-1's construction mainly arising from it being articulated. As a result, a plan was drawn up to convert KuMoHa 591-1 into a gas turbine railcar. This conversion was partially completed, with KuMoHa 591-1 and KuMoHa 590-1 redesignated as Mc and Tc respectively and a Kawasaki KGR1400 gas turbine and the associated cooling and exhaust equipment installed in the underfloor of KuMoHa 591-1; the outbreak of the Yom Kippur War in October 1973 however caused an oil crisis, resulting in rising oil prices and leading to any sort of gas turbine railcars becoming uneconomical. With this in mind JNR decided to electrify the Hakubi and Tazawako Lines and the gas turbine testing program was unofficially canceled, with KuMoHa 591-1 remaining stored at Okaya Station, not to run again. The set was struck from the JNR roster on 26 March 1980, removed from Okaya Station and scrapped at Nagano Works the same year.
A DT96 bogie from KuMoHa 591-1 was preserved at the Modern Transportation Museum in Minato-ku, Osaka until its closure in 2014 and is currently unaccounted for.
==Design==
Externally the 591 series featured two different designs for its cab cars; Mc1 featured a flat front appearance reminiscent of rapid transit trains while Mc3 featured a high-mounted cab with two large headlights, taillights and automatic horn ports. The basic design of Mc3 would be adapted into the basic high-cab limited express electric trainset design used by the JNR throughout much of the 1970s, starting with the 183 series and 381 series, from which the results from the testing of the 591 series were used to design the sets's fundamentals.
==Specifications==
KuMoHa 591-1 was initially comprised of three articulated sections (Mc1, M2, Mc3) mounted on a set of shared bogies; all three sections could not be separated without the use of specialist equipment, with all three articulated sections treated as a single car. Following its rebuild the middle section marked M2 was scrapped and the set became a two-car non-articulated set with separate bogies for each car.
All three sections were fitted with seats. Mc1 has a flat front design, seats 48 passengers and is placed on the Tokyo-facing side of the Tōhoku Main Line; passenger doors are situated on the end of the car as well as an equipment room. The train's main control unit, resistor and chopper-based traction systems, motor-generator unit, air compressors, onboard batteries and air conditioning units are mounted under the floor. M2 seats 24 passengers; no doors are present on the outside of the cars for boarding or alighting, with this section only accessible from the other two cars. Two sets of toilets and wash basins are mounted on the Sendai/Aomori-facing side of M2. M2 is fitted with a pneumatically-actuated lozenge-type pantograph and is fitted with air conditioning units, water tank and sewage treatment tanks under the floor; no electrical equipment is present. Mc3 features a high cab design, also seats 48 passengers and is placed on the Sendai/Aomori-facing side of the Tōhoku Main Line; similar to Mc1 passenger doors are situated on the end of the car although unlike Mc1 there is no equipment room. Mc1 is mounted with a fixed lozenge-type pantograph and is fitted with the main transformer and rectifier, extra high-voltage equipment box, main control unit, main resistor, main braking unit and air conditioning units.
Each cab car featured a mounting slot which could mount a plaque; the plaque would most commonly read "Tilting Train KuMoHa 591". "High Speed KuMoHa 591", "High Speed on Curves" or "Test Running by Kawasaki Heavy Industries" were other sayings that could be present on the plaque. Mc1's mounting slot was located above the right headlight fixture while Mc3's was in the middle of the car's front.
==Preservation==
The following 591 series cars were preserved in the past but have since been scrapped:
Car number 	Manufacturer 	Date manufactured	Date retired	Previous sets	Last location 	Notes
KuMoHa 591-1	Kawasaki Heavy Industries	March 1970 	March 1973 	KuMoHa 591-1 	Okaya Station, Nagano, Japan	Complete two-car set, scrapped 1980
KuMoHa 590-1	Kawasaki Heavy Industries	March 1970 	March 1973 	KuMoHa 591-1 	Okaya Station, Nagano, Japan	Complete two-car set, scrapped 1980
==Gallery==
591 Okaya.jpg|Gangwayed cab end
==References==
Category:Tilting trainsets
Category:Unique locomotives
Category:Electric trainsets
Category:Kawasaki locomotives
Category:Prototype locomotives
Category:Scrapped locomotives
Category:Built in 1970
Category:Experimental locomotives