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 ED 103 at Ferrymead | |||||||||||||||||
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TheNZR ED classlocomotive[nb 1] was a type ofelectric locomotive used inWellington,New Zealand. They were built byEnglish Electric and theNew Zealand Railways Department (NZR) between 1938 and 1940, and hauled mainly passenger trains on the Wellington region's 1500 V DCelectrification, and banked freight trains on the steep section betweenPaekākāriki andPukerua Bay.
The locomotives featured a unique wheel arrangement, 1-Do-2 under theUIC classification system, and incorporated aquill drive (the only type of locomotive to do so in New Zealand) to the driving wheels.[1]
They were found to be hard on the tracks, leading to speed restrictions on these locomotives and their replacement byEW class locomotives on theJohnsonville Line after the introduction of the EW class in 1952.[2] The EW class was considered more suited to passenger services than the ED and replaced them on most passenger services on other lines.[3]
Like all other electric locomotives in New Zealand, the leading letter of the locomotive's classification is E. There are two predominant theories about how the ED class acquired the second letter, D. The first is that it comes from the "Do" of its 1-Do-2 wheel arrangement. The second is from its original allocation to two locations, Wellington and Otira - Arthur's Pass, hence "duplicated". Official records do not confirm either theory.[4]
New Zealand Railways purchased one ED class locomotive in 1938 from English Electric, No. 101, for use on the newly openedTawa Flat deviation, which incorporated two long tunnels. This locomotive was known as "The Sergeant" because of the three longitudinal stripes on each side of the body that were unique to this locomotive.[5]
The tender required the supply of locomotive components for the other locomotives required, as it was thought desirable to carry out manufacture in New Zealand in NZR workshops. A further seven locomotives were assembled at theHutt Workshops, and two atAddington Workshops for use on theOtira -Arthur's Pass section of theMidland Line.
The first locomotive was shipped to New Zealand in January 1938.[6] The first locomotive assembled at the Hutt Workshops was completed and undergoing trials in May 1939.[7][8]
By December 1939 the assembly of four locomotives at the Hutt Workshops had been completed, and they were expected to be operating to Paekakariki early in the new year.[9][10]
The changeover was done gradually, and by July 1940 19 of 20 suburban trains were electric loco-hauled.[11][12] By September 1940 they were hauling most trains, releasing most of the KA class locomotives at Wellington for use elsewhere.[13]
The two South Island locomotives were transferred north to Wellington in 1943. Their cast iron headstocks could not withstand the shock of shunting, and they could not dissipate the heat generated by rheostatic braking (although in Wellington air brakes were adequate).[14]
With the introduction of theTraffic Monitoring System (TMS) in 1979, the two remaining locomotives were renumbered ED15 and ED21.[15]
Each locomotive (ED 101 to ED 108; not ED 109 and ED 110) originally hadoil-fired water-tube boilers for passenger carriage steam heaters, supplied by theSentinel Waggon Works.[2] The boiler could supply 1,250 pounds (570 kg) of steam per hour at a pressure of 40 pounds per square inch (280 kPa), and the water and oil tanks had capacities of 400 and 500 imperial gallons (1,800 and 2,300 L) respectively, so could steam for four hours before refilling.[16] They were shut down or removed in 1950 due to "ongoing reliability problems"; air turbulence particularly in tunnels or when trains passed on double-track sections resulted in downdraughts affecting the boiler and in passenger discomfort in winter. In June 1951 the Deputy Mechanical Engineer said that the cost of fitting suitable boilers for the section from Paekākāriki to Wellington was not warranted as the carriages leaving Paekākāriki had residual heat, and a steam loco could pre-heat carriages before they left Wellington. In 1954-55 two boilers were installed in the Wellington station basement (and in 1958 one went to the NZR Road Services garage in Rotorua). The Chief Mechanical Engineer then wanted eight locos to have boilers for the 1955 winter, but parts were not available for the obsolete boilers and "refurbishing did not proceed". It was also found that the boilers were unreliable as the burners had been amended to be outside the normal operating specifications.[17]
With the introduction ofDA class diesel locomotives on the Paekākāriki via Pukerua Bay to Wellington electrified section in 1967, eight of the class were withdrawn from service in 1969 and scrapped.[18] The remaining two were kept in sporadic service until March 1981, when both locomotives were sold into preservation. There were plans to send them back to the Otira - Arthurs Pass section, but nothing came of this. ED 101 is preserved by theSilver Stream Railway, while ED 103 is preserved by theCanterbury Railway Society.
A porter-shunter at Johnsonville was accidentally killed in March 1940 when he stepped into the path of a train being shunted by an ED locomotive.[19]
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