
The NS 3900 was a series of express steam locomotives of the Dutch Railways. The NS 3900 was the last express steam locomotive specifically designed for the Netherlands. The NS 4000 series was ordered in Sweden during the war, however this series was based on an existing Swedish design.
At the end of the 1920s, the Dutch Railways needed an express locomotive that was stronger than the 3700 series, because more and more wooden passenger coaches were replaced by steel ones. The axle load could also be increased from 16 to 18 t (17.6 to 19.8 short tons; 15.7 to 17.7 long tons). This resulted in a design that looked at both NS 3600 and NS 3700 series, so with a wheel arrangement of 2'C. The NS 3900 series used bar frame of the 3600 but the design of boiler, cylinders and cab resembled the 3700 series, but with a more powerful boiler and cylinders with a diameter of 420 mm (16.5 in) instead of 400 mm (15.7 in). This increased tractive effort by about 15 percent. The same boiler would later be used on the 6300 series of tank engines. The tender was similar to that of the NS 3600 series and the later built eight wheeled tenders of the series 3700 series. The NS 3900 was able to quickly bring the heaviest passenger trains to a speed of 100 km/h (62 mph).[1]
The manufacturer, Henschel & Sohn, built the locomotives in two batches in 1929 and 1930. The first batch of 22 locomotives from 1929 (3901-3922) was initially not built with smoke deflectors. These were installed in 1930. The second batch of ten locomotives (3923-3932) was fitted with smoke deflectors immediately upon completion.[1]
Until the electrification they pulled the heaviest express and D trains, but there were also disadvantages. The 3900 or 6300 classes could not be fired by hand and the power output of 1,600 kgf (3,500 lbf) was only achieved with the best coal and a good fireman. The locomotives were also technically unsuccessful. The boiler design was old-fashioned and the cylinders and valves were also of an outdated design. The build quality was also poor, which resulted in cracking inner fireboxes and disproportionate wear of various sliding bearings of the cylinder block.[2]
運用開始後すぐに、3900形機関車の品質をめぐって論争が巻き起こった。石炭消費量以外は、6300形には上記のような欠点が全く見られなかったことから、この論争は裏付けられた。様々な委員会の調査結果に基づき、機関車の構造に調整が加えられ、問題はほぼ解決された。しかし、何度かテストを行ったにもかかわらず、このシリーズの蒸気性能の悪さは廃車まで続いた。これは、シリンダーブロックの構造に一部起因しており、大規模な改造にはシリンダーブロックの完全な交換が必要となることが多かった。コストが高額なため、3900形シリーズではそのようなことは行われなかった。[ 2 ]
主要都市間の高速接続を提供する必要があった中央ネットワークで新型ディーゼル3編成列車に問題が発生したため、蒸気機関車が牽引する短距離急行列車であるいわゆる蒸気ディーゼルサービスに置き換えられました。この蒸気ディーゼルサービスは、ディーゼル多目的列車の時刻表に追随できる必要がありました。その前に、2100、3700、3900シリーズの機関車で最初のテスト走行が行われました。2100と3700はどちらも3900よりも速いことが判明しました。これは、3900が独自の転がり抵抗が高く、軽量急行列車にはあまり適していなかったためです。[ 2 ]
第二次世界大戦後、主要路線の電化が急速に進むにつれ、3900系は次第に使用されなくなり、主にまだ完全電化されていない路線の急行列車やD列車で使われるようになった。現存する車両はないが、保存されているNS 6317にはNS 3927のボイラーが搭載されている。