What kinds of bogies (trucks) are used by IR’s locomotives?

June 20, 2019, 11:44 AM
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For mainline BG locomotives, there were, until the 1980s, two main alternatives. The venerable WDM-2 which existed (exists) in vast numbers, along with the WDS-6, WAM-4, WAG-5, and some of the WCAM-1/2 locos used an Alco design asymmetric trimount (Co-Co) cast bogie design. Most other mainline BG locos used some variant of the GM-EMD ‘Flexicoil’ design, starting with the ‘Mark 1’ version for the WAP-1 and WAP-4 locos as well as the EMD-designed WDM-4 locos (export model SD-24), and variants known as ‘Mark 2’ or ‘Mark II’, ‘Mark 3’, etc., for other electrics such as the WAP-3. These were all cast bogies. RDSO experimented a lot with the designs of these bogies, to improve top speed, ride characteristics, etc., so that many variations can be found. The Flexicoil model was originally designed by GM-EMD and used in the American SD-7 locomotive of the 1950s. The innovation of the Flexicoil design at the time it was introduced was the isolation of lateral vibration by a swing hanger.

ये भी पढ़े – अफगानिस्‍तान में कमजोर पड़ता तालिबानी दुर्ग, जानें- इसका क्‍या है भारत-पाक फैक्‍टर

A newer generation of the Flexicoil design was introduced later in the form of the ‘Mark 4’ (‘Mark IV’) model which had a fabricated bogie frame assembly. This was used for the WAP-6, WDP-3A, and some other classes. These bogies were supposed to work up to 160km/h but turned out to be unsuitable for Indian track conditions at such high speeds and were restricted to 105km/h or so after initial oscillation trials. WDP-3A locos are now allowed to run at 120km/h on select sections such as the Konkan Railway stretch and the WR trunk route. The Mark IV Flexicoil bogies have some adhesion-increasing characteristics and have a rated top speed of 140km/h. The WAP-7 and WAG-9 locos use an ABB freight bogie design and have been tested and approved for speeds up to 140km/h.

Alco High-Adhesion bogies (which have a fabricated bogie assembly) were also introduced in the 1980s, and are used for the WDG-3A, WAG-7, WCAM-3, WDM-3D, WCAG-1, WCM-6, and other locos such as the Sri Lankan export model of the WDM-2. They are said to have several enhanced characteristics for providing high adhesion and good damping of vertical and lateral oscillations.

In addition there are some odd home-grown models of bogies such as the fabricated Bo-Bo bogies seen on the WDP-1 (based on a variant of the Flexicoil design) and WDM-6 locos. MG and NG locos have their own bogie designs, in most cases carried forward and adapted from the original imported loco models — there has not been a lot of active work at RDSO on developing new bogie designs for these narrower gauges.

Source – IFRCA.org

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