Indian locomotive class WDM-3D

The WDM3B diesel locomotive class was developed in 2005 after the WDM3C and WDM3D. It actually is a variant of the WDM3D, though it shares its power rating with the WDM3A. Only 23 numbers were built (road numbers #14144 to #14167), making them very rare. It has the same engine as the WDM3D, despite having a power deficit of 200 hp. It also looks the same, shares the same body shell, control cabin, undercarriage and the high-adhesion bolsterless bogies of the WDM3D. The difference is that unlike the WDM3D, the WDM3B is not microprocessor controlled but uses something called “E-Type Excitation” for locomotive control. The WDM3B seems to be the result of the Railways trying to cut the WDM3D down to size by eliminating its troublesome features like microprocessor control. But now 3Bs are being converted into 3Ds. WDM3Bs are housed at UP sheds like Lucknow, Gonda, Jhansi, Samastipur, Patratu etc. and many are (were) famously named “Gajraj”. The WDM3B does not adhere to the hp-based naming convention as WDM3A already represented 3100 hp. IR just assigned the vacant WDM3B class to this type.[6]

This was an experimental class developed out of the WDM3D by IR on the ever-lookout for more power, all equipped with High Adhesion bogies and roof-mounted DBRs. However, they never entered serial production. Some suggest that the WDM3E is actually called “WDM3D without Equalizer” or WDM3Ds with 3500 hp power. The known road numbers in service for this class are #11306 to #11311 and #11263. All are marked WDM3D and all are used to haul only freights with speed restricted to 85 km/h. They look exactly like the WDM3D and share all its features.[7]

A WDM-3B with KYQ - GIMB Express

The very extremely rare WDM3F was the result of the last and final experiment in IR's drive for more powerful ALCOs. This one is rated 3600 hp and only four were produced (#11287, #11321, #11325, #11342). #11287 has a unique aerodynamic design where the ends taper upwards (picture above). All WDM3Fs are based at Gooty (GY) and share all the features of the WDM3D including roof mounted DBRs except the #11287. Though high powered, this class apparently didn't work out well because after the WDM3F, IR realized that it is futile to try and crank more power of the ALCOs as they were too old and outdated and shifted attention to the EMD. This also marked the beginning of the end of the ALCO domination on Indian Railways.[8]

Ten WDM-3D locomotives were purchased by Sri Lanka Railways in 2012. They were the longest and most powerful locomotives owned by Sri Lanka Railways at that time. They were allocated the M10 class.[9] However some specifications are somewhat different for SLR.[10] This class was used for the construction work of Talaimannar and Kankasanthurei railway lines. After extending the northern line to Jaffna and beyond, M10s were used for passenger services including Yal Devi on the northern line. As of August 2020, all units of this class are still in service.

On 27 July 2020, due to over-aging of existing Bangladesh Railways locomotives, IR gave 10 WDM-3D units for free under its “grant assistance” plan. The Railways has modified the locos to suit the maximum height restrictions in BR and the donated locomotives (6-8 year old) have 28 years of serviceable life left. India formally handed over the locomotives in a virtual ceremony on July 27.[11][12] The vehicles cost an estimated ₹600m ($US 8m) to manufacture. [13] On 24 May 2023, 20 more WDM-3D locomotives were gifted under the same “grant assistance” plan.

• https://m.indiarailinfo.com/blog/post/1675425/3#1675425-3
• https://www.dlw.indianrailways.gov.in/works/uploads/File/WDM3D.pdf
• https://www.facebook.com/AlCoRedifined/posts/some-specification-of-wdm3d-the-future-workhorse-of-indian-railwaysgeneral-descr/310260822341396/
• http://traintrackers.org/misc/wdm3d.html Archived 20 June 2019 at the Wayback Machine