The class WDM-3A is Indian Railways' workhorse diesel-electric locomotive. Since 1993, it has been manufactured in India by the Diesel Locomotive Works (DLW), Varanasi. The model name stands for broad gauge (W), diesel (D), mixed traffic (M) engine. The WDM-3A is the most common diesel locomotive of Indian Railways. The WDM-3A is a later classification of earlier WDM-2C.[1] These units have been retro-fitted with dual brakes, in addition to the air and vacuum brakes. The WDM-3A locos have a maximum speed of 120 km/h (75 mph). The gear ratio is 65:18.[2]
The loco is now widely used across India for long distance passenger trains due to its ruggedness and high tractive loads and acceleration.
History
WDM3A VTA Shunting in RajkotA WDM-3A Loco from Gooty Loco Shed hauling an Express trainLocation map of the Diesel Locomotive Sheds of Indian RailwaysWDM 3D powerhouse of the Dehradun Shatabdi Express
The first one was delivered on August 22, 1994, It was then WDM-2C.[3] First 57 units produced till March 1996 (Indian Railway road number 14001-14057) had rounded front hood profile similar to contemporary newer classes of locos built by DLW (WDG3A and WDP1). After that there was a gap of long four years in the WDM3A production line in DLW. These new locomotives had their control stand shifted to the left side of the cabin. Meanwhile Diesel Loco Modernisation Works (earstwhile Diesel Modification Works which again was known as Diesel Component Works) in Patiala started rebuilding the existing WDM2 locomotives, which had reached midlife, with upgraded powerpacks. DLMW Patiala re-calibrates the powerpack and upgrades the output power rating to 3100HP.[4] DLW again started building WDM3A from the year 2000 and continued till the end of 2002 with locomotive road numbers in the range 14058-14143. All the locomotives rebuilt by DLMW and later batch from DLW had regular WDM2 type square short hood profile and control stand position. DLW again built WDM3A variant locomotives, during 2005-2006, in the road number range 14144-14167 which were classified as WDM3B due to their difference in bogie design from classic ALCo asymmetrical trimount to HAHS design which was employed in WDG2 and later WDM3D classes too. Most of the WDM3B were later converted to WDM3D. In 2011, DLMW rebuilt locomotive number 16502 as WDM3A and equipped it with an Elctronic Fuel Injection (EFI) system jointly developed by Engine Research Laboratory of IIT Kanpur, Engine Development Directorate of RDSO, and DLMW Patiala. [5] DLMW continues to rebuild WDM2 as WDM3A and recently they have started rebuilding the DLW built WDM3A too when they reach their midlife. Recent rebuilt locomotives are rated at 3300 HP, and from 2009 onward they are equipped with Daulat Ram DBR, and since 2014 they are also equipped with an Auxiliary Power Unit (APU) in the short hood.[6] Some rebuilt locomotives have Co-Co-fabricated ATHS (Advanced Trimount High Speed) bogies instead of ALCo cast-iron type. [7] All the rebuilt WDM3A bear the "-R" suffix to their road numbers.
In 2012 Bangladesh Railway ordered 26 WDM3A from DLW. They are classified as Class 6500 there. These units, however, lack the dynamic braking which happens to be an essential component in their Indian counterparts.
Sheds that hold WDM 3A
The following loco sheds have stabled this locomotive type:[8]
Alco 251-C, 16 cylinder, 3,300 hp (2,500 kW), earlier 3,100 hp (2,300 kW) (3,007 hp or 2,242 kW site rating, earlier 2,900 hp (2,200 kW)) with Napier NA2951R/ ABB VTC-304-VG15/ GE 7s 1716 turbo supercharged engine. 1,050 rpm max, 400 rpm idle; 228.6 mm × 266.7 mm (9.00 in × 10.50 in) bore x stroke; compression ratio 12.5:1. Direct fuel injection, centrifugal pump cooling system (2,457 L/min (540 imp gal/min; 649 US gal/min) at 1,050 rpm), fan driven by eddy current clutch (90 hp or 67 kW at 1,050 rpm)
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