WAM 4 - Father of the Nation for RailFans - Vikas Kumar

1) Naming diesel locomotives based on their power output, started only in 2002. Prior to that, the last digit in the locomotive class name represented the chronological order of the introduction of the locomotive. In 2002, the naming scheme was changed to represent the output power. But the WDP1 loco and all the shunters were exempt from the naming scheme. Since the WDM6 and the WDM7 are mainly used as shunters, they were not renamed.

For example, WDM1 was a BG, mixed-use diesel loco, and the first mainline diesel loco introcduced, hence...
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the suffix '1' at the end. Similarly, WDM2 was the second, WDM3 (NOT the present day WDM3A, WDM3 were a different class of locos homed only at Gooty in SCR) the third, WDM4 the fourth and so on.

In that sequence, WDM6 was the 6th mixed-use mainline diesel locomotive. It was designed in the early 1980's, long before the naming scheme was changed. So it was named thus.

2) It is rated at 1350HP. They were constructed by using the YDM4 (the main metre gauge diesel loco) powerpack on BG bogies.

3) They were intended to haul short commuter trains in suburban areas along with light shunting. Hence the WDM class. However, MEMU's and DEMU's quickly came around and did the job better than these locos. So these just handle shunting jobs now.

There are quite a few 6000+ HP diesel locos in the world. Both EMD and GE produced 6000+ HP locomotives for a long time and they were operated in the US. China too has operated high powered diesel locos.