wdmtribute3

This is my third part of the promised four part unfolding of the saga of the
WDM2.

Railway Enthusiasts whether they hate or love the diesel-electric locomotive
cannot just but have an awe for this great locomotive. Today I am supposed to talk a bit more on the technical side of the WDM2. The ALCO specification for WDM2 is DL560C and I found in a drivers handbook given on the NF Railway that it is of the model RSD 29 though it has lot of features similar to the famous Century series.

This similarity was pointed out in the ---GREAT BOOK OF TRAINS(1996)-- an
encyclopedaic work by Brian Hollingsworth and Abraham Cook regarding the
301-most popular locomotives of the world. Note that WDM2 finds a place
there. May be DL560C is the export version of RSD 29 for ALCo just as WDM4
is the export version of SD-24.

If one has a careful look at least at the wheel-set of the WDM2 one will find that it is very similar to that of the Century Class C628 series. These are the famous ALCO Co-Co Trimount bogies known to drivers all over for their rough ride. The Century series of locos were the last attempt by the great ALCO to ward off the competition from the all conquering GM-EMD. There were several railways in the USA who were a very devoted ALCO customer. The most devoted among them must be Delware and Hudson who brought hundreds of them followed by the romantic Leigh Valley Railway. These Century class were mighty movers and could bascically move everything. They were put into a lot of tests. Very recently a veteran railroader wrote in the in the Railroad Press magazine about his experience with Leigh Valley ALCOs. He mentions how the C628 class was put into all sorts of test including climbing steep grades without bankers and with a heavy coal train. The Centuries suceeded in all of them but unfortunately they had to give way to the superior SD-40-2. One of the main reason for removal of the Century Class was the damage that was inflicted to the tracks by those huge Co-Co Trimount trucks.

The WDM2 however lives on and infact the Co-Co trimount bogies became
popular in India and even used on electric traction like WAM4 and WAG5.

While I was at Kharagpur I was a frequent visitor to the System Technical
School of the S. E. Railway at Kharagpur. They had a very big model room depicting all the parts of the WDM2 including the drivers control stand ( To which I was more attacted naturally) and the electrical panel. The back panel of the electric panel had three interesting relays called the speed sensitive relays which used to read the speed from the voltage supplied by the axle generator and trigger the transition by changing the traction motors connections. The WDM2 has four
types of traction motor connections. They are

1. Series-parallel (2-in series by the each of the three blocks in parallel)
2. Series-Parellel shunted field (32 km/h)
3. Parallel (55kmh)
4. Parallel-shunted field.(81 kmh).

So with four types of connection one needs three transitions and thus we have three speed sensitive relays. These relays are now replaced by the BX/BX electronc cards and naturally there are three of them. Instead being in the backside of the backside of the electrical panel the BN/BX cards are now in the front side. It was also interesting to that in 1965 it was a Century series locomotive that had first had an AC/DC transmission. In India in the late eigthies 11 locomotives in Tughlakabad was made into a AC/DC model but later reverted back to the same old DC/DC version mainly for maintanence reasons. It was again a trial at Lucknow on a WDM2 for an AC/DC transmission has led to the development of the WDM2C in the mid 90's (1994 to be precise).

The 2600 Hp prime mover ina WDM2 wastes 200 HP in running the compressor and exhauster unit. In fact it has been mentioned in GREAT BOOK OF TRAINS that it is only the addition of exhauster unit in the WDM2 for working vaccuum
braked trains is where it differed from the century series.

The initial WDM/2C units (referred to in the text above) featured a dreadful bald headed profile at the short hood. This series also marked the change of the driver's seating position from the right to the left. Here is head on view of the first bald headed WDM/2C fresh out of the DLW works.All the WDM/2Cs have an enhanced 3100 hp power pack. (Photo scanned from a DLW brochure, courtesy DLW veteran Mr. Venkat.)

The original braking system used in WDM2 had compressed air brake for the loco and vaccuum brake for the train and was termed the 28 LV-1 system while the current one is the 28-LAV1 system with the A to mean that it can operate air-braked trains also. The Kazipet shed and some other sheds in the south used to write a big A in the cab side meaning that it is fit air braked rake operations. When DLW started churning dual braked locos in the late 80´s mainly keeping in head the need for the new BOX N and BCN frieght trains coined the term WDM2A.

Again with the rise of the air-braked passenger services they put forward a loco termed WDM2B with dummied exhauster unit and is used to operate only air-braked trains. The first WDM2B that I experienced was at Kharagpur and it was numbered 16711 and had a slightly different radiator design with a more fuel efficient engine than the regular WDM2. 16711 went on to be a regular performer on the Bhubaneswar Rajdhani Express between Bhuabaneswar and Kharagpur.

The WDM2 controls have a very scientific layout in a sense that it cleary divides the pneumatic part and the electrical part. All those who think of the WDM2 cab as their second home knows about this fact very clearly. The air-braking controls are on the right with brake-valves and pressure gauges along with Sanding and MU2B valve and on the left are the electrical controls which are the throttle handle, reverser handle, selector handle, the loadmeter, ( the electrical speedometer on the long-hood facing stand), the headlight switch, the hotengine,lowlubeoil, crakcase failure and auillary generator failure, wheel sleep indication panel. Just above the selector lever is the Generator Field Switch (one of the major component) the master controller and the fuel-pump circuit breaker.

There was another type of braking system used on the WDM2s called 6SLAV -1
and I had seen such a system fitted in some locomotives of Vishakapatnam.
The SA-9 ( loco brake ) was pretty strange and rather odd looking in this
set up.

I will deal with the influence of WDM2 on IR in operations and technologies in the final part of my tribute to the great locomotive.