YDM-4 Diesel Locomotive Internals

by Apurva Bahadur

---

Disclaimer: The information presented here is neither complete nor accurate. Complete details on the topics here are available only from Indian Railways and other official organizations. The material here is not a substitute for the official documentation or official training procedures, which are provided to duly authorized personnel. Do not use the information here to design, build, operate, repair, or maintain any equipment.

There are some interesting points to note about the YDM-4 in the photograph below.

See the photo gallery for other photos of this YDM-4 and others.

• The yellow stain near the radiator tank filler cap on the roof - this is from the coolant that contains yellow chromate additives for preventing corrosion.
• Offset exhaust of the YDM-4.
• Two of the six cylinders of the prime mover.
• The radiator fan that is still turning.
• Two cylinders of the four-cylinder expressor seen through the doors on the right.
• The doors contain the primary air filter elements for the prime mover's air requirement.
• The main oil bath maze filter is the large rectangular item on the top of the expressor.
• DC motor and pump for lifting fuel from the tank - this is the greenish - blue cylindrical item on the loco frame - which has to run whenever the loco is live.
• The curved item above the pump is the guard for the V-belts that drive the rear truck traction motor (RTTM) blower - the FTTM blower is driven off the bull gear on the free end of the traction dynamo/alternator.
• Finally, note the lovely angled roof line of the YDM-4 loco!

YDM-4 locomotive specifications and notes