Friday, January 30, 2026

do diesel hydraulic train engines exist?

IN Knight and Day(2010) the are talkung about a diesel Hydraulic Train Locomotive engine. I didn't know something like that even existed. So, I checked and something like this does exist when extra torque for mountains is necessary and useful. Interesting.

I only knew it would be theoretically possible to build and engineer something like this after working with Tractors landscaping Contractor in San Diego county when I was in my late 20s and early 30s. 

Because Tractors lifting capabilities like on Backhoes and loaders are Diesel Hydraulic Too! 

 begin quote:

Diesel hydraulics: Diesels that didn't - Trains
Yes, diesel-hydraulic train engines exist, primarily utilized for locomotives and multiple-unit trains where lighter weight, higher acceleration, or specific torque characteristics are required, such as on German and European mountain railways. They operate by connecting a diesel engine to a hydraulic transmission (torque converter) rather than an electric generator. 
Key Characteristics and Usage:
  • Transmission Mechanism: They use hydraulic fluid in a converter to transmit engine power to the wheels.
  • Advantages: Lighter weight compared to diesel-electric, excellent starting tractive effort, no wheel-slip under load, and high acceleration, making them ideal for hilly, mountainous terrain.
  • Regional Popularity: Germany was a leader in this technology (e.g., V200 class), developing them post-WWII, and they are still used in parts of Europe, India, and Japan.
  • Applications: Primarily used for passenger railcars (DMUs) and light switcher engines, rather than heavy freight hauling, which is dominated by diesel-electric.
  • North American Context: While mostly used in Europe, some diesel-hydraulic locomotives, such as the German-built Krauss-Maffei models, were used in North America in the 1960s, though they were not widely adopted. 

While they offer advantages, their, often higher maintenance costs led to the dominance of diesel-electric technology, according to the YouTube video from 2018 and the Reddit post. 
  • How Diesel Hydraulic locomotives work
    Oct 1, 2018 — direction a diesel hydraulic locomotive is lighter than a corresponding diesel electric locomotive. because it does not have to ca...
    YouTube·The Train Story
4:20
3m

Show all

  • A Query About 'Diesel-Hydraulic' Locomotives : r/trains - Reddit
    Oct 5, 2025 — OP you are completely correct. The vast majority of "diesel hydraulic" locomotives and DMUs are diesel engines coupled to final dr...
    Reddit
  • How EVERY TYPE of Diesel Locomotive Works! (Part 3)
    Apr 28, 2023 — but they still ain't as good as diesel electric. today they're mostly used in Germany and Finland though some neighboring countrie...
    YouTube·Southern Plains Railfan
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