What Happened to B-Units_ The Truth Behind the Diesel Booster

Описание: In the 1930s, American locomotives underwent a massive transformation. As the age of steam engines faded, a daring new concept promised to revolutionize railroading: the B-unit. This video explores the fascinating history of these "ghost" engines—cabless boosters designed to snap onto a lead locomotive and double the horsepower without requiring an extra crew member.





We dive deep into the engineering behind the A and B unit systems. While the A unit housed the engineer and controls, the B unit was stripped of creature comforts—no windows, no seats, and no cab—yet it contained the exact same prime mover and traction motors as the lead engine. You will learn about the crucial role of the Multiple Unit (MU) cable, the "secret" that allowed a single engineer to control an entire lash-up of American locomotives as one coordinated machine.





The video also covers the Golden Age of these diesel boosters, highlighting the legendary Electro-Motive Corporation (EMD) FT model. We discuss how these units proved that modular diesel sets could outperform steam on heavy freight runs across the United States.


However, the rise of the B-unit wasn't without controversy. We analyze the tension between railroad corporations and unions, specifically the Brotherhood of Locomotive Firemen and Enginemen, who saw these empty, automated boosters as a threat to their jobs.

Finally, we track the decline of the B-unit. From oddities like the Rock Island AB6 and "Crandall Cabs" to the rise of versatile road switchers like the GP and SD series, we explain why the industry eventually moved away from cabless boosters. We conclude with a look at the Santa Fe GP60B—the B-unit's last "moment in the spotlight"—and the modern high-horsepower era that made them obsolete.





Join us for this deep dive into the engineering, politics, and history of American locomotives!

⏱️ Chapters

00:00 - The End of Steam and the Diesel Idea



00:33 - A-Units vs. B-Units: The Engineering Differences


01:34 - The Secret of the MU Cable


02:17 - The EMD FT: Challenging Steam Power


04:17 - Union Controversy: "Diesel Locomotives Threaten Jobs"



05:49 - Operational Advantages of A-B-A Sets


06:08 - Strange Hybrids: The Rock Island AB6


07:01 - The Rise of Road Switchers (GP & SD Series)


08:09 - Amtrak’s "Head-End Power" Conversions


08:39 - The "Crandall Cab" Experiments


09:03 - The Last Stand: Santa Fe GP60B



09:58 - Why Modern American Locomotives Stand Alone