https://peertube.dngr.us/videos/watch/5a667c3d-699b-4623-ade6-527e55f1d455 Join this channel to get access to perks: https://www.youtube.com/channel/UCddem5RlB3bQe99wyY49g0g/join Want to learn more about Periscope Film and get access to exclusive swag? Join us on Patreon. Visit https://www.patreon.com/PeriscopeFilm Visit our website www.PeriscopeFilm.com Part One: https://youtu.be/JGKl3R2bMMw This film, "Telephone Relays U and Y Type (Part 2)" (1951) is a detailed technical explanation about the design, adjustment, and maintenance of relays used in the Bell System. It covers various aspects such as: • The durability and reliability of relays. • Differences between U and Y type relays. • Proper adjustment techniques to ensure optimal performance. • Common issues like dust, lint, and contact erosion, and how to address them. • The impact of magnetic interference from adjacent relays. • The importance of following specific procedures to avoid relay troubles. Essentially, it's a guide for engineers and technicians on how to maintain and adjust relays to ensure they function correctly and efficiently. • 0:36-0:50: Bell Laboratories (1:00). A technician provides an overview of the Bell System relays, highlighting their design, durability, and reliability. • 0:53-1:03: Introduction to U and Y type relays and their advantages over flat type relays. • 1:07-1:29: High speed photography is used for an examination of a properly adjusted U relay using high-speed photography to observe armature bounce and spring vibration. • 2:04-2:27: Explanation of improvements in armature design and spring proportioning to meet newer switching system requirements. • 2:44-3:53: Description of the Y type relay, its slow release characteristics, and the differences in magnetic circuits compared to the U type relay. • 4:03-4:19: Use of copper or aluminum sleeves to adjust the release time of relays. • 4:30-5:18: Comparison of fast release U relays and slow release Y relays using high-speed shots. • 5:20-5:53: Importance of following Bell System practices for proper relay adjustment to ensure good performance. • 6:02-7:23: Common relay troubles such as dust and lint on relay springs, and the importance of proper clearance and stud gap to prevent contact chatter. • 7:44-8:14: Explanation of armature back tension and the use of a gram gauge for proper adjustment. • 8:17-9:40: Importance of contact make (follow) and the effects of improper adjustment on relay performance. • 9:42-11:04: Discussion on contact erosion, its causes, and maintenance procedures to address it. • 11:21-12:17: Use of contact protection networks to reduce contact erosion and troubles. • 12:26-13:01: Importance of proper relay adjustment and the role of Bell Laboratories engineers in improving relay performance. • 13:05-14:23: Effects of magnetic interference from adjacent relays on relay performance and the importance of considering this during adjustments. • 14:31-15:01: Summary of the importance of following Bell System practices to avoid relay troubles and ensure proper adjustment. Motion picture films don't last forever; many have already been lost or destroyed. For almost two decades, we've worked to collect, scan and preserve the world as it was captured on 35mm, 16mm and 8mm movies -- including home movies, industrial films, and other non-fiction. If you have endangered films you'd like to have scanned, or wish to donate celluloid to Periscope Film so that we can share them with the world, we'd love to hear from you. Contact us via the weblink below. This film is part of the Periscope Film LLC archive, one of the largest historic military, transportation, and aviation stock footage collections in the USA. Entirely film backed, this material is available for licensing in 24p HD, 2k and 4k. For more information visit http://www.PeriscopeFilm.com Source: https://www.youtube.com/watch?v=aolJ7-B_cOw Mirrored from Periscope Film (https://www.youtube.com/@PeriscopeFilm) Sat, 13 Jun 2026 15:15:42 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://peertube.dngr.us https://peertube.dngr.us/lazy-static/avatars/41a6fee9-7f57-42d0-a5fc-5db4f1af2e31.png https://peertube.dngr.us/videos/watch/5a667c3d-699b-4623-ade6-527e55f1d455 All rights reserved, unless otherwise specified in the terms specified at https://peertube.dngr.us/about and potential licenses granted by each content's rightholder.