Ein "Mitnehmer" ist in der Technik ein allgemein gebräuchlicher Begriff.

pusher dog | der Mitnehmer Pl.: die Mitnehmer
driving dog [AUTOM.] | der Mitnehmer Pl.: die Mitnehmer - Ventiltrieb
dog [TECH.] | der Mitnehmer Pl.: die Mitnehmer
https://dict.leo.org/englisch-deutsch/Mitnehmer

Erst aber mal zu den Kinnriemen am Helm:

Helme werden durch Kinnriemen am Kopf fixiert; heute sind dies Ratschenverschlüsse.
https://de.wikipedia.org/wiki/D-Ring

There are five basic types of helmets intended for motorcycling, and others not intended for motorcycling but which are used by some riders. All of these types of helmets are secured by a chin strap, and their protective benefits are greatly reduced, if not eliminated, if the chin strap is not securely fastened so as to maintain a snug fit.
https://en.wikipedia.org/wiki/Motorcycle_helmet

Quick Release Buckle
Quick Release Buckle fastening benefits from easy and fast closing and opening. This feature you appreciate everytime you take your helmet off frequently, for example when shopping or on the trip. A quick release buckle gives you the flexibility to remove the helmet quickly if needed.
• Fastening
The metal buckle attaches to a high quality safety strap. On the other strap is a ribbed plastic tab. Insert the ribbed plastic tab into the metal buckle.
https://www.aspshop.eu/helmet-fastening#

Modern integral helmet with retractable sun visor, suitable for prescription glasses, excellent balance of quality and price, KPA composite shell, scratch and fog-resistant treated visor, Dynamic Flow-through Ventilation, fully removable and washable interior, nose deflector, removable chin spoiler, micro buckle closure, weighs 1550g
https://www.aspshop.eu/ls2-ff808-stream-ii-angry-monkey-m-bl...

A special locking mechanism developed by YKK is used to prevent loosening. We thought that if the special locking mechanism could be applied to the buckle of this bicycle helmet, the problem of the chinstrap loosening after prolonged use could be solved.
[image]
The upper buckle is the conventional product. The lower buckle is the newly developed "anti-slip buckle (Item Code: IB16RK). The marked area is the point of the new anti-loosening mechanism.
https://ykkdigitalshowroom.com/en/article/510/

4 point industrial rated chinstrap with quick release buckle ensures the helmet is secure during side impacts, but will break free if loaded across the neck
https://www.spanset.com/de-en/products/high-performance-helm...

Despite the metal version being the least common, it is the stronger of the two. This is because it is less likely to break than the plastic micrometric closure. This type of closure is also called a quick release buckle.
https://www.chromeburner.com/blog/dubble-d-or-micrometric-cl...

Comfortable padded chin strap with quick-release micro-metric ratchet closure
https://www.chromeburner.com/bell-broozer-duplet-solid-gloss...

This practical accompaniment fits all helmets with a ratchet closure (Micro-Metric), Nexus clip: The carry strap either connects with the existing ratchet closure or simply attaches to the close helmet clip.
https://wunderlich-adventure.de/en/wunderlich-helmet-carry-s...

Safer and Easier Alternative to Dogs and Ratchet Dogs.
https://sctegparts.com.au/CA4873-RATCHET-WEB-DOG-8mm-10mm-50...

A demountable handle includes a yoke and a ratchet dog insertable into a selected of the notches.
https://patents.google.com/patent/US3689029