tightlock

English

English Wikipedia has an article on:

tightlock coupling

Wikipedia

Etymology

From tight +‎ lock.

Noun

tightlock (plural tightlocks)

1. (often attributive) A form of Janney coupler, typically used on North American mainline passenger rail cars, having mechanical features that reduce slack in normal operation and prevent telescoping in derailments, yet remain compatible with other Janney types.