https://www.answers.com/individual-sports/On_a_bicycle_Is_the_rear_hub_ratchet_mechanism_necessary
On a bicycle Is the rear hub ratchet mechanism necessary? - Answers
Not really, but it sure makes riding easier. There are hubs w/o the ratchet mechanism, and they're called fixies, or fixed wheels. Some like them for the more...
on a bicycleratchet mechanism
https://elifesciences.org/articles/15598v1
Two-way communication between SecY and SecA suggests a Brownian ratchet mechanism for protein...
two way communication
https://www.instructables.com/Ratchet-Knob-Unidirectional-Mechanism/
Ratchet Knob (Unidirectional Mechanism) : 12 Steps (with Pictures) - Instructables
Ratchet Knob (Unidirectional Mechanism): A ratchet is a mechanical device that allows motion in one direction but not the other. An example of this is the...
ratchet knob12 stepsunidirectionalmechanismpictures
https://elifesciences.org/articles/15598/peer-reviews
Peer review in Two-way communication between SecY and SecA suggests a Brownian ratchet mechanism...
Evidence is presented that supports a completely new, diffusion-driven mechanism for transporting proteins across membranes in bacteria.