I'm not sure about other quick hitches, but the Attach-matic that we use, for silage wagons, has an additional pin, that they want you to install, for highway travel = it locks the "release pin/block" into place, so it can't be released going down the highway.

http://www.attachmatic.com/EN/details.php?IID=59

{I don't see a photo, for their larger version, using 1" pin}

We still use hitch pins, on gravity wagon, during harvest (quick hitches, only used for forage = close to home=no highway travel)

Note: Yes, I get out and rehook to every wagon, during harvest, but all wagons have extendable tongues, so it isn't a problem, PLUS you need to hook up your wiring plug, for your safety flashers anyways.

(Double HH pin.jpg)

Double HH pin.jpg (5KB - 161 downloads)