On the Arrow Q-Catch headgate, you have to manually apply a small amount of pressure down on the gate handle to "close it". There is no "gravity" assisting this operation, as it is purely a horizontal gate movement. As soon as you stop putting pressure on the handle to go on to your other tasks, it stays/locks where you've set it by way of a spring activated cam latch. Easy... but............. the headgate WON'T take up any more slack by itself beyond that, like if you catch an animal at their shoulders, and then they back up. If their neck at the shoulders is wide, compared to their head, they can "slip" backward out of the headcatch. You can take up that slack manually, if you stay there and keep pushing down on the lever (fairly easy to do from a physical exertion standpoint), but that means that you're not as able to move on to your next task.
The Priefert 91 DOES function "horizontally" too, but it does this at the same time as the doors are "lifted" some, which gives it some "gravity assist" in closing it, and it is THIS difference in design function, along with a spring if you have it set in automatic, that it uses to operate its "automatic" functionality. To close the Priefert and catch the animal, you basically just "LET GO/take pressure off of" the lever, or STOP holding the gate open, rather than "pushing it shut" (less man effort). The two headgates operate similarly then in that they both move the door "primarily horizontally", but the Priefert, because of this difference in design, WILL take up the slack in this situation automatically (avoiding the potential for an animal to"slip" out backward). As the animal backs up and the neck narrows, the headgate will automatically close and remain "fit to the animal", up to the width of the narrowing neck (without uncomfortably "squeezing" the neck... it just takes up the given slack) as much as the animal gives it. There's no need/incentive then to actually "squeeze" the headgate shut "uncomfortably tight", which means the animals are more comfortable and quiet. It'll do this every time it "gives" some, the entire time the animal is in the headgate, until you release it. They're similar in principle as to how they lock (a camlock, spring assisted on the Q-Catch, gravity on the Priefert)... with primarily a straight in, straight out door function on each side.... but with a difference in how they function in these respects. The Q-Catch does not have an automatic self catch function, from what I've seen.
