Revolving door hog traps.. how well do they work?

Yeah the ole swing gates work great . I tie a hook hanging down and set the door on it in the up postion and run some weed eater string threw a dog clip clipped on the top of the panel then run the string to the back threw another dog clip and tie it to the other side of the pen when the hogs come in they trip the door and if others are there around with them they just push their way in when they see the other hog eating . LOL had a 8 foot long trap here a couple weeks ago had 7 hogs in it stuffed in so tight I could not hardly get the door open to load them LOL. Each one was over 100 lbs and a couple 150 lbs