Wow... I don't know if that looks like a great idea or a very dangerous one! I've seen hotwalkers, but never something like that! Interesting.
Sorry for the long delay, I had to go to a meeting.
It's definately very stout. I talked to him on the phone night before last to check on Truly and he said he's had a "shore-nuff" wild one in there since I was there. It was a very stout spotted saddle horse that had already busted down the gate of his round pen when he was trying to teach him to longe. He puts them in a regular work harness with a collar, britchin, trace chains, the whole 9 yards. The outside shaft is hinged and swings out so it's easy to get them in there. Then it's closed back and has a lynch pin to lock it in place. He sits on the little bench at the back. He said this horse took off like the devil was after him when he first started out, but settled down and worked very nicely after a very short period of time. He's supposed to show me how it works this evening when I go pick Truly and Ellie up. It was funny, he said the next thing he's adding is a seat belt. I can see why. If you get a horse going that fast in a 40ft circle, you could very easily get slung off.