The left hand can pull on either arm / hand too. "There is no fixed technique" - Chen Pan Ling. They don't have to be, and I've seen and recognise techniques where they are not. Though I expect at least in brush knee you will often place your leading leg strategically outside of your opponents leading leg for the above technique. But I also accept techniques where the legs are involved directly in some way shape or form. In this case the reap for repulse monkey.. In brush knee (Yang style) I recognise a trip with the instep in the transition. You turn to 'hold the ball' posture... and you open the toes out to reveal the instep as you turn (to 'hold the ball') towards your leading leg. Do that movement from an over and under clinch position. It maps directly to throwing someone over your instep for a trip. I mean literally a direct map! Why not use it like that ? We can ask that regardless of traditional uses or not. If we discover something that possibly wasn't thought of by someone or other in the past. And it is an if.. But if so, why ignore it. You seem to be saying ignore the potential leg uses, because tradition.. Sorry, but I don't agree at all. If they prefer to stand on 2 legs so much, why then, literally stand on one leg in the transition posture of repulse monkey? There is already a documented tradition for hidden kicks for example, which are leg moves effectively. As well as the well documented "every step is a kick, every kick is a step". I think this is not all that different at all and extending it to encompass trips and sweeps is indeed pretty logical. So for example the outside crescent kick can double up, quite easily, as a sweep. Others mileage may vary of course (standard).