willie wrote:amor wrote:what does this even mean Helical gears created by yi...
it's a level of integration which is necessary to power the drilling or boring requirements of Tai Chi
I wanted to let Willie respond to your question before saying anything. Here's what I was taught.
A basic principle of Taijiquan is whole-body motion, often stated as "When one part moves, all parts move". (In Chen style, some say, "When the dan tian moves all parts move".) To illustrate that principle, people have compared the use of the body in Taijiquan to mechanical devices that demonstrate similar behaviour. One such device is a gear train.
In a gear train, there is one gear that drives the other gears. When the driving gear turns, all of the gears in the gear train must turn: it isn't possible that any gear does not move. There is [little] "slack" between gears as all of the gears in the train are engaged. Given that it is metaphorical, it doesn't really matter what type of gears are being used, spur, helical, rack and pinion ... So, the idea is that the parts of the body move, one "rubbing" on the other, with [little] slack between parts, driven by one part. There are other subtleties, such as different size gears (motions), different speeds of rotation and different directions of rotation, but that's the central idea.
https://www.youtube.com/watch?v=D_i3PJIYtuYA mechanical device that behaves similarly is the "race" of balls in a ball bearing, where one ball in contact with the next rubs against and turns so that when one ball in the race turns, all of the balls turn. Feng Zhiqiang, for example, assembled his "18 ball" silk reeling set of exercises using that metaphor. (The 18 balls are the primary joints of the body, as he counted them.)
https://www.youtube.com/watch?v=1DDfdZFJ-7sThe concept is simple enough; achieving it is less so. In Chen style, silk reeling is, if well taught, the explicit method for doing so: one part rotating (twisting) causes the next to rotate.