Talk:Thompson coupling
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[edit] Sliding surfaces
Good point User:Van helsing - cardan joints don't have sliding surfaces, but CV's do - the balls slide against the inner race when the input and output shafts are at different angles. It is removing this source of friction that is claimed to be a benefit, and is one of the critical aspects of the invention. This source of friction has been the subject of significant research, particularly in the development of grease for CV's. I reverted back some material, but left out the sliding surfaces for cardan joints. I reverted back the aspects of axial and radial loads because these are in fact significant improvements over the traditional CV joint. CV joints cannot cope with significant axial loading with rotation.
Your point about sales hype is a good one, but the features of the joint are unambiguous, and are the reason the joint has been developed. To leave these aspects out would be perverse. GrahamP 10:09, 12 February 2007 (UTC)
- Thanks for your post. The sliding surface thing however makes me a bit curious: "the balls slide against the inner race when the input and output shafts are at different angles". I’m actually quite convinced that the balls in a Constant-velocity joint are supposed to roll in their grooves (like in a ball bearing). Apart from moving grease around, I don’t see a cause for (sliding) friction here (but always willing to learn of course). I agree to your axial and radial load statement; that is where the advantage lays when you need a constant velocity joint. --Van helsing 13:20, 13 February 2007 (UTC)
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- Thanks for the reply. In a standard roller bearing, the groove runs circumferentially, with the movement of the ball in the same direction as the groove, but in the CV joint, the grooves run axially, with the torque acting on the CV joint causing the balls to force on the sides of the grooves. The balls slide up and down the grooves only with differential angles between input and output shafts. This is where the friction comes into play. In theory (I think), if there was no differential angle, there would be (almost) no friction, but in that case, you wouldn't need to use a CV joint. GrahamP 21:53, 13 February 2007 (UTC)
- Still, that would make it a rolling friction, not a sliding one (bit like a axial loaded standard ball bearing). Anyway, wrong or right, the claims are sourced, therefore okay to state it like that. --Van helsing 22:12, 13 February 2007 (UTC)
- Thanks for the reply. In a standard roller bearing, the groove runs circumferentially, with the movement of the ball in the same direction as the groove, but in the CV joint, the grooves run axially, with the torque acting on the CV joint causing the balls to force on the sides of the grooves. The balls slide up and down the grooves only with differential angles between input and output shafts. This is where the friction comes into play. In theory (I think), if there was no differential angle, there would be (almost) no friction, but in that case, you wouldn't need to use a CV joint. GrahamP 21:53, 13 February 2007 (UTC)
