At 08:01 PM 12/3/2007, Stephen Overmyer wrote...
>The Thompson Coupling is a frictionless replacement for Uni and CV
>joints that requires no maintenance although I am sure the initial
>cost
>will be higher.

The BS-ometer immediately goes into high alert when I see claims like
"The Thompson Coupling is as essential to our mechanised age as the
screw, the crank, the lever and piston...one of the most important
inventions of our time" side-by-side with an

Then, there are claims that "Does not require special lubrication
Does not require a dust boot," but they also say that the first
commercial units "are encased in a pressurised rubber bladder to help
cope with the abrasive operational conditions."

It's pretty clear what the hype is all about, they're quite upfront
about it, with great hubris: "We believe that an investment in Thompson
Couplings Limited at this time is a so called ground floor opportunity
the like of which only occurs in relation to great inventions such as
the telephone, the radio, the pneumatic tyre, the Thompson Coupling,
etc.,"

A look at the design shows that it has many more machined surfaces and
parts (= more expensive) than a common Rzeppa CV joint, which can last
indefinitely in automotive use. (i.e. >100K miles with no, or very
minimal, maintenance, more with occasional cleaning/greasing). Take a
look at the parts in a "Thompson joint:"
http://cvcoupling.com/images/stories/torque1.jpg (note that the picture
doesn't show any of the multiple roller bearings needed!) Contrast to
the 3 major parts and 6 balls in a Rzeppa joint.

BTW, sealed roller bearings are NOT "frictionless."

Pass.