Date:         Mon, 3 Dec 2007 23:31:09 -0500
Reply-To:     Kim Brennan <kimbrennan@MAC.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Kim Brennan <kimbrennan@MAC.COM>
Subject:      Re: The Thompson Coupling
In-Reply-To:  <20071204034825.44D5F1165C7@hamburg.alientech.net>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

It would appear to have some potential, but...

It appears to be a U joint inside of a U joint. I suspect that is why
it has less vibration (in the helicopter load variation, you could
see the load moving slightly)

Innovative certainly. Revolutionary? Not quite so sure about that. I
think of this in the same line as the evolution from ammonia style
refrigerators to compressor style. The compressor style is more
complicated, but has certain advantages.


On Dec 3, 2007, at 10:47 PM, Mike S wrote:

> 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.