Shimano's "Servo-Panta Mechanism" referred to their upper pivot spring, which enabled the guide pulley to maintain a constant distance from the pulley teeth. Dura-Ace/""EX, 600/""EX and Deore were Servo-Panta; the AX-series were not.
By the mid-'80s Servo-Panta had morphed to "Double Servo-Panta Mechanism," which was the upper pivot spring combined with SunTour's slant-parallelogram design. Double Servo-Panta combined with Shimano's Centeron upper pulley (and Shimano effectively policing compatible frame dimensions and chain/cable/casing spec) is what made indexing reliable and desireable amongst consumers. A quantum shift (tee-hee) occured, and we spin off-topic.
Anyhow, google "servo-panta mechanism" and you'll now get a whopping 3 hits.
Cheers,
Paul Brodek Hillsdale, NJ
On Wed, 10 Mar 2004 15:58:16 -0500, "Stephen Barner" <steve@sburl.com>
wrote:
>That would be servo-pantograph. I can't see that it actually featured
>either. Just marketing disguised as bad translation.
>
>Steve Barner, Bolton, Vermont
>
>----- Original Message ----- > Date: Wed, 10 Mar 2004 11:52:50 -0800
>> From: "brian blum" <bbspokes@lycos.com>
>> To: classicrendezvous@bikelist.org
>> Subject: [CR]servo patho versus slant parallogram
>> Reply-To: bbspokes@lycos.com
>>
>> Did I get that right? Weren't the Sun Tour's called Slant Parallogram and
>Shimano's called the Servo Patho? Google can't find Servo Patho but I think
>that was Shimano's terminology.
>Brian Blum in Oakland,CA
Paul C. Brodek
Hillsdale, N.J. U.S.A.
E-mail: pcb@skyweb.net