On Tue, 15 Dec 2009 21:58:21 -0000, "newshound"
wrote:



"Grumpy" wrote in message


The best constant force spring is a air cylinder with a pressure regulator
suppling the air.
Constant pressure and no fatigue failures.

Apart from friction in the seals. Even on an oil hydraulics system. If you'd
ever tried it you'd know.

It's best to be sure of oneself when playing the know-it-all...

http://www.airpot.com/html/apply_precise.html

Frictionless and low-friction cylinders are also available from SMC.

--
Ned Simmons