Posted by Rick Denney on June 07, 2002 at 12:54:52:
In Reply to: What are they? posted by Clock Springs on June 07, 2002 at 12:30:51:
Modern rotary tubas use wire to make external springs. The wire wraps around the linkage shaft under stress and hooks over the linkage itself to return the valve.
Old clocks use flat steel tape instead of wire. This tape is wound around the shaft under stress and enclosed inside a brass barrel. In old tubas, the barrel is hooked to the linkage (and the outside end of the coil), and the center of the tape coil is hooked to the shaft.
If you see short round barrels where the linkage meets the linkage shaft, it has clock springs. If you see a wire spring wrapped around the shaft, it is the newer style.
Both work find in practice. The wire method is much cheaper to manufacture and install, and a lot easier to maintain and replace if it breaks--hence its use in current instruments. The only reason clock-spring linkages tend to be broken more often is because they are older.
Rick "who has lots of old clocks" Denney