Component record · Regulation
Suspension Spring
VerifiedA thin, flexible strip of spring steel from which the pendulum is hung, allowing it to swing freely while maintaining a fixed pivot axis.
What it does
Provides a near-frictionless, precisely located pivot for the pendulum's swing, replacing a pivoted bearing that would introduce friction and wear.
How it works
The pendulum hangs from the flexible spring rather than a pivoted arbor; as the pendulum swings, the spring flexes elastically about a virtual pivot point rather than rotating a shaft in bearings.
Because there are no rotating surfaces in sliding or rolling contact, friction losses at the suspension point are minimal, which was an important advance for precision timekeeping over cruder pivoted suspensions.
The crutch engages the pendulum rod just below the suspension spring to receive impulse from the escapement, imparting just enough energy each swing to sustain the pendulum's motion against air resistance and residual friction.
Evolution
Refinement of suspension-spring quality and consistency was a significant factor in the development of precision regulator and observatory clocks in the 18th and 19th centuries.
Known variations
- Simple flat suspension spring
- Special assemblies incorporating adjustable spring length or thickness in some precision regulators
Identification for collectors
- A thin flexible strip visible where the pendulum attaches to the movement, distinct from a rigid pivoted joint
Common failure modes
- Fatigue and eventual breakage from continuous flexing over long service life
- Kinking or damage from mishandling during case transport
Photographs
Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.
Sources & references
- Britten, F. J., Old Clocks and Watches and Their Makers
Where sources disagree, the disagreement is stated rather than resolved silently.