T i m wrote:

On Wed, 13 Feb 2019 02:44:10 -0800 (PST), wrote:

snip

In fact I would suggest *most* of the damping was done by the concrete
and a bit more was supplied by the dampers, along with some alignment.

Yes there are certainly variants. The concrete makes a huge difference to
drum movement - a machine run without one is quite out of control.

As a neighbour found out recently when the concrete 'ring' round the
front broke up and (partially) fell out. ;-(

Technically the concrete doesn't damp it.

Anything that resists any oscillation can be considered a damper.

https://en.wikipedia.org/wiki/Tuned_mass_damper

Cheers, T i m

An interesting change of use. It is a loss of a word to describe
absorbing energy rather than changing resonant frequency though.

--

Roger Hayter