Talyvel: It turns out that there are two US patents that mostly
describe at least the early versions of the Taylor-Hobson Talyvel
electronic level.

3,081,552 "Suspension Devices" to R. E. Reason, issued 19 March 1963.

3,160,237 "Damping Device" to R. E. Reason et al, issued 8 December 1964.

The fact that the above two patents "partially" describe the Talyvel is
mentioned in US patent 3,902,810, so this may well be it.


The Wyler AG levels are based on capacitance. The relevant US patents
a

4,023,413 "Device for measuring Accelerations, Particularly
Accelerations Due to Gravity" to Stauber, issued 17 May 1977.

5,022,264 "Instrument for measuring Accelerations, Particularly
Gravitation Components for Goinometry", to Stauber, issued 11 June 1991.

Siegfried Stauber was the Chief Engineer of Wyler AG at the time.

http://www.wylerag.com/IMAGES_2008/history.pdf

The picture of Dora Wyler scraping a surface plate reminds me of the
grimy young child hidden behind the machines in in the northern brush
factory.


Both instruments sense tilt by means of a pendulum swinging on a
zero-friction pivot of some kind.

The Taylvel senses pendulum motion by means of variable reluctance and
thus inductance. As the pendulum moves, one air gap widens while the
other gap narrows. The two inductances are compared in an impedance
bridge, yielding null at level. The drive frequency is about 10 KHz.

The Wyler level senses pendulum motion by means of variable capacitance.
As the pendulum moves, one inter-plate gap widens while the other gap
narrows. The two capacitances are compared in an impedance bridge,
yielding null at level. The drive frequency is not stated, but is
probably near to 1 MHz.


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Joe Gwinn