Modernization can greatly improve operational reliability by replacing mechanical relays and contacts with solid-state electronics.

Now there was a single last barrier - a crude but effective mechanical relay, holding apart two contacts.

The mechanical relays emitted an audible "clicking" sound when they engaged and disengaged.

Inherently smaller than a mechanical relay of similar specification (if desired may have the same "casing" form factor for interchangeability).

As he unloaded more poison, he could feel the mechanical relays reach for him.

George Stibitz (1937) invents the binary adder using mechanical relays.

Electrical and mechanical relays are out of the question.

The mechanical relays being replaced take up an entire room.

Those looked like mechanical relays of some sort, and they were made of solid mercury?

(There is no reason to believe that mechanical relays will make the best switches, but their performance is easy to calculate.)