Re: Master Clock contact spark quenching

Bob Holmstrom

On a visit to Sydney Australia in 2007, I was privileged to visit the building that houses Father O’Leary’s Clock (thought by some people to be a preaccessor to the Shortt Synchronome system).  I believe one of the members of this list was with me on the visit.

Anyway - Father O’Leary used a wiping contact version of a Hipp toggle switch - his prototype version was still attached to a laboratory wall.  As you can see in the photo below, the part of the switch that moves up and down is attached to a bracket on the wall and the ’notch’ and moving contact are attached to the pendulum rod.  The contact is wiped each time the ‘dangly bit’ catches in the moving notch.

O’Leary’s clock is shown in the two images below:


The more refined version of his Hipp switch is shown below:

More information on the clock is available in:

Horological Journal December  2004 and January 2005   and the NAWCC Bulletin February 1996 (A second clock by O’Leary is in the Smithsonian)

Bob Holmstrom
Horological Science Newsletter

On Jan 10, 2021, at 5:29 AMJanuary10, Simon Taylor <smktaylor1@...> wrote:

The contacts in the PO 36 were designed to 'wipe'. That is, that they continued to travel after contacting which led one to wipe over the other thus removing any oxide build up. I am not sure of the clock specifications, but for GPO 3000 relays, the contacts after meeting would then continue until a certain pre defined lift had carried the contacted spring clear of its buffer block (which it rested on) by a certain distance. this led to the contacts rubbing each other and so removing oxide build up.
Simon GPO Clocks

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