Re: Lubrication of gravity arm latch where it engages the gravity arm?

John Hubert

On the ‘beat plate’ on a Synchronome, there are (at least) two types:

  • The earlier type has Roman numerals II - I - 0 - I - II and represents degrees away from the rest point (i.e. vertical) based on approx 19 mm per degree.
  • The later type has conventional numerals 5 through 0 to 5 and represents ’total inclusive arc’ 

That is how I understand it anyway.

John Hubert

On 18 Apr 2019, at 10:39, John Howell <j@...> wrote:

Hello Neil,

Our two Synchronomes are for different tasks, yours for controlling the station's output, mine for recording it! See attached photo. And thank you for the pictures, yours is a very fine clock.

In the UK we have become a bit sloppy in the use of the term 'Power Station Synchronome'. My clock should be referred to as a 'Grid Monitoring (or Metering) clock' & is more common here.

Yes, the mercury switch runs the Printometer for a preset length of time every 1/2 Hour, these actions being controlled by the master clock.

Best regards,

John Ho.

On 17/04/2019 22:54, neil wrote:
Hi John H,
                 Thankyou for your photos. I have not seen that version before. I gues the mercury relay was the control output.
My clock is quite different. It has a synchronous movement which ran off the mains power from the power station, which of course would run fast or slow if the generator was running above or below the 50Hz mains freq. The other display ( labelled GMT) runs from the 1 second impulser at the RHS of the upper end of the pendulum.
 I assume the operator would compare time between the master clock (labelled ASEA) and the synchronous time and open or close the water supply to the generator as needed.  It also has that lovely little weight that can be placed onto the weight tray without opening the door, to adjust the master clock - presumably from listening to the time blips on the radio. 
 This clock was in a small power station called Lake Waikaremoana in the North island of New Zealand, and was 'rescued' about 30 years ago. It runs very nicely but neither of my 'nomes keep time even close to an IBM master that I have. 

Neil Jepsen. B.Sc. M.Sc(Hons).CPL.MASNZ.
Jepsen Acoustics & Electronics Ltd
22 Domain Street
Palmerston North.
New Zealand.
Ph +64 6 3577539  Mob 0274428094
Web site:
E.& O.E.
On 18/04/19 12:47 AM, John Howell wrote:


Attached are some pictures, the serial No is A315 & I have the Printometer to go with it.

I would dearly like to know how the setup worked, not the technical operaton but what it told the person who was in charge of it, & how the adjustable delay affected readings.

If you want some more specific photos at higher resolution let me know.


John H.

On 17/04/2019 12:11, neil wrote:

John..I'd love to see a photo of your power station nome, because I also have a power station 'nome.

On Wed, 17 Apr 2019, 10:34 PM John Howell <j@...> wrote:

Agreed, my 1960s Power Station Synchronome won't gather a tooth if the arc is less than ±2.5 and it normally runs between 3.5 & 4.

As a matter of interest my beat scale is 9.7 cm between the '5s', Surely Hope-Jones would not have allowed this?!

John H.

On 17/04/2019 10:36, stephen@... wrote:
Yes, Brian, I'd say you are right. The point is that if the clock is correctly set up and everything is in order, then it should run at +/-4 or so on the beat scale (mine reaches almost 4.5). If, after that, you then wish to reduce the amplitude (by lightening the gravity arm, shortening the impulse etc) then that is a different matter. Yes, it's true that the amplitude of most precision mechanical clocks would be a lot less.


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