Recently I saw a replica of a Synchronome electric master clock on display
in a private museum. I noticed that part of the movement is a lever
controller for manual operation (usually in the lower left hand side of
the case, in pictures I have seen of other examples of this type of clock)
with three positions, marked "N," "R," and "A." What is the function of
this lever, and what do the letters n, r, and a stand for? (No jokes
about the National Rifle Assoc., please). Regards, Ian D.

Ian W. Douglas wrote:
Recently I saw a replica of a Synchronome electric master clock on display
in a private museum. I noticed that part of the movement is a lever
controller for manual operation (usually in the lower left hand side of
the case, in pictures I have seen of other examples of this type of clock)
with three positions, marked "N," "R," and "A." What is the function of
this lever, and what do the letters n, r, and a stand for? (No jokes
about the National Rifle Assoc., please). Regards, Ian D.

If memory serves, A and R stood for advance and retard -- used for
setting. N maybe stands for normal.

--
John Miller
email domain: n4vu.com; username: jsm(@)

John Miller wrote:
Ian W. Douglas wrote:

Recently I saw a replica of a Synchronome electric master clock on display
in a private museum. I noticed that part of the movement is a lever
controller for manual operation (usually in the lower left hand side of
the case, in pictures I have seen of other examples of this type of clock)
with three positions, marked "N," "R," and "A." What is the function of
this lever, and what do the letters n, r, and a stand for? (No jokes
about the National Rifle Assoc., please). Regards, Ian D.


If memory serves, A and R stood for advance and retard -- used for
setting. N maybe stands for normal.


I believe that is correct. In the event of an
interruption causing the Slaves (and Master) to
show the wrong time, they could be rapidly stepped
from the Master clock to reset them. The Master
clock would then be set in the (N)ormal running
position.

I remember sitting in classrooms fascinated by the
rapid clock motion on these occasions - and it
wasn't exactly quiet about it as I recall. Usually
the teacher would stop until it finished and he
had (more or less) our attentions again.

In article ,
WoofWoof wrote:

John Miller wrote:
Ian W. Douglas wrote:

Recently I saw a replica of a Synchronome electric master clock on display
in a private museum. I noticed that part of the movement is a lever
controller for manual operation (usually in the lower left hand side of
the case, in pictures I have seen of other examples of this type of clock)
with three positions, marked "N," "R," and "A." What is the function of
this lever, and what do the letters n, r, and a stand for? (No jokes
about the National Rifle Assoc., please). Regards, Ian D.


If memory serves, A and R stood for advance and retard -- used for
setting. N maybe stands for normal.


I believe that is correct. In the event of an
interruption causing the Slaves (and Master) to
show the wrong time, they could be rapidly stepped
from the Master clock to reset them. The Master
clock would then be set in the (N)ormal running
position.

I remember sitting in classrooms fascinated by the
rapid clock motion on these occasions - and it
wasn't exactly quiet about it as I recall. Usually
the teacher would stop until it finished and he
had (more or less) our attentions again.

I remember in elementary school once seeing the clocks being set as you
describe... remember being amazed. They were Simplex clocks IIRC.

The folks over in alt.horology get on the subject of old master clock
systems now and again...

Erik

Here's some information on that interesting clock.

http://www.awco.org/Clocks/Synchronome/synchronome.htm

Retard is accomplished by lifting the click (pallet) out of the count
wheel. How the advance works is not obvious to me.

http://www.awco.org/Clocks/Synchronome/mvtclose.jpg

There are 15 teeth in the count wheel, so I guess the slave clocks move
in 1/4 minute intervals. If the system is 5 sec slow, the setting
procedure would be to bump the slave clocks up by 1/4 minute, then move
the lever to the retard position for 10 seconds, then N.

Factory guarantee was 2 sec/week per info in the pdf file.

Revision wrote:
There are 15 teeth in the count wheel, so I guess the slave clocks move
in 1/4 minute intervals. If the system is 5 sec slow, the setting
procedure would be to bump the slave clocks up by 1/4 minute, then move
the lever to the retard position for 10 seconds, then N.

Factory guarantee was 2 sec/week per info in the pdf file.


they send a pulse every 30seconds, it uses a seconds pendulum and only
pulls the index wheel around on the second swing or every 2 seconds.

the index wheel has a finger attached that once per revolution pushes a
locking away allowing the gravity arm to fall, it's roller pushes
against the inclined plane fixed on the pendulum rod, this gives the
impulse to the pendulum, once the roller is almost to the bottom of the
inclined plane the gravity arm closes a contact which trips a solenoid
that flicks the gravity arm back up to the lock position and at the same
time any slave dials on the circuit will trip forward by 30seconds.

the advance-retard lever when set to retard simply disconnects the slave
dials from the circuit, so if you wanted to turn back the clocks for
daylight saving you set the lever on retard for an hour, the slave dials
will not advance until you set the lever back on N or neutral/normal.

there is generally an extra set of contacts attached to the pendulum rod
up high and hidden behind the slave dial(if one is fitted), these are
used for 1 second impulses or signals, when the lever is set to Advance
the slave dial circuit is now wired to the seconds contacts and all
slave dials attached will now jump forward in 30second increments every
second, this way all the slave dials can catch up to the correct time.

operation the A-N-R lever does not affect the running of the master clock.

the better set-up master clocks had a "synchroniser" added, it worked
similar to a chronograph reset lever, on a signal from a timebase like a
radio time signal, the synchroniser would reset the index wheel so the
slave dials would trip within a couple of seconds of the correct time.

BTW the setting of the slave dials, the time shown on the dials is
dependant on the position of the index wheel, if the index wheel is
25seconds out all the slave dials will trip 25seconds out and no amount
of fiddling with the A-N-R lever is going to fix that, you have to turn
the index wheel around so when the gravity arm drops it's on or close to
the 60second mark.