Standard Electric Time with mercurial pendulum adjustment problem

PhilipG

New Member
Jul 1, 2020
2
0
1
63
Country
I recently acquired a 1927 Standard Electric Time master clock that was used at a railway station (so it doesn't have the tape mechanism). Originally it ran on 16 Volts, but the self winding works much better at 19 volts.

My current problem is that I'm unable to shorten the pendulum enough to have it run at the right speed. With the bottom nut screwed up all the way, it still runs around 13 seconds a day fast. I don't know what the history of this clock is so I don't even know what the previous owner did to it.

I have an optical measuring system to track the tick rate, and it seems pretty stable (even with the door open). It has varied by about 3 parts per million over the last hour.

IMG_20200719_161749.jpg IMG_20200719_162007.jpg
This is the graph of the tick period over the last 70 odd minutes.
tickperiod.png
The contacts are a bit chewed up, one of the platinum-iridium contacts appears to have dropped off entirely, but that was a long time ago as it has managed to dig a hole in the mating contact -- happily that is for the pulse drive circuit rather than the winding circuit.
IMG_20200719_162127.jpg

Also, I'm unable to adjust the winding pawl so that it is in the middle of a tooth. There just doesn't apper to be sufficient travel in either of the two adjustment points (which are screws that hold levers in position). I'd rather not increase the size of the holes in the brass before consulting someone who knows more than me.

IMG_20200719_162516.jpg

My current thought for the pendulum is just to put a small washer between the bottom adjustment nut and the base of the frame that holds the mercury cylinders. Does this seem crazy?

Thanks

Philip
 

PhilipG

New Member
Jul 1, 2020
2
0
1
63
Country
Actually I was confused -- it is running (currently) 200ppm slow (my code gives me the tick period, and this is a little bigger than 1 second, so it is running slow). But thank you for making me check my assumptions!
 

Forum statistics

Threads
166,931
Messages
1,454,656
Members
87,192
Latest member
justincasejustintime
Encyclopedia Pages
1,057
Total wiki contributions
2,914
Last edit
E. Howard & Co. by Clint Geller