just started out

Posted: Sun Feb 05, 2012 10:23 am     Post subject: just started out

Hi,

just got interested in clock repairs and I have a replica chiming wall clock which wont work.

I have traced the problem to the main spring, as the clock will run if I drive the main cog after the main spring.

The problem is, I can't see anything wrong with the main spring. It winds. As far as I can see there is no damage. I cant understand how the cog is driven when there is a rachet stop preventing the mainspring cog from turning back.

Any help would be appreciated in understanding how this works.

regards Chrissib

Posted: Sun Feb 05, 2012 11:26 pm     Post subject:

this might explain it better.
http://electronics.howstuffworks.com/gadgets/clocks-watches/clock.htm

Posted: Sat Feb 11, 2012 10:47 am     Post subject:

very useful link thanks, but it still doesn't answer my question.

I know the power to the mechanism comes from the mainspring and when wound, the energy from the mainspring drives the cogs. but there is a black rachet stop which prevents the mainspring cog from unwinding when turning the key to wind up the clock. So if this rachet stop is preventing the spring from unwinding, how can the mainspring unwind and power the cogs.

I have already proved the clock will run when I power the mainspring manually. Think I am missing something.

Posted: Sat Feb 11, 2012 2:34 pm     Post subject:

The mainspring unwinds as the clock runs!

If the first part of your message is true then the mainspring must be broken. Can you wind it up all the way until you cant turn the key any more?

-Pete

Posted: Sat Feb 11, 2012 5:24 pm     Post subject:

I dont think the spring is broken. I have to displace the rachet stop to unwind the spring, and I have checked the coils when completely unwound. The spring does wind up completely, and will stop the key when tight.

What I dont understand is if the rachet stop prevents the mainspring cog from unwinding, how does the spring unwind under normal operation?

Posted: Sun Feb 12, 2012 12:05 am     Post subject:

the pendulum, and the escapement mechanism.

Posted: Sun Feb 12, 2012 12:52 am     Post subject:


Here is my try at an explanation, I would guess (as you didn't post pictures), that your clock is configuration number 2.

How a clock/coil spring works is, the spring has 2 ends, the outside tail end, and a center end. In order to get the spring to do work, you wind the spring storing energy, and anchor one end of the spring, the other end of the spring will move releasing energy to power the clock (or whatever).

There are 2 basic configurations:

1) The tail end of the spring is anchored to the frame of the clock, and the center of the spring is attached to an axel with a gear which drives the clock works. If the center axel is also the winding arbor, then the winding ratchet will likely be either on or in a gear on the axel.

2) The center of the spring is attached to an axel which is anchored to the frame of the clock, and the tail end is attached to a gear that spins freely on the axel. The tail end can either be attached to a post on the gear, or a barrel (tin can) is attached to the gear with the coil spring inside it and the tail end of the spring is attached to the barrel. If the center axel is also the winding arbor, then the winding ratchet will likely be on the frame of the clock (anchoring the spring when under tension).

Posted: Sun Feb 12, 2012 10:39 am     Post subject:

hi, thanks for your reply. Not sure I fully understad it yet. It would help if I could post a couple of pictures, but cant see an option for that.

Are you saying the ratchet/winding cog is stopped, but the drive cog can move independently, so although the rachet is prevented from springing back when being wound, the energy from the spring is allowed to move the cog?

Posted: Mon Feb 13, 2012 10:39 am     Post subject:


Yes, in configuration 2, the drive gear turns on the axel, and is not attached to it.

Posted: Thu Feb 23, 2012 8:07 pm     Post subject:

ok I am not very good at this, and I am trying to think logically. I think I have been on the wrong track since the start.

Bear with me...

As the mainspring is not broken, I have been assuming there is another problem with the power driving the clock. But if I look at the cog with the 'tick and tock' pendulum cog, (I think you call this the escapement cog), this IS being driven. If I operate the escapement cog, and manually cause a tick and a tock, the driven cog moves and continues to move. I dont think this would happen if there was no energy in the mainspring. Therefore I think the only problem I have, is the main pendulum runs down and the clock stops.

So my only question now is... what keeps this going when gravity pulls the pendulum to a stop?

Posted: Sat Feb 25, 2012 4:31 am     Post subject:

I would start from the beginning, are any of the holes in the plates where the gear shafts pass thru elongated? Are the holes dirty? Has it been oiled lately? Is the clock level, and in beat?

All these will stop a clock from working properly, it sounds like the mainspring is good.