Low and slow

I mentioned the care needed in disassembly. Here's another example.

In our last episode, as I removed various parts of the dog clock movement, I discovered a very unusual spring. Continuing our movement disassembly I spied another.

Pictured below are a couple of lifting levers for the striking mechanism. Under the shorter one is a wire, seen here protruding just above my thumb.

It appears to be another example of the use of a wire spring in a way I've not seen before.

It threads from a tiny hole on the top of the lifting lever, around its arbor on the right, then across the bottom of the lever and the front plate, then down through a tiny hole in the plate and is bent on the other side to hold it in place. 

Wires are commonly used as springs in clocks but less commonly in French clocks and I've never seen one like this.

The function is to serve as a spring, pushing the striking lever back in place after a strike of the movement. Striking referring to striking the hour: 2 strikes (of a bell or gong) for 2 o'clock, 3 chimes for 3 o'clock, etc.

With the lever removed:

The school / company S.C.A.P.H. definitely had some techniques I've not seen before. But overall this is one really well built movement.

One more example and now I'm going to go back to the beginning of a sort.

I mentioned striking. This clock, like many French clocks, uses a bell to sound the strike. They produce a very pretty tone.

Here is a photo of the movement in the case with the bell ready to ring.

Sitting just a fraction of an inch above the edge of the bell is the round hammer. When the clock strikes, the hammer is lifted by the various wheels, springs and levers in the movement and it falls on the bell to strike. The hammer, when lifted by the movement, needs to be pressed down to ensure it strikes correctly and doesn't accidentally stay in the lifted position instead of falling on the bell to strike.

It needs a spring.

Here's a shot of the round hammer (bell removed). It's attached to a thick, bent wire rod that is pinned to an arbor on the lower right.

Here's a view of that arbor from the interior of the movement. In the photo below you can see protrude on the left with a pointed, pyramid-shaped end. That end is what the hammer rod is pinned to in the photo above.

The arbor extends into the movement from the rear plate (left) to the back plate. When the clock strikes that arbor turns and the hammer moves up and the drops down. 

Except it really is pushed by a spring. Can you see it?

It's there in the photo above. Look at the center green arrow. See the thick, tapering wire that runs in front of the arbor? It protrudes from the front plate (right) and ends pointing towards the back plate. 

Look at the arbor again. Just to the left of the middle green arrow. The arbor has a rod protruding out. 

Here's a clearer view.

When the arbor turns the rod turns downward pressing against the spring wire and creating tension. At the movement rotates the hammer to strike that spring pushes the rod upwards, in turn pushing the arbor to spin in a direction that would bring the hammer rod downwards.

Here's the spring removed from the plate and held in the fingers of your local horologist.

I've seen springs like this used in cuckoo clocks and there's a couple in the DUFA box clock too. There it is in the shot below where you can clearly see the springs running along the arbors and pressing on rods on the left. In this case the rods are hook-shaped to ensure the spring doesn't slip.

These types of springs are typically tapered so you can push them into the plate and they friction fit. That said the springs are easily lost (almost) during repairs if one is not circumspect in one's clock disassembly management (ahem).

If you look again at the photo above of the spring in my fingers you will see that the team at S.C.A.P.H. made the extra effort to create a threaded end to the wire. Making insertion and removal easy.

Impressive.

I do love my DUFA box clock and its Largo gong but when you look at its movement compared to that of our canine clock...

Well those S.C.A.P.H. folks were artisans.

I will separate those plates.