Service: Cauny Dress Watch with AS 1950/1951 Movement

 In Watchmaking

I got this watch in a batch from a collector to take a look at. Sadly, two of the four watches were too far gone but this is one of the two watches that could be saved.

It’s a Cauny dress watch with an AS 1950/1951 movement which dates it to the late 1960s or early 1970s. Looking at the style of the dial, I’d say early 1970s. The watch didn’t run because it was impossible to wind.

Disassembly

Usually, you need to remove the power from the mainspring before you disassemble a movement. In this case, that isn’t necessary because it’s impossible to wind the watch.

The crown turns, but you can feel the watch snap back to the original position as soon as you let go of the crown. That suggests a problem in the winding assembly.

Remove the balance, the balance cock, and the pallet fork and store them somewhere safe.

Cauny dress watch with AS 1950/1951 movement

The balance and the pallet fork removed. You can tell that there’s no power in the mainspring because the click isn’t in the locked position.

Remove the ratchet wheel and the crown wheel with the crown wheel ring. The crown wheel has a left-handed screw.

Cauny with AS 1950/1951 movement

The ratchet wheel and the crown wheel with its ring removed. It’s hard to tell on the picture, but the click is in a strange position.

Looking at the winding assembly, it’s clear what happened. The click has a lot of vertical play, and at one point the click spring slipped underneath the little pin of the click. At the moment it doesn’t force the click into the “locked position.” It holds the click away from the ratchet wheel like you’d do manually to release mainspring tension.

Take out the click with its screw and the click spring.

Lift the wheel-train bridge to gain access to the wheel train.

Cauny with AS 1951/1951 movement

The click and the click spring removed. With the wheel-train bridge lifted, you can access the wheel train.

At this point, you can remove the barrel bridge and lift the barrel.

The wheel train is fascinating in this particular movement. Usually, the friction is given by the cannon pinion on the center wheel. In this case, it’s given by a friction pinion on a driving wheel. The AS 1950/1951 doesn’t even have a center wheel.

So, lift the escape wheel, the third wheel, and the sweep second wheel. You can’t remove the driving wheel at the moment because it’s secured with the friction pinion on the dial side.

Cauny with AS 1950/1951 movement

Turn the movement around and start with the motion works.

Remove the hour wheel and cannon pinion guard. Lift the minute wheel but be careful because it’s held under tension in this movement. It makes sure that the minute wheel keeps in contact with the friction pinion and the cannon pinion. Make a note or take a picture so you can place the wheel on the right side of the spring during reassembly.

Take out the set lever spring, the return bar, and the return bar spring. Loosen the set lever screw and take out the winding stem, the castle wheel, and the crown wheel. Remove the set lever and its screw.

Finally, use a Presto puller to remove the friction pinion, and the driving wheel should fall on the bench mat.

Cauny with AS 1950/1951 movement

Preclean all the parts with peg wood and clean them in the watch cleaning machine. I like to clean the case and polish the crystal when the parts are being cleaned.

Reassembly

It’s a good idea to install the set lever and the set lever screw first because it can be a fiddly job.

Fit the barrel and place the escape wheel, the third wheel, the driving wheel, and the sweep second wheel in position.

Place the wheel-train bridge over the wheels. Put some very light pressure on the wheel-train bridge with a watchmaker’s pick or a piece of peg wood. Wiggle the wheels with your tweezers or an old oiler until they’re all in the right position.

Keep some light pressure on the wheel-train bridge and keep testing the wheels while you screw it down. If the wheel train suddenly stops spinning, something isn’t right.

Cauny with AS 1950/1951 movement

Reinstall the barrel bridge and the winding assembly. Remember that the crown wheel is a left-handed screw. I fitted a new click and click spring otherwise the same thing could easily happen again.

Cauny with an AS 1950/1951 movement

The barrel bridge and the winding assembly reassembled. The default of the click is now the “locked” position as it should be.

Turn the movement over and begin with the motion works. Place the cannon pinion, the minute wheel (remember to put it on the right side of the spring), and reinstall the cannon pinion guard.

Place the friction pinion over the driving wheel post and press it down as you’d typically do with the cannon pinion. Use brass tweezers, so you don’t damage the movement.

Move to the keyless works and reinstall the castle wheel, the crown wheel, the winding stem, the return bar, the return spring, the setting wheel, and finally the set lever spring.

Cauny with an AS 1950/1951 movement

The dial side reassembled except for the hour wheel and the dial washer. The red arrow is pointing at the friction pinion which also functions as an intermediate wheel.

Flip the movement to the top plate and reinstall the pallet fork with the pallet cock. Reinstall the balance, and the movement should come alive. You might need to jumpstart it with a little flick.

As you can see, this AS 1950/1951 has shock-protection. It looks like Ruby Shock but there are a few that look very much alike. Hold the spring with a peg wood and turn it until one of the feet reaches the little notch. When one of the feet is loose, you can lift it.

Clean and lubricate the cap jewels and replace them. Install the springs in the reverse order.

Place the hour wheel and a dial washer in position and fit the dial and the hands.

Cauny with an AS 1950/1951 movement

What do you think of this Cauny? Do you have a similar one? Let me know in the comments below.

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    Chayal M L
    Reply

    Very informative as always.
    Thanks Melvin,
    Regards,
    Chayal

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