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Chronograph Hour

2K views 14 replies 11 participants last post by  Brad605 
#1 ·
Is it normal for the chronograph hour hand to always move? Even when the stop watch is not running it counts the hours. The hand in the bottom circle.
 

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#7 ·
No, it should not do that. Will it rotate all the way around? Or does it only creep that far? An adjustment needs to be made to the movement, but I don’t recall what the issue is. I had the same issue on an Omega Speedmaster. The hour totalizer hand would creep a bit, but it would not make a full revolution.
Edit: I just searched “chronograph hour hand creep,” and there were a bazillion results (ironically mostly with Omega). Or just wait for a watchmaker to respond here.
 
#10 ·
No it's not. It does this because of how the hour counting wheel is driven, which is by a small pinion on the mainspring barrel. Here are the parts (under the dial and calendar platform):



The hour counting wheel is driven from this pinion that is on the mainspring barrel:



The barrel is mounted in the watch here, and the end of the arbor is noted by the arrow on the right - the left arrow indicates where the hour counting wheel sits:



Here is the pinion on the barrel, that drives the wheel:



This is the wheel - the silver part is what connects to the pinion on the barrel:



There is a plastic part (on this watch anyway) called the lock (B above) that puts pressure on the teeth of the hour wheel when the chronograph is stopped, but the pinion on the barrel is trying to turn the wheel all the time that the watch is running. The hour recoding wheel has a clutch system built into it with a friction spring:



This allows a part of this wheel to turn, an the rest to not turn when the chronograph is stopped, so two parts of this wheel are sliding past each other when the watch is running and the chronograph is not running. This feature also facilitates the resetting of the hour recorder. If the lubrication between the friction spring and the part is rides on has failed, often this will gum up and cause the wheel to be driven despite the lock being there to stop it. Although it's common for people to call for adjustments to the locking system (on watches that can be adjusted) or for parts to be replaced, often this hour recorder creep is solved simply by having a service done, cleaning this wheel, and renewing the lubrication so it slips properly.

If the lock does require replacing (rare in my experience) it's often done along with the hour recording wheel, and some brands sell these as a set of parts only.

So the bottom line is the watch needs a service likely, and as part of that service this problem will be corrected - likely without new parts but if they are needed they aren't expensive in the big picture.

Cheers, Al
 
#12 ·
Some early 7750s had a lock/brake with a smooth face that contacted the wheel. Later ones have a toothed surface. I doubt that Oris is old enough to have the early version, so Archer's assessment is almost certainly correct.

The spring "d" from Archer's photo can feasibly slip out of place on assembly but that would be evident with even a minimum of testing/observation by the watchmaker.
 
#13 ·
My Oris Diver Chrono has a broken movement. The small bottom chronograph hour hand doesn't stop running. It should only run when stopwatch function is on. So Oris's USA repair shop quoted me about $600 to take watch apart and completely clean, fix, lubricate, replace bezel insert and crown. Also warranty it for 1 year. It seems to sound pretty good. Any thoughts on it?
 
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