Technical Notes: Column Wheel vs Cam Actuated Chronographs

In March of 2013, the script was flipped on the history of the chronograph. The previous belief of the chronograph’s origins was with Nicolas Rieussec, who developed the concept of a device known as a tape chronograph, which recorded time intervals with ink. Some 20 years later, in 1844, Adolphe Nicole developed the “zeroing” function, which is sort of the key to a modern chronograph. And thus, the chronograph took shape; or so everyone thought.

It turns out, Louis Moinet (who’s name is still carried on by a modern day watchmaker) may have created the first chronograph in 1816, a full five years ahead of Rieussec. What’s more, Moinet’s example had a zeroing function, and could measure time down to the 1/60^th of a second – quite impressive, considering no one would touch that degree of accuracy until Heuer got it to 1/100^th nearly a century later.

The last 200 years have brought many iterations and advancements for the chronograph. Today, the two most common types of chronographs can be grouped into cam actuated, and column wheel – the names describe the type of mechanism that controls the chronograph’s function. Generally speaking, we don’t feel that one type is necessarily better than the other, but there are distinct differences, which we break down below.

Column Wheel Chronograph

Girard Perregaux 1966 Column Wheel Chronograph — column wheel can be seen at the bottom part of the movement

The column wheel chronograph is widely thought of as the higher-end mechanism compared to alternatives. Reason being, it’s a bit more labor intensive to produce. Taking one look at the column wheel, you’ll notice the very tiny teeth (these are the columns) on one side of the wheel, making it look like the top part of a castle turret. These columns, when produced with a CNC machine, will likely end up with burring in various spots. While burrs are normal in just about any fresh CNC part, they must be smoothed out to ensure normal operation of the mechanism. Needless to say, removing burrs from in between the teeth is a tedious task.

Despite the manufacturing difficulties, the column wheel has one obvious positive attribute for the wearer. The pusher action is often very smooth (this, of course, assumes we’re talking about a quality watch to begin with). Another potential positive is actually not directly related to the fact that it’s a column wheel. When a column wheel chronograph features a vertical clutch (instead of a horizontally coupled chronograph), you will notice is how smooth the chronograph seconds hand jumps off from a stopped position – there is almost no noticeable ‘jerk’. The smooth action of the hand is achieved because the gearing is lifted in and out of place vertically, and the hand can stop and start precisely where it lays. Note that without the vertical clutch, a column wheel chronograph will likely still display a jump in movement, and not all are outfitted with this clutch system. In fact, horizontal clutches are often thought of as more aesthetically pleasing and are used in some high-end movements, despite any minor performance differences.

Diagram showing contact points for column wheel lubrication during servicing — courtesy of Al Archer

With the positives come the negatives. The labor-intensive nature of column wheel production unsurprisingly affects the bottom line price of watches powered by such movements. Although there are undoubtedly some excellent aspects of this type of chronograph, watchmakers have branded them as high-end to justify the price tags. Another issue is the delicate nature of the column wheel. It’s not unheard of for one of the teeth to break off – you probably don’t need an explanation for why that’s bad. And as far as servicing, watchmakers shouldn’t have much more trouble with a column wheel, except it might just be more time consuming.

Column wheel with broken column — courtesy of Al Archer

As stated, column wheel chronographs are often used in higher-end movements. Rolex’s caliber 4130 and the Zenith El Primero are probably the most widely known of their kind, along with Omega’s caliber 321 used in the original Speedmaster. With that said, you can find column wheel’s in less expensive movements from Longines, and even more cost-efficient in Seagull’s caliber ST19.

Cam Actuated Chronograph

Coming to the rescue of the budget conscious watch lovers is the cam-actuated chronograph. In place of the column wheel mechanism, you’ll find a series of levers and arms meshed together and driven by a cam. The nature of its construction allows for more “play” in the parts, versus the highly precise construction of a column wheel. The levers and arms are much simpler to produce, cutting down overall costs tremendously.

Omega Cal. 1861 — levers can be seen on the upper half of the movement

As far as performance, a cam-actuated chronograph stacks up just fine against the column wheel. Hell, if NASA was willing to approve a cam-actuated chronograph for space flight, how bad can it be? The simple construction, production, and lower cost lend to more robust situations, like military use. The performance will be accurate and reliable enough for just about anything, and, if it breaks, the cost of replacing it is a much easier pill to swallow. But not going as far as breaking, servicing a cam-actuated chronograph is rather simple. The nice flat surfaces and lack of tight angles on the arms and levers makes for quicker cleaning and lubricating.

Cam switch lubrication contact points — courtesy of Al Archer

Part of the “high end column wheel” marketing strategy is to say cam-actuated chronographs aren’t haute horlogerie. Technically, this is true, because creating something simpler and less elegant is counter to the haute horlogerie mantra. However, this shouldn’t matter to most folks, as long as they know they’re getting a quality product regardless.

When it comes to actual negative characteristics, well, there isn’t much to complain about. If we’re getting nit-picky, cam-actuated chronographs tend to have a tougher pusher feel. Thinking about it mechanically, when the pusher is depressed, it turns the cam on its axis, and therefore requires more force. Hence, the stickier feel.

One of the biggest flaws blamed on the cam-actuated chronograph is misattributed. They are often described as having a jumpy chronograph seconds hand upon engaging the function. This is actually due to the fact that cam-actuated chronographs typically feature horizontally coupled drive gears – it has nothing to do with the cam, levers, and arms. On a horizontal clutch, the driving gears are meshed together upon engaging the chronograph, which can make the seconds hand appear to skip a bit depending on how the gears are positioned during the coupling. The confusion likely comes from the fact that there aren’t any cam-actuated chronographs with a vertical clutch (well, at least none that we can find).

Since cam-actuated chronographs are less expensive, you probably won’t be surprised to find out that the most ubiquitous chronograph movement in the world features it: the ETA 7750. That also means that just about every single variation of the 7750 will work off of the same mechanism (with some exceptions from Longines and La-Joux Perret). The other most notable example of a cam-actuated chronograph is the current Moonwatch. When Omega switched over to the caliber 861 (and now 1861), they opted for a cam instead of the caliber 321’s column wheel. If anything shows the lack of quality difference between the two systems, space flight certification is probably it.

We hope the content here is helpful for many of you, as the detailed mechanics of chronographs can get pretty perplexing. This was a great opportunity for us to really get into the weeds and we plan on doing more of it in the future. Finally, we’d like to thank Al Archer for providing pictures and lots of technical information for the article – this would have been really tough to do without him, or, at least tough to do accurately.

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