Why is the column wheel considered so important? Surprising facts about chronograph parts

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2022.06.03

omega

Q: Is it really true that watch experts say, "Choose a column wheel chronograph"?

Watch enthusiasts often say that when purchasing a chronograph, they are concerned about whether it is a column wheel or a cam mechanism. Of course, both can operate a chronograph, but is there an advantage to one over the other?

Article published on June 2022, 6

A: A column wheel that allows for fine control and a cam that can be made inexpensively

　A watch with a stopwatch is called a chronograph. In the case of mechanical watches, there are two ways to control the stopwatch: the column wheel type, in which a cylindrical "control tower" rotates to start and stop the chronograph, and the cam type, in which a plate-shaped part moves left and right.

　Currently, almost all so-called high-end mechanical chronographs use a column wheel, while the only movements that use a cam mechanism are the ETA7750 (and its replacements), a standard in automatic chronographs, and Omega's Cal. 3861 and Cal. 1861, which are used in the Speedmaster series.

Omega 321

The original Omega Cal. 321 movement. It uses a column wheel to control the start/stop/reset of the chronograph. When the Cal. 321 was later replaced by the Cal. 861, the control method was changed to a cam mechanism.

　The column wheel type, which uses a rotating cylindrical part, is characterized by its ability to precisely control the movement of the lever. However, on the downside, it is expensive to manufacture. Cam types, on the other hand, are the opposite of column wheels. They are inexpensive to make, but because the control is rough, it was considered difficult to add a brake lever to firmly stop the chronograph. As a result, chronographs without brake levers will move if they receive a strong shock. This is why the cam type was once considered cheap.

Currently, column wheels and cams are no longer superior.

　However, it is no longer necessarily the case that the column wheel is superior. In 1968, Omega equipped the Speedmaster with the Cal. 861, which was a cam mechanism but also had a brake lever. The ETA 7750, released in 73, also had a cam mechanism, but it was equipped with a proper brake lever. It can be said that today there are no mechanical advantages or disadvantages between the column wheel and cam mechanism.

Photograph by Yu Mitamura

The reason cam mechanisms were once considered inferior to column wheel mechanisms was that they could not be equipped with brake levers. However, Omega's hand-wound chronograph movements using carrying arms solved this problem, and have continued to use cam mechanisms since the Cal. 861. The latest movement, the Cal. 3861, which has been converted to a co-axial movement and now uses a silicon balance spring, has not changed this policy, so it is clear that there is no superiority between the two.

The Truth About Cam and Column Wheel Chronographs in Mechanical Watches