Monopusher (Single-Pusher) Chronograph Watch Movement

Some of the topics covered in this caliber listing:

What is a mono-pusher?

A monopusher is sometimes also called a single-button chronograph. It is when a watch with a chronograph complication has one button instead of two. While this design seems new to the market of modern wristwatches, it is actually found in antique pocket watches from a century ago. Modern watch brands like Cartier have had their Monopoussoir calibers, but not until ebauche-esque offerings from Sellita have they hit the mass market.

How does it work?

Modern chronograph watches as we know them today, have two buttons: one above the crown and one below the crown. For example, whether on the automatic caliber 7750 or the quartz VK64, you will press the top button to start and stop the chronograph timing mechanism, then press the bottom button to reset it.

For monopusher watches, there is only a single pusher used to operate the chronograph function. This button can be found above or below the crown, but is also sometimes built into the crown, allowing for a chronograph with a seemingly buttonless case design.

Monopusher watches:

Here is a short list of a few modern watches with the monopusher complication.

Longines Heritage Series: Longines also has a few monopusher watches from the Avigation to the Pulsometer single pusher. These watches use the Longines caliber L788, based on the ETA Valgranges caliber A08.L11. This is a cool line of watches given that Longines claims to be the first company in the world to make a chronograph wristwatch in 1913 (it had a single pusher). Previous to that, chronographs were in the form of pocket watches.

Montblanc 1858 Monopusher: Montblanc has a few options for monopushers, some with the button above the crown, others with the button built into the crown. For example, caliber MB M13.21 is a manual-wind single-button chronograph movement with the chrono pusher placed above the crown. Caliber MB 25.12 is an automatic single-button chronograph with the button integrated into the crown.

Farer Segrave Monopusher: Farer has a few single-button chrono options in their lineup, all using the Sellita caliber SW510 MP. As you can guess, the MP stands for Monopusher.

IWC Portofino Monopusher: IWC offers a Portofino chronograph with a single-button design. The hand-wound IWC caliber 59360 features a pusher that is built into the crown.

Bell & Ross Vintage Monopusher: The Bell & Ross monopusher is powered by an automatic La Joux-Perret Caliber 8201 MPC with the chronograph button built into the crown.

Alpina Startimer Pilot Monopusher: Alpina’s single-pusher chronograph is powered by a caliber Alpina calls the AL-727, which is bascially a La Joux-Perret caliber like the B&R.

Cartier Mono Poussoir: The Cartier Monopoussoir (pictured above) is probably the most elegant with how they pull off the monopusher. The button is integrated into the crown, but instead of there being a button sticking out of the center of the crown, the entire crown can be pressed in, giving a clean buttonless appearance. Cartier offers a few models with single-button chronograph technology, including timepieces from the Tortue and the Tank lines. Read more about the important Cartier caliber 045 MC here.

Ulysse Nardin Monopusher Chronograph: The Ulysse Nardin monopusher uses the caliber UN-38, based off of the same base movement found in the Cartier mentioned above.

Patek Philippe 5372P – In their latest monpusher offering, Patek has a manual-wind caliber CHR 27‑525 PS Q boasting a full set of calendar complications: day of the week, date, month, day/night indicator, leap year, and small running seconds.

Monopusher Calibers:

Aside from the brands that developed their own in-house single-button chronograph movements, many of the monopusher watches currently on the market are powered by some variation of the Sellita caliber SW510. The Alpina and Bell&Ross models are powered by the La Joux-Perret Caliber 8201 MPC (or MP), a movement manufacturer owned by Citizen. Swatch Group brands like Longines are likely using the ETA Valgranges caliber A08.L11.

Brands such as Montblanc, Alpina and Longines may designate their own caliber number to their watches, but other than branding on the rotor, different finishing or adjustments made, they are using a base caliber. Out of all of the monopusher base calibres, the one that is available is the Sellita SW510 MP/MPC.

What this also means is that the monopusher style of watch can be done by microbrands on a smaller scale than before. So, if you are looking for a modern monopusher movement for a bench project or to launch a small watch brand, look into the Sellita SW510, which is available in automatic or manual-wind.

Understanding the Sellita SW510 monopusher options:

Sellita really dropped the ball on the caliber SW510 in terms of ease of distinguishing the multiple variations. It’s understandable that they are all based on the SW510 framework, but since some of the options are so dramatically different, it would have been better if they added numbers to the “SW510” base by using SW511, SW512, SW513 and so on. Instead, what we get is the mess outlined below. You will quickly see that it makes it difficult to decipher what you are getting when brands and sellers simple put “SW510” in the descriptions. Note: The SW510 family is so confusing and also includes non-monpusher calibers (two buttons), but for the purposes of this post, we’re talking only about the single-button options.

Sellita’s Automatic Monopusher Caliber Numbers:

SW510 MP a – Single pusher at 2:00, small running seconds at 9:00, central sweeping chronograph seconds hand, 30 minute chronograph counter at 3:00, date at 6:00.
SW510 MP b – Same as above, but without a date (meaning no ghost date).
SW510 MP c – Single pusher at 2:00, date at 9:00, central sweeping chronograph seconds hand, 30 minute chronograph counter at 3:00, no small running seconds subdial.
SW510 MPC a – Single pusher built into the crown, small running seconds at 9:00, central sweeping chronograph seconds hand, 30 minute chronograph counter at 3:00, date at 6:00.
SW510 MPC b – Same as above, but without a date.
SW510 MPC c – Single pusher built into the crown, date at 9:00, central sweeping chronograph seconds hand, 30 minute chronograph counter at 3:00, no small running seconds subdial.

Sellita’s Manual-Wind Monopusher Caliber Numbers:

SW510 M MP a – Single pusher at 2:00, small running seconds at 9:00, central sweeping chronograph seconds hand, 30 minute chronograph counter at 3:00, date at 6:00.
SW510 M MP b – Same as above, but without a date (meaning no phantom date).
SW510 M MP c – Single pusher at 2:00, date at 9:00, central sweeping chronograph seconds hand, 30 minute chronograph counter at 3:00, no small running seconds subdial.
SW510 M MPC a – Single pusher built into the crown, small running seconds at 9:00, central sweeping chronograph seconds hand, 30 minute chronograph counter at 3:00, date at 6:00.
SW510 M MPC b – Same as above, but without a date.
SW510 M MPC c – Single pusher built into the crown, date at 9:00, central sweeping chronograph seconds hand, 30 minute chronograph counter at 3:00, no small running seconds subdial.