Exceptional Movements In History: Rolex Caliber 1575, The Watchmaker’s Watch
by Ashton Tracy
Rolex is known for producing quality, dependable movements that get the job done. We need only survey the brand’s current lineup of calibers to see that for the last several decades, quality and functionality have been at the forefront of Rolex engineering.
The 3135 introduced in 1988 has been the workhorse behind so many models as the base caliber for complications including second time zone and day/date.
From Kristian Haagen’s ‘Hashtags and Watches’: a Rolex Sea-Dweller Rail Dial Reference 1665
In recent years, however, the 3135 has taken a backseat in lieu of the 32xx family, which has started to shine. It is my educated assumption that the 31xx movement family will be completely phased out in coming years, to be entirely replaced by the 32 series.
But a long time ago, before these movements reigned supreme, the Rolex world relied on the 15xx series to keep it on time.
Rolex Caliber 1575
As far as automatic watch movements are concerned, the Rolex 1575 is the cream of the crop: it has it all. It’s hard wearing, robust, elegant (ish), and an exceptional timekeeper.
Rolex Caliber 1570 with automatic winding mechanism removed
Interestingly, when these movements leave a Rolex service center after an overhaul, they are sent out to run within C.O.S.C. specifications, meaning to gain two seconds per day. That’s quite a feat for a watch of that age; different brands’ watches of similar pedigree don’t produce those results many years later that I’ve seen.
Rolex Caliber 1575: brief history
The 1575 was launched in the mid-1960s. As it movement it doesn’t have a particularly grandiose history; Rolex produced it because it needed a reliable, robust automatic watch. And, boy, did it deliver. Job done.
Caliber 1575 was based upon the Rolex 1560 movement, but improvements were naturally built in. The 1560 had a frequency of 2.5 Hz and a power reserve of 44 hours. When the 1575 was launched it was based heavily on the 1560 but with a few upgrades; most notably a four-hour power reserve increase, a frequency increase to 2.75 Hz, and hacking seconds.
Rolex Caliber 1575: movement specifics
The 28.2 mm diameter movement features 25 jewels, date display, and overcoil balance spring.
The finishing is nothing to write home about as functionality was definitely at the forefront of the designers’ minds. The main plate features a spotted pattern, and the bridges boast a lightly grained finish.
Rolex Caliber 1570 dial side
Functionality and ease of repair are where the 15 series family shines. The barrel bridge is solid, yet not cumbersome, housing only the barrel underneath. The train wheel bridge secures all the train wheels under one roof, as it were.
Of particular note is the shock protection feature for the escape wheel. It is an unusual feature that is most commonly saved for balance wheel pivots. I have seen it on other calibers, but rarely and only on the movement side, which indicates it’s for show more than functionality. With this Rolex caliber, however, we see the escape wheel on both dial and movement side.
Its escape wheel pivots are fine in nature, and I find that having this extra protection is a definite positive. This is a feature Rolex uses down to this day in most, if not all, of its movements.
Rolex Caliber 1570 balance from the back
The balance features timing screws plus two microstellar nuts to adjust timekeeping. These nuts are turned either clockwise or counterclockwise to adjust the rate of the watch, depending on what is needed.
The 1575 uses a free-sprung balance, which means regulating pins are not required. Regulating pins are used to control the active length of the hairspring, thus determining timekeeping. Their downfall is that if the watch receives a shock the pins can move, resulting in a timing error. With a free-sprung balance that can’t happen as there are no pins; timing is controlled via the balance itself.
The oscillating weight is heavy and has the mass to get the job done. It features a center axle rather than ball bearings, and is held in position by two ruby jewels, thus reducing friction and improving performance. This again is a feature that Rolex used throughout the 30 and 31 caliber families.
Much like the oscillating weight and shock protection for the escape wheel, the instantaneous date function of the 15 family is something Rolex uses to this day.
Firstly, though, let’s get this out of the way: there is much confusion about the date model for the 15 series, but do note that the 1575 is not a GMT movement; it is a date-only model.
The movement called “1575 GMT” is the one that features a GMT complication.
And to further complicate things: when the watchmaker opens a watch powered by a 1575 movement, the bridge may well be stamped “1570.” This is not incorrect; it is merely something that happened back in the day.
Rolex Caliber 1570 with date ring
The date changes at midnight and it does so instantaneously using a cam, spring, and jewel. The cam has a cutout for the jewel to sit neatly within, and as the watch gets near midnight the lever with the jewel attached is forced into the cutout of the cam, enabling the date to change at exactly midnight.
Rolex Caliber 1575: conclusion
The 1575 is most definitely the watchmaker’s watch. It is a pleasure to work on, can be made to perform exceptionally decades after production, and never becomes tedious.
It is also the consumer’s watch as it keeps great time, remains as robust and reliable as when it left the factory floor, and it simply gets the job done. It might not be the most elegant or visually appealing movement in history, but when something needs doing right, it gets the job done.
Just ask the Explorer II, the original Sea-Dweller, or even the Submariner.
Quick Facts Rolex Caliber 1575
Production years: 1965-1981
Winding: automatic
Frequency: 2.75 Hz/19,800 vph
Diameter: 28.2mm
Height: 6.3 mm
Jewels: 25
Power reserve: 48 hours
Functions: hours, minutes, center seconds, date
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I have a 1675 with the 1570 movement hasn’t been opened for over 10 years and it runs under COSC. It’s the most accurate and oldest watch I own along with a new Seiko Presage.
Great movement no doubt. It does lack jewels for the barrel in bridge and plate. Also the center wheel is a weak spot for wear. The rotor is held in place with a clip spring to control the ends hake, not jewels as mentioned in the article.
There seems to be used a higher quality steel in the automatic winding than used in newer calibers. Oh, and the daydate function is loathed by most watchmakers because of the flimsyness.
If you want to make sure this movement doesn’t eat itself be absolutely sure to get it serviced. Heavy duty movements like these tend to keep on Going for far to long and in conjunction with what I stated before, worst case the main plate needs to be exchanged.
The rotor is indeed held in place by a clip spring. It is also, however, held in place by two jewels, one in upper and lower automatic bridges. The clip spring is what stops the rotor coming out of position in the plates, the jewels ensure the a snug fit for the axle. This is the same set up on the 3035 and 3135, and that’s what once am referring to. Hope that clears up the confusion.
No need to replace mainplate, Rolex made a tool they call minilathe. With it you drill out and fit beryllium bushings for barrel and centre wheel. All bigger Rolex service points have it.
I thought free sprung balances had an advantage over curb pins in that curbs interfere with the overcoil and thus alter its isochronal properties. The lack thereof also reduces untrained hands from meddling.
You mean hairspring or you really mean overcoil?
Great article! I’m just learning about movements, and this was a great help to me. I’m currently wearing my father’s 1575 date. Just had major service. Runs, as you would expect, within a couple of seconds a day.
I am in need of a 1575 or 1565 movement, if anyone has one, that they’d like to sell. Please. Thanks in advance
I have a 1570, which as understand it, is the base movement for the 1575. To work as the 1575, you would also need a date wheel.
I have a 1570 on my 1968 1675 GMT. Most reliable and robust movement in my whole collection.
We’re discussing another caliber here.
Nobody cares.