Originally introduced around 1988 Rolex’s 3135 has been their workhorse movement since then. Of course things haven’t remained static these past 20 years and it has seen numerous improvements and upgrades in order to both refine and improve its performance and reliability. Like most Swiss watch companies Rolex doesn’t make a big deal of these upgrades, so most of the time even their own watchmakers are not aware of them, unless of course they are specifically instructed to upgrade the parts and movements when they come in for repair. Some of the improvements, like their new Parachrom hairspring, they choose to anchor to new marketing campaigns, in which case potential buyers now want to make sure that their new purchase has all the latest and greatest upgrades. But others, like subtle refinements to pivot and teeth shapes, improvements in the alloys of the metals used etc, often go unheralded.
Basic technical info for the 3135 Rolex movement:
Diameter = 28.5mm
Casing diameter = 28.1mm
Height = 6mm
Jewels = 31
Power Reserve = Approximately 50 hours