Rolex Cal. 3136 is an automatic movement with date used in the large Datejust II from 2009 through 2017. It is very similar to Cal. 3135 but has a larger main plate supporting a larger date wheel for the over-sized dial of the Datejust II. It also has Paraflex shock absorbers, which were used in other members of the Rolex Parachrom family but not Cal. 3135.
Cal. 3136 was only ever used in the Rolex Datejust II, Ref. 116300, which was produced from 2009 through 2017. The follow-on Rolex Datejust 41 shares the smaller 28.5 mm Cal. 3235 with other date-only Rolex watches.
Although produced for nearly a decade and used in a popular line of watches, there is very little information about Cal. 3136 available. Most reports say that it measures 28.5 mm in diameter, for example, even though it is visibly larger than the 28.5 mm Cal. 3135. There are also conflicting reports about the height of the movement, with some reports suggesting it is 6.47 mm thick, nearly .5 mm thicker than the similar Cal. 3135. Despite these reports, it seems likely that Cal. 3136 measures 30.97 mm in diameter (like the similarly-oversized Cal. 3187) and measures 6 mm thick.
As oversized watches became popular in the 2010s, Rolex created a group of special oversized movements. Cal. 3132, 3136, 3156, and 3187 all have a 2.5 mm wider main plate, bringing the movement dimension to 30.97 mm. This is not well-documented, and many sources list these movements at the Rolex standard diameter of 28.50 mm. The difference is obvious at a glance, however, with the wider flange visible in Rolex promotional shots and in the watches themselves. This larger size allowed the date wheel to be enlarged, moving the date display 1 mm further from the center on the large Datejust II and similar models.
Like other Rolex movements of the same era, Cal. 3136 features a free-sprung blue Parachrom hairspring with a Breguet overcoil attached to a Microstella balance. This is anchored to a full balance bridge and Paraflex shock absorbers are used. The winding system features deep red PTFE-coated winding wheels and the rotor is mounted on jewels rather than ball bearings.