Cal. MT5813 is an automatic chronograph movement from Tudor derived from the Breitling Cal. B01.
It is a modern movement, with a column wheel and vertical clutch. Cal. MT5813 has a modular design, allowing the chronograph mechanism to be separated from the base timekeeping unit for repair or replacement. It includes a silicon hairspring, resistant to magnetism, as do many Tudor and Rolex movements. Power reserve is 70 hours.
Although not an in-house design, Cal. MT5813 shares some architectural similarities to Tudor parent Rolex’s Cal. 4130. It is said that many of the same engineers worked on both movements, so it is interesting that the design would come back to Tudor by way of Breitling. It is constructed by Breitling for Tudor at a dedicated facility in La Chaux-de-Fonds, not far from the new Tudor manufacture in Le Locle. The movement is mechanically finished in a simple manner, with sandblasting and graining unlike the Breitling example, and features a Tudor-style winding rotor. Unlike the Breitling, the Tudor movement uses a free-sprung balance with four adjustable inertia blocks.
The movement powers two subdials:
- 45 minute counter at 3:00
- Small seconds at 9:00
Many online sources list the diameter of the movement as 33.8 mm, the same as the larger members of the MT56 family. Official sources, however, list it at 30.40 mm diameter and 7.23 mm thick. This is closer to the dimensions used by Breitling for their Cal. B01, 30 mm and 7.3 mm.