The RM 004 and RM 008 are both split-seconds wristwatches with virtually the same mechanical layout and design. The only significant technical difference between them is that the RM 008 is driven by a tourbillon escapement. The implementation of a carbon nanofibre baseplate in the development of the RM 003 required an almost total revision of its structural design and assembly methods, while in the highly complex RM 004 with its deep-set movement bridges, this represented a major and daunting challenged that required years of research and development.
Manual winding movement with hours, minutes, seconds, split-seconds chronograph, 30-minute totaliser, power-reserve, torque and function indicators.
The first batch of RM 004s produced were equipped with complex movements that used the same titanium baseplate design seen in the first RM 002 and RM 003 tourbillons. But its design was very quickly redeveloped to incorporate carbon nanofibre. The RM 004 as a timepiece for connoisseurs of complex watches was already a rare item within the RM collections, and that meant very few titanium baseplate versions of the RM 004 were ever created before the switch to the RM 004-V2 version was made. As a result, RM 004 timepieces featuring titanium baseplates are now some of the rarest serial-produced Richard Mille timepieces.
The design of the RM 004 witnessed continuous incremental technical refinements in the years following its release. One unexpected issue identified early on was an unusual magnetism being created in some watches. It was only several months later that we discovered that the fast-moving chronograph hands turning above the carbon nanofibre inserted between the front and back sapphire crystal of the case was generating a build-up of static electricity, which was inadvertently causing the steel hands to magnetically charge the movement. Once the cause had been identified, the simple solution was to use titanium hands instead, and the brand retrofitted this solution to all RM 004 watches already delivered to customers.
The latest official revised version, the V3, appeared in 2016, with a deeply reworked movement incorporating the multiple new developments implemented in the RM 50-02 Airbus watch. The movement engineers continued along their path to refinement by separating the reset lever from the leaf spring for better control of the reset function and by incorporating an adjustable clutch rocker to minimise jumps when the chronograph is started. Modifications were also made to the hammer stop, and a new slide to optimise the drive of the minutes counter was also integrated.
For enhanced rigidity, the aluminium centre bridge, platform escapement, chronograph and split-seconds bridges were replaced with bridges in Grade 5 titanium. Further minimalist improvements to tiny details continue and are implemented when watches return for regular servicing.