Rolex 5055

History: In 1977, the Cal. 5055 was launched to power the Day-Date models. As you would expect, while it was clear Rolex was only getting involved with this new technology under duress, what they came up with became the standard for others to follow.

Rather than trying to reinvent the wheel, the Cal. 5055 was constructed as much as possible along the same lines as the mechanical movements Rolex had been dominating the industry with for decades. The bridge, gear train and pallet assembly would be recognizable to anyone with a passing familiarity of the inner workings of a Submariner or Explorer. In fact, the entire drive mechanism of the 5055 is based very much on a traditional escapement and, with the exception of the pulse motor and electronics, the movement is almost identical to the mechanical Cal. 3035 launched the same year.

The drive mechanism for the 5055 is very similar to the design of a traditional mechanical watch escapement. The pulse motor drives a pallet fork which in turn moves a pallet wheel. This wheel drives the second hand at a 1:1 ratio with one tick per second. The hour and minute hands are driven off this pallet wheel. The loud "tick" you hear every second are the pallets engaging the pallet wheel.

Manufacturer: Rolex SA (/ˈroʊlɛks/) is a Swiss luxury watchmaker. The company and its subsidiary Montres Tudor SA design, manufacture, distribute and service wristwatches sold under the Rolex and Tudor brands. Founded by Hans Wilsdorf and Alfred Davis in London, England in 1905 as Wilsdorf and Davis, Rolex moved its base of operations to Geneva, Switzerland in 1919. Forbes ranked Rolex 64th on its 2016 list of the world's most powerful global brands.[Rolex is the largest single high end watch brand. The company is owned by the Hans Wilsdorf Foundation, a private family trust.

Alfred Davis and his brother-in-law Hans Wilsdorf founded Wilsdorf and Davis, the company that would eventually become Rolex SA, in London, England in 1905. Wilsdorf and Davis' main commercial activity at the time involved importing Hermann Aegler's Swiss movements to England and placing them in high-quality watch cases made by Dennison and others. These early wristwatches were sold to jewellers, who then put their own names on the dial. The earliest watches from Wilsdorf and Davis were usually hallmarked "W&D" inside the caseback.

From Wikipedia