Reference:Movements: Difference between revisions

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Derived from the manual Cal. 600, Cal. 620 became the base for Rolex's early full-rotor automatic family. Antiquorum catalogues individual examples with 17 to 20 jewels, against the table's 17-jewel specification. Earlier 1940s movements have a swan-neck micrometer regulator without shock protection; by the early 1950s, an index regulator and shock absorber appear.

[https://ineichen.com/upload/iblock/2fe/sy5t0kgrsmh01eycyb7x6dv935lixtef.pdf Ineichen’s Auction 166 catalogue] identifies Cal. 620 in one 1940s ref. [[Reference:4643|4643]], case A60906 (p. 143). Keep that attribution with the auction lot; it does not establish a reference-wide caliber assignment.

The rotor is a unidirectional "Perpetual" type that turns through 360 degrees without bumpers or buffers. It is engraved "ROLEX PERPETUAL / CHRONOMETER / SWISS MADE / PATENTED / SUPER-BALANCE," while the three-screw, 18mm cover plate reads "VIS TIRETTE / PATENTED / TRIGGER SCREW." Cal. 620 powered early Bubblebacks. Rolex dates the introduction of its Perpetual rotor to 1931, but that historical account does not name the caliber. Cal. 630 and the related 635 and 645 developed from the same architecture.

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 Derived from the manual Cal. 600, Cal. 620 became the base for Rolex's early full-rotor automatic family. Antiquorum catalogues individual examples with 17 to 20 jewels, against the table's 17-jewel specification. Earlier 1940s movements have a swan-neck micrometer regulator without shock protection; by the early 1950s, an index regulator and shock absorber appear.
+[https://ineichen.com/upload/iblock/2fe/sy5t0kgrsmh01eycyb7x6dv935lixtef.pdf Ineichen’s Auction 166 catalogue] identifies Cal. 620 in one 1940s ref. [[Reference:4643|4643]], case A60906 (p. 143). Keep that attribution with the auction lot; it does not establish a reference-wide caliber assignment.
 The rotor is a unidirectional "Perpetual" type that turns through 360 degrees without bumpers or buffers. It is engraved "ROLEX PERPETUAL / CHRONOMETER / SWISS MADE / PATENTED / SUPER-BALANCE," while the three-screw, 18mm cover plate reads "VIS TIRETTE / PATENTED / TRIGGER SCREW." Cal. 620 powered early Bubblebacks. Rolex dates the introduction of its Perpetual rotor to 1931, but that historical account does not name the caliber. Cal. 630 and the related 635 and 645 developed from the same architecture.