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Rolex - 2940 - Oyster Perpetual - Bubbleback

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Rolex - 2940 - Oyster Perpetual - Bubbleback
Name 2940
Family Oyster Perpetual
Subtype Bubbleback
Movement Rolex 630 (Details)
Case Diameter (mm) 32
Mechanism Automatic
Chronometer No
Hacking No
Date Function No
Quickset No
Power Reserve (Hours) 41
Frequency (bph) 18,000
Jewel Count 17
Band Size 17
Band Replaceable No

Notes: Following the introduction of the Oyster case in 1926, Rolex turned their attention to the development of the automatic movement. Although they were not the first to manufacture an automatic wristwatch, Rolex were the first to perfect its use. Although Rolex’s automatic rotor system was developed in 1931, it does not appear to have been introduced until the end of 1933. Indeed, the first advertisements for the models were not published until 1934.

These second generation watches from Rolex were introduced a decade after the company’s first automatic movements. These models are known to collectors as “bubble backs” and are amongst the most iconic and collectible of all vintage Rolex watches; their domed backs, from which they gain their nickname, is rounded in order to incorporate the automatic rotor which sits above the movement’s back-plate. Throughout, this watch is in excellent condition for its age, the original dial has only very light and even oxidation across the surface and the case retains excellent definition to its angles, edges and the milled case back and the case number between the lugs remains exceptionally clear.

Th 630 was Rolex's second automatic mechanism. It was an evolution of the 620. It is a self-winding movement with unidirectional winding rotor, 18,000 A/h, 17 jewels, small seconds, shock protection. Escapement: Stone lever, Yoke winding system. Sweep second. first automatic with rotor winding. Breguet hairspring.

Type: The Rolex Bubble Back or Bubbleback was first manufactured in 1933. These watches got their name due to the fact that the auto wind mechanism appeared to simply be bolted onto the basic Rolex movement. This attachment was rather large so it was necessary to round out the case back in order to accommodate the mechanism in order to allow proper functioning of the oscillating weight which made complete 360 degree rotations within the case. The Rolex Bubble Backs were produced possibly as late as the early 1960's. Many good examples exist to this day possibly due to the simple and durable basic 18 jewel design of the movement.

Most of these watches were time only and also had a sweep second hand. Later models included a date mechanism and were possibly the first DateJust models produced by Rolex such as the model 6075 which was manufactured in 1948. Some of these early Bubble Backs also had subsidiary seconds bits and many also had the popular California dials which had both Roman numerals and Arabic numerals. None of the Bubble Back cases had bezels that could be removed. Rather than the watch crystal being held in by compression using a bezel crystals were installed by the constriction method. The most common crystal used for these watches is the Tropic 30 crystal. It measures 2.6mm in height. The inside diameter is 24.6mm and the outside diameter is 25.5mm. The Bubble Back shown below has a Registered Design of 6015. Case sizes for the gents watch is 31mm, the ladies is 24mm. Lug sizes for the gents watch is 16mm and the ladies is 13mm.

Item created by: gdm on 2018-09-29 19:59:38. Last edited by gdm on 2018-10-02 10:35:47

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