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Calibre 860: a new expression of the chronograph
Adding a fresh chapter to the rich history of complicated calibres conceived and made in the Vallée de Joux, the Reverso Tribute Chronograph is powered by the new Jaeger-LeCoultre Calibre 860, a fully integrated hand-wound chronograph movement. Entirely designed, produced and assembled within the Manufacture, it is an elegant and creative answer to the challenge of housing circular chronograph timing indications within a rectangular case, while maintaining the clarity and legibility essential for this sporty complication. Moreover, according to Jaeger-LeCoultre’s approach to product integrity, whereby a movement should be shaped according to the case that houses it, the calibre itself also had to be rectangular. The result is a beautifully balanced and highly distinctive dial layout, with a large chronograph seconds display in the upper part of the dial complemented by a retrograde 30-minute indicator on an arc at the base of the dial.
Beating at 28,800 vibrations per hour, Calibre 860 incorporates a column wheel chronograph with a horizontal clutch, which was chosen over the more familiar vertical clutch to reduce the overall thickness of the movement. To display hours and minutes on both front and reverse dials, the movement powers two sets of hands that must move in opposite directions to indicate the time in correct clockwise fashion on both faces of the watch. Calibre 860 offers a power reserve of 52 hours, even allowing for the high energy requirement of a retrograde chronograph combined with two time indications. Despite this complexity and no fewer than 300 components, the shaped rectangular movement fully respects Jaeger-LeCoultre’s philosophy of elegance, fitting into a case less than 12mm thick.