There are a couple of points I’d like to touch on about the movement. First, unlike the 260-piece limited edition we saw at SIHH 2015, this version of the movement has no engraving on the balance cock (which is gold in the anniversary model). Another interesting point has to do with the system for activating the chronograph. Typically, in a lateral clutch chronograph like this one, you have the potential for a slight jump of the center chronograph seconds hand when the chronograph is engaged, as the teeth may strike each other tip-to-tip as the transfer wheel engages with the chronograph seconds wheel at the center of the movement. In the caliber 3300, the driving wheel (far left, above) is on the pivot of the fourth wheel, which turns once a minute; this driving wheel drives the transfer wheel, which is mounted on a pivoting lever. When you start the chronograph, the tip of the lever carrying the transfer wheel falls off one of the pillars on the column wheel, which allows the transfer wheel to drop into engagement with the chronograph seconds wheel. That’s where that little skip of the chronograph seconds hand could happen.
It’s far from the end of the, but it is a small bit of imprecision in a machine devoted to exactness, and it’s this little jump that a vertical clutch chronograph avoids. Now if you look closely at the transfer wheel above though, you’ll see that there’s another wheel directly under it, with Maltese-cross shaped spokes. This wheel is the one that actually engages the teeth of the chronograph center seconds wheel. Our guess is that there is a friction coupling between the upper and lower transfer wheels – Vacheron refers to a “friction system” in its press material that is supposed to eliminate the jump of the chronograph seconds hand – and that the lower gear drops into position when you start pushing the start/stop/reset button, but does not begin to turn until after the teeth are engaged; this would indeed eliminate the jumping chronograph seconds hand.