Let's set the scene. The ubiquitous Valjoux (ETA) 7750, which is, one way or another, the base of the IWC 80110
, uses a tilting pinion strategy to operate the chronograph centre seconds. The tilting pinion in the 7750, # 8086 in the schematic below, is carried by the tilting pinion arm and is continuously driven by the fourth wheel (# 224). As the chronograph function is only designed for occasional use, the lack of jewels present in this driveline to provide centre seconds (# 8000) is not an issue.
Sadly, the IWC 80110 use the same 'nasty' design for the indirect centre seconds via pinion transfer as described above as can be seen here
. The key issue is that in the 80110, the pinion is fixed (as opposed to tilting in the 7750), and rotating several times a minute, (8 so I'm told), forever. (Peter CDE's article
showed the whole movement.) So, have IWC at least jewelled the bearings?
So, it looks like, "Yes," but with a caveat. For comparison here is the kind of thing IWC have avoided:
Above, is a standard 7750 pinion carrying arm and the jewelless bearing - eughhhh. I mean imagine spending $7200 and getting that...... Fortunately IWC have done the right thing and jewelled the transfer pinion top and bottom and the centre seconds wheel is jewelled at the top. What is not clear is whether it is jewelled at the bottom or retains the standard 7750 plastic bearing shown below:
Several years ago, Michael Friedberg (official IWC forum moderator) asked the technical director at IWC if the JLC-base in the Mark XII was superior to the ETA base in the Mark XV because the JLC movement had more jewels. He responded,
"...jeweling is not necessarily better --sometime they cracked and the design issues were far more complicated than that. ......metal bearings sometimes (but not always) were sturdier and that it often didn't matter since they would be replaced during routine servicing."
Hmmm, metal bearings make sense (and such bushes are used by some manufacturers) in areas of high torque load and low speed, but with very low torque levels and high rotational speeds (in the parts we're referring to, i.e. counting seconds) we want low friction and hard wearing; the properties provided by ruby.