I was curious about why lifts share a tower, and more importantly how it works, and how it affects both lifts.
For instance, take these lifts:
Snubber & Sawduster at Sugarloaf. (The only cross manufacturer combination I have seen)

The Summit Triple & Flying Yankee at Attitash:



So my questions are:
1. How is the tower extended to make way for the other lift crossing over on the same tower? I would assume that you either replace the entire tower, or add another tower tube on top of the old one if that's possible
2. How does the cross-manufacturer tower work? Does anyone know if the tower is stadeli or borvig?
3. How does this affect the lifts?
By the way, to prevent any confusion, i'm not talking about double-doubles.
Thanks