The next item is watt link of SSWork. From Japan
By the pros
Normal of the undercarriage, hard coil, general coil, time it collapses - stretch It will sweep to the bend.
It will cause the shaft to move its left-right side along its sweep.
But Watt's link, it will keep the shaft does not move the left-right side better.
In the short-term collapse, it will hardly move at all. Improved access to the curve.
The disadvantages are only tight. Is very high maintenance