Skilifts.org / SORT Forum

Hey all

random question I have considered for a while now is about sheave assembly movement.
Mainly regarding one of my favorite lifts, it seems to me that when a chair comes out of the bottom terminal the first depression assembly seems to move downward with the rope. How is this accomplished? It's puzzled me since.

What you are seeing is an optical illusion. Most sheave assemblies pivot on a central axle- either extending from the cross-arm or in the center of the assembly if it is mounted on the cross-arm. As the weighted carrier comes out of the terminal the ROPE moves downward and the lead-in sheave frame follows the rope downward pivoting on the central axle. What you don't see is the the lead-out sheave frame moving upward as it pivots on the same central axle. (This is also why sheave assemblies are sometimes referred to as 'rocker assemblies' or 'sheave rockers')
Next time you are at your favorite lift, stand to the side and look at Tower 1 Depress and you will see what I'm talking about
Dino