I'm doubting myself now wondering if I am getting confused and the clutch is actually on the chain. I see that many mechanical things, I get confused.
"Goes through paperwork".
The clutch is actually on the motor. As the train arrives, the train places tension onto the chain which activates the clutch and slows the chain. It then releases and rolls off like you say.
As the clutch is tension activated, that explains why it varies with different weights, specifically because the clutch must be worn out now.....the girlfriend must have been driving.
That makes more sense. A solution to the same problem but using just as effective but much simpler engineering, sounds like B&M.