Heedm, a very interesting answer.... .. .You are correct, cohesion of the material of the drum, does create a force to cause the drum to "push" against the pads to create the necessary friction to cause the clutch to transfer power. However, this clutch design (like many different clutch designs) operates by pressure creating friction between 2 or more surfaces.. .. .You've accurately described how the clutch drum applies pressure to the pads to create the necessary friction for this design, but my question deals specifically with how the pads apply pressure to the clutch drum to create the necessary friction. These two surfaces MUST apply pressure against each other to create the power transfering friction, so specifically, what force is causing the pads to apply pressure to the clutch drum?