Torque Transmission : The clutch should be able to transmit the maximum torque of the engine under all conditions. It is usually designed to transmit 125 to 150 percent of the maximum engine torque. As the clutch slips during engagement, the clutch facing is heated. Clutch temperature is the major factor limiting the capacity of a clutch. This requires that the clutch facing must maintain a reasonable coefficient of friction with the mating surfaces under all working conditions. Moreover, the friction material should not crush at high temperatures and clamping loads.