(1) The belt slips on the pulley and cannot transmit power.
(2) The belt is delamination, tearing and tensile due to fatigue.
(3) The working surface of the belt is worn.
(4) Torsional vibration of driven shaft.
Ensuring that the belt does not slip in the work, and has a certain fatigue strength and service life is the main basis for the design of the V-belt, and it is also the main basis for the design of other belt drives driven by friction.