The pin coupling relies on the locking force of the pin group to generate the frictional moment on the contact surface, and compress the rubber elastic sleeve to transmit the torque. The pin coupling is suitable for small and medium power shafting transmissions with good rigidity of the installation base, high centering accuracy, low impact load, and low requirements for vibration reduction. The two shafts connected by the pin coupling will change the relative position of the two shafts due to manufacturing and installation errors, deformation after load, and temperature changes, and strict alignment is often not guaranteed. The main types and characteristics of pin couplings and their role in the transmission system.