An auxiliary device of a friction
clutch is characterized in that a working cylinder is in a disc shape, an input shaft is fixedly connected with the cylinder, an output shaft is installed in a through hole of a shell through a bearing,
magnetorheological fluid is arranged in a cavity of the cylinder, the
viscosity coefficient of
magnetorheological fluid is influenced by the magnitude of current of a coil, and therefore the magnitude of loads loaded on a driven disc of the
clutch is influenced, and the aim of making connection of the
clutch smoother is achieved. A
magnet exciting coil is fixed to an outer
magnetic core which surrounds the outer side of the cylinder, and therefore the
magnetic field distribution can be improved, and the auxiliary device works more stably; if the
magnet exciting coil is damaged, the
magnet exciting coil can be easily replaced, and therefore use performance of the auxiliary device is improved. Due to the fact that the
controllability of
magnetorheological fluid is high, the auxiliary device rapidly responds to the clutch. After the friction clutch is fully connected, a slide block overcomes the tensile force of a reset spring and is inserted into a machined groove in the cylinder, the output shaft is in rigid connection with the cylinder, the
electromagnetic coil can be powered off at the moment, the rigid connection of a
transmission system is kept, the auxiliary device does not need to be powered for a long time through the
electromagnetic coil, and the
high transmission efficiency and high stability of the
transmission system are ensured.