A frictional resistance coupling comprises an outer part and an inner part, which are connected to each other in a pressure-tight manner and between them form an inner chamber with a conical surface and a likewise conical, axially displaceable annular piston. The annular piston is moved axially due to the supply of pressure medium, for producing a radial tension and frictional resistance between two parts, e.g., a coupling and a shaft. Serving for determining the axial position of the enclosed annular piston is an axially disposed transmitter cylinder, which is connected to a receiver cylinder in the region of the outer surface of the coupling, by way of an incompressible medium. The piston of the receiver cylinder supports an indicator, whereof the position is monitored by an external sensor. The transmitter cylinder and receiver cylinder form a hydraulic linkage, preferably with displacement translation for monitoring even small piston movements with reliable control of whether the annular piston has reached its end position. For this purpose, the sensor monitors the position of the indicator attached to the receiver piston, on the outer periphery of the coupling.