A master cylinder for use in the power train of a motor vehicle to actuate the brakes or the friction clutch is designed to avoid the generation of screeching noise and/or the transmission of stray movements to the piston rod in response to shifting of the piston relative to the housing and relative to the sealing element(s) between the piston and the housing. This can be accomplished by causing the piston to turn relative to the housing and the sealing element(s) during axial movement in the housing and/or by installing one or more dampers between the piston and the housing and/or between the piston and the piston rod. The dampers can constitute separately produced parts and/or specially configured and/or finished surfaces provided on the piston and contacting the housing and/or the sealing element(s). The invention also relates to improvements in the configuration and/or the material(s) of the piston.