Cam actuated anti-lock braking system modulator

An anti-lock braking system (ABS) pressure modulator for a braking system having a wheel cylinder and a master cylinder, the pressure modulator having connections for the wheel cylinder and the master cylinder, the pressure modulator comprising:

• a frame having a bore fluidly exposed to the master cylinder and wheel cylinder connections and a check valve means for preventing fluid communication from the master cylinder connection to the wheel cylinder connection via said bore, said bore having a longitudinal axis;
• a piston slidably sealably mounted within said bore for reciprocal movement along said longitudinal axis for providing a variable control volume in communication with the wheel cylinder and thereby modulating the pressure therein, said piston having means for opening said check valve means when said piston is at a predetermined extreme position, said piston having a cam follower surface;
• power means;
• and
• a cam moved by said power means having a cam surface in contact with said cam follower surface of said piston whereby movement of said cam in a first rotational direction moves said piston toward said predetermined extreme position and the subsequent movement of said cam in a second rotational direction, opposite to said first rotational direction, allows said piston to move away from said predetermined extreme position, characterized in that
• said cam follower surface is in the form of a roller operatively associated with said piston, and a one-way brake means is operatively connected to said roller for preventing rotation of said roller when said cam moves in said second rotational direction, but allowing said roller to roll over said cam surface when said cam moves in said first rotational direction.