A pressure supply unit for a brake system including a booster body that defines an axially extending cylinder. A piston is slideable within the cylinder. The piston defines a bore that receives a spindle. The spindle is rotationally fixed and axially moveable for providing the axial movement of the piston. A motor is positioned about the spindle and is configured to axially translate the spindle and piston. A ball and socket joint connects the piston and spindle while accommodating pivoting movement of the spindle. The ball and socket joint includes a ball at a front end of the spindle and a socket in the bore of the piston which receives the ball.