Design of a short polarization converter on InP/InGaAsP using asymmetrical waveguides

A brake actuator having a stone shield located within the brake actuator housing and surrounding the brake actuator piston which dampens the impact of the brake actuator piston against the end wall surrounding the end wall opening. The damping stone shield includes an annular body portion having a diameter less than the brake actuator end wall opening and opening which receives the reciprocal piston of the brake actuator and an integral radial flange which overlies the inner surface of the brake actuator end wall opening. The annular body portion of the stone shield includes a first end portion extending at least partially through the brake actuator end wall opening having an annular groove surrounding the piston and damping the impact of the piston against the end wall surrounding the end wall opening. In the preferred embodiment, the annular groove extends through the first end portion of the stone shield and is bell-shaped or tapered in cross-section having a rounded end surface. The opening through the body portion is preferably hyperbolic having openings at the first and second end portions greater than the mid portion and the second end portion is spaced from the radial flange preferably having a diameter less than the first end portion.