Stroke limiter for hydraulic actuator pistons in compression release engine brakes

Apparatus for limiting the stroke of a piston in a hydraulic actuator cylinder due to introduction of pressurized hydraulic fluid into said cylinder adjacent an end surface of said piston, said end surface being substantially perpendicular to the axis along which said piston moves in response to said pressurized hydraulic fluid, and said end surface having an aperture through which hydraulic fluid can escape from said cylinder when said aperture is opened, said aperture comprising:

• a piston follower member movably mounted in said cylinder between said end surface and an end of said cylinder which faces said end surface, said member being movable relative to said cylinder and said piston substantially parallel to said axis, a first end of said member being disposed adjacent said end surface and being shaped to selectively close said aperture and thereby prevent hydraulic fluid from escaping from said cylinder via said aperture, and a second end of said member which faces away from said first end being shaped to selectively bear on said end of said cylinder and thereby enable said member to act as a stop for stopping motion of said piston toward said end of said cylinder when said end surface contacts said first end and said second end contacts said end of said cylinder;
• and
• a stop structure for limiting the amount by which said member can travel with said piston away from said end of said cylinder so that when said stop structure is operative, said member is prevented from continuing to move away from said end of said cylinder with said piston and said aperture is accordingly opened to release hydraulic fluid from said cylinder and thereby prevent said piston from continuing to move in response to hydraulic fluid pressure in said cylinder.