Rocker arm with outwardly sprung hydraulic actuator piston

A rocker arm for conveying valve actuation motions, the rocker arm comprising a motion receiving portion configured to receive the valve actuation motions from a valve actuation motion source and a motion imparting portion configured to convey the valve actuation motions to a valve train component or at least one engine valve, the rocker arm further comprising:

• a hydraulic actuator piston slidably disposed in an actuator bore;
• and
• an actuator spring configured to bias the hydraulic actuator piston out of actuator bore and into contact with the valve train component or the at least one engine valve, wherein reaction of the hydraulic actuator piston against the valve train component or the at least one engine valve biases the motion receiving portion of the rocker arm into contact with the valve actuation motion source,
• wherein, in an unactuated state of the hydraulic actuator piston, hydraulic fluid is permitted to flow out of the actuator bore and, in an actuated state of the hydraulic actuator piston, hydraulic fluid is locked in the actuator bore.