Patent ID: 8261547

Claim:
A pneumatic actuator ( 100 ) comprising an actuator body ( 102 ) and a piston rod ( 108 ) extending from the actuator body ( 102 ), with the piston rod ( 108 ) moving over an actuation span, with the pneumatic actuator ( 100 ) being characterized by: a piston ring ( 110 ) located in an outer shell ( 101 ) and below a piston ( 120 ), with the piston ring ( 110 ) slidably located in the outer shell ( 101 ) and being configured to sealingly slide on the piston rod ( 108 ), wherein port E is located below the piston ring ( 110 ) and the piston ring ( 110 ) moves up and pushes the piston ( 120 ) upward when pressurized gas is introduced into port E; a first stroke span that is traversed by the piston rod ( 108 ) at a first actuation speed; and a second stroke span that is traversed at a second actuation speed that is substantially slower than the first actuation speed.