Patent ID: 7387080

Claim:
A pneumatic actuator movement indicator for use with a pneumatic actuator and a source of pressurized fluid for said actuator, the pneumatic actuator movement indicator comprising: a housing adapted to be connected in series between the pneumatic actuator and the source of pressurized fluid, said housing including a first end chamber for placing the housing in fluid communication with said actuator at a pressure P 1 , and a second end chamber for placing the housing in fluid communication with said source of pressurized fluid at a pressure P 2 ; wherein movement of the pneumatic actuator produces a difference between pressures P 1 and P 2 ; and in response to said produced pressure difference, the indicator moves away from said equilibrium position, thereby indicating said movement of the pneumatic actuator; and further comprising a biasing source for applying forces to the indicator urging said indicator back into the equilibrium position after the indicator has moved away from said equilibrium position; and wherein said biasing source includes: a first source secured to the housing on a first side of the indicator and applying a force to the indicator urging said indicator away from the first end chamber of the housing; and a second source secured to the housing on a second side of the indicator and applying a force to the indicator urging said indicator away from the second end chamber of the housing.