The Fisher 657-40 actuator is a direct-acting, spring-opposed diaphragm actuator designed for precise control of valve plug positioning in response to pneumatic signals. It is part of the Fisher 657 series, which includes multiple sizes and configurations for versatile industrial applications.

• Type: Direct-acting diaphragm actuator
• Size: 40 (part of the 657NS series which includes sizes 40, 45, 70, and 80)
• Action: Spring-opposed; actuator positions the valve plug based on pneumatic input
• Spring Range: Adjustable via spring compression and selection of spring rate
• Travel Stops: Available for precise control and safety
• Manual Operators: Optional for manual override in control systems
• Mounting: Compatible with both direct-acting (push-down-to-close) and reverse-acting (push-down-to-open) valve configurations
• Loading Connection: Pneumatic signal applied to diaphragm to actuate movement
• Applications: Suitable for on-off or throttling operations in automatic control valves