Scotch Yoke Actuators

A Scotch yoke is a mechanism commonly used in mechanical engineering to convert rotary motion into linear motion. Scotch yoke mechanisms are often employed to achieve reciprocating linear motion. A Scotch yoke actuator consists of a circular disk (cam) mounted on the rotary output shaft of a motor. Connected to the disk is a sliding block, or yoke, which is guided along a linear path. As the motor rotates the cam, the yoke undergoes a reciprocating motion.

Actreg Scotch Yoke Actuators

Actreg Scotch Yoke Actuators are intricately designed to deliver extended and efficient functionality while demanding minimal maintenance. Enhancing the durability of Actreg Scotch Yoke series actuators is the incorporation of a totally enclosed weatherproof center-body and caps. This robust design is fortified with O-rings to provide robust water ingress protection, safeguarding the internal components from adverse environmental conditions.

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Air Torque Scotch Yoke Actuators

The Air Torque Heavy Duty Scotch Yolk Actuator Series stands as a pinnacle in the industrial automation industry, manufactured for both on/off and modulating duties. This series, renowned for its robust design and versatile functionality, caters to a spectrum of applications by seamlessly operating ball valves, butterfly valves, and plug valves.

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Rotork Scotch Yoke Actuators

Rotork's GP (pneumatic) and GH (hydraulic) range scotch yoke actuators are meticulously engineered to deliver efficient rotary, quarter-turn movements, making them ideal for both on/off and modulating duty applications. The actuators feature a robust yet space-efficient design, providing reliability in various industrial settings. These actuators feature two distinct yoke designs to cater to diverse operational needs. The classic symmetric yoke is characterised by its ability to generate peak torque at both ends of the stroke, ensuring a well-balanced performance.

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Frequently Asked Questions

Scotch Yoke Actuators are mechanical devices that convert linear motion into rotary motion, commonly used for quarter-turn valve control.

These actuators utilise a yoke mechanism to translate linear motion into rotary motion, providing the necessary force to operate valves.

Scotch Yoke Actuators are often employed in industrial settings for on/off or modulating control of valves in processes such as oil and gas, water treatment, and power generation.

The symmetric yoke design ensures peak torque at both ends of the stroke, providing a well-balanced and reliable performance.

The canted torque arm design delivers peak torque at only one end of the stroke, potentially reducing actuator size, weight, and cost for specific valve applications.

Yes, Scotch Yoke Actuators are available in both GP (pneumatic) and GH (hydraulic) variants to accommodate different system requirements.

Factors include torque requirements, operating conditions, valve size, and the duty cycle of the application.

Yes, these actuators can be designed to handle high-pressure environments, especially in hydraulic applications.

Some models can be designed to meet explosion-proof or hazardous area certifications for safe operation in such environments.

Maintenance requirements typically include lubrication, periodic inspections, and, if needed, replacement of wearing parts.

The size is determined based on the torque requirements of the valve, taking into account factors such as pressure and temperature.

In many cases, yes. However, it's crucial to ensure compatibility and proper sizing during the retrofitting process.

FAQ

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Scotch Yoke Actuators

Brief Specifications:

Function:Spring Return, Double Acting
Body Material:Corrosion Protected Carbon Steel
Rotation:90°
Torque Levels:60,000 NM
Temperatures:-40°C to +320°C
Operating Media:Dry/Lubricated Air, Inert/Non-Corrosive Gases, Hydraulic
Pressure Rating:Max 10 Bar-Pneumatic (145 PSI) Max 210 Bar-Hydraulic (3045 PSI)
Certifications:ISO 9001

Pneumatic Scotch Yoke Actuators are designed to operate in the harshest, most demanding industrial applications and environments where functionality and reliability are required throughout the complete cycle of valve automation. Predominantly used for larger sized Ball & Butterfly Valves the Scotch Yoke Actuator offers 90° quarter turn, on-off operation by converting linear movement to rotary action through the internal driving cylinder and scotch yoke mechanism with high start and end torque output up to 60,000NM.  This, in turn, transmits power continuously and precisely to perform the operation of the Ball or Butterfly Vale. The ATHD Air Torque Scotch Yoke Actuator is a compact, lightweight and economical unit bringing reliability and low maintenance to industries where it is needed most and offering long, uninterrupted service. Available in both Spring Return & Double Acting units setup can be arranged in either the fail-safe open or closed positions, returning the actuator and valve position to the required safety location in the event of a power failure.

Double Acting Scotch Yoke Actuators:

In the example below, air supplied at port 2 is released into the chamber and forces the piston towards the central module of the scotch yoke actuator, in turn performing the counterclockwise rotation through the scotch yoke mechanism and opening of the connected valve. Exhaust air is exited through port 4. To perform the closing operation air is supplied through port 4 from the central module of the actuator. Forcing the piston to the end of the body chamber and clockwise rotation is achieved. Exhaust air is exited through port 2.

Spring Return Scotch Yoke Actuators:

For Spring Return Scotch Yoke Actuators, air supplied at port 2 is released into the chamber and forces the piston towards the central module of the actuator, this compresses the spring in the opposite chamber and performs the counterclockwise rotational movement, opening the valve. Exhaust air is exited through port 4. Depressurisation to port 2 through the use of an intentional or non-intentional action allows the spring to move the piston back towards the opposite end of the air chamber and immediately closes the valve. Exhaust air is exited through port 2.

Features And Benefits Of Pneumatic Scotch Yoke Actuators:

Pneumatic Scotch Yoke Actuators offer many features and benefits for the operational actuation of ball, butterfly and plug valves.

  • A compact, lightweight, economical and reliable design provides long-lasting effective service.
  • Higher breakout torque from zero position makes this actuator the perfect solution for soft seated ball and butterfly valves where 75% of the torque is generated by the seat.
  • Increased torque for spring return position.
  • Fail safe open or close setup available.
  • Emergency manual override features including jack screw, hand pump and gear operation.