Low Pressure Quarter-Turn Actuators

Product Details

The ATI Scotch Yoke M-Series Actuator is designed for use with both hydraulic and pneumatic power to operate a quarter-turn valve.

Controls may include both local and remote control with selector switches. The control systems may be designed for hazardous areas up to Class 1 Division 1/Zone 1 or Zone 1 with certified electrical components.

This system is capable of providing precise quarter-turn valve control for ON/OFF and modulating valve applications.

Low Pressure Quarter-Turn Actuator photo

Low Pressure Quarter-Turn Actuators

ATI Scotch Yoke Actuators are suitable for many quarter-turn applications including ball, plug, butterfly valves, or dampers, in both On-Off and modulating heavy-duty service.

The Scotch Yoke unit works in the following general way:

• For a double-acting configuration, pressure is supplied to the pressure port on either the inside or outside end cap of the power module which will rotate the yoke/valve stem up to 100°.

• For a spring-return configuration pressure is supplied to the outside end of the power module which will rotate the yoke as it compresses the spring of the spring module.

• The actuator stroke of the yoke is adjustable between 90° and 100° by means of the external mechanical stops screwed into the body of the actuator.

• The cover of the scotch yoke mechanism is arranged for the assembly of the required accessories (positioner, signaling limit switches, position transducer, etc.) by means of proper matching units. The above-mentioned accessories are operated by the yoke indicator plate.

• The housing of the scotch yoke mechanism is machined with a threaded hole flange pattern to fix the actuator to the valve directly or, if required, with an adapter flange or mounting bracket.

• The actuator yoke has a bore with keyways suitable for the dimensions of a valve stem or a drive slot suitable for a coupling device.

• ATI may supply different types of control systems following customers’ requirements.

Product Highlights

Operating Pressure.

The working pressure range for a standard ATI Scotch Yoke Power Cylinder is as follows:


– MINIMUM: 500 psig (34.5 bar)

– STANDARD MAXIMUM (SMAWP): 1,500 psig (103.4 bar)


– MINIMUM: 50 psig (3.45 bar)

– STANDARD MAXIMUM (SMAWP): 150 psig (10.24 bar)

The minimum pressure may be lower than 500 psig and 50 psig, for hydraulic and pneumatic cylinders, respectively, due to backpressure in control circuits. For use with Higher or Lower pressures consult with ATI Representative.

NOTE: The maximum pressure is in reference to just the power modules. When assembled onto the body module the maximum pressure for the system may decrease. Please reference DS1002 Scotch Yoke Torque Table Data for maximum pressures for specific actuator models.

Temperature Limits

Operating Temperature

System Operating Temperature*
standard  -40℉ to +212℉ (-40℃ to +100℃)

*For temperatures outside standard consult with an ATI Representative.

Duty Cycle & Cycle Speed

The Product is capable of intermittent duty and continuous duty when operated within recommended temperature limits with properly filtered fluid. The stroke speed is controlled by the control circuit for fluid supply and typically varies between 5 seconds to 60 seconds.

For required speeds outside the range, please consult with an ATI Representative

Fluid Type

The Product is designed and constructed of heavy-duty materials for operation in systems using petroleum-based fluids for hydraulic power. Pneumatic operation is designed for filtered nitrogen and compressed air.

For use with other fluid types please consult with an ATI Representative.

Service Life

ATI Scotch Yoke Systems can be operated with petroleum-based hydraulic fluids or filtered pneumatic fluid for up to 5 years without maintenance. In harsh environments and safety-critical applications, more frequent maintenance intervals and a proper fluid monitoring program should be considered to ensure reliable Product performance.

With regular maintenance and monitoring of the fluid, the service life for this actuator will extend well beyond 5 years.


For normal duty, the actuator is self-lubricated for the life of the Product.
The hydraulic fluid should be filtered and monitored for cleanliness to a contamination threshold of 20/18/15 per ISO 4406 (NAS 9). Lower contamination thresholds are recommended to maximize service life.

Lifting Point Load Ratings

Use lifting straps or chains rated for a minimum of 2000 lbs.

Pressure Connections

Per assembly drawing:
Hydraulic and Pneumatic connections will be located on the outside and inside end caps of the power module. The size of the connection will vary based on the Scotch Yoke Model size and can be viewed in data sheet DS1001 Scotch Yoke M-Series Dimensional Data.

Torque Ratings for each SYM model.

Model Torque Capacity (in*lbf)
SYM1 80,000
SYM2 190,000
SYM3 375,000
SYM4 750,000
SYM5 1,250,000

Torque Rating is based on a springless Double-Acting actuator. For specific spring return torque capacities please refer to DS1002 SYM Torque Table Data or consult with an ATI Representative.


Complete warranty terms and conditions are included in the product manual.

ATI Scotch Yoke Systems, if handled, installed, used, and maintained according to this manual, are guaranteed to be without defects in material and workmanship. The warranty period is two (2) years after the date of factory shipment. Refer to the Product nameplate for the serial number to confirm the date of shipment. The warranty does not cover accessory components installed by others or materials that are installed inappropriately, used inappropriately, or modified or repaired without approval by ATI.

NON-WARRANTY CLAUSE: Contents of this publication are periodically checked for compliance with the associated Products, and corrections are made as necessary for subsequent publications. ATI also modifies the Product in this publication (within the limits of Optional Certifications) to meet special requirements for specific customer orders. Therefore, ATI cannot exclude the possibility of discrepancies between this publication and the Product and special documentation that is prepared for a particular shipment, and ATI does not accept liability for discrepancies between information in this publication and the Product.


ATI Low Pressure Quarter-Turn Actuators are used in the following industries. Click below to learn more.

Oil & Gas | Power | Chemical | Mining | Pulp & Paper | Water


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