Manufacturer
Scotch Yoke Actuator Manufacturer
High-torque scotch yoke pneumatic actuators from a Wenzhou factory: AW-series units from 100 Nm to 200,000+ Nm with increased torque at the valve end positions, ductile iron bodies for heavy service, and sizing support for large quarter-turn valves up to DN1200.
Why Buy Direct
Torque Where the Valve Needs It Most
Scotch yoke actuators are a different machine from compact rack and pinion units: larger frames, higher torque, and a torque curve shaped to the physics of big valves. The AW series is engineered for that duty, and the sections below cover construction, testing and the applications that justify the specification.
Yoke Mechanism, End-Position Torque
A scotch yoke converts linear piston travel into rotary output through a sliding yoke and pin, and the geometry does something useful: torque rises toward the 0° and 90° end positions, where valve seating and unseating demand the highest force. The AW series is engineered around this torque profile, so a large butterfly or ball valve gets its breakout torque exactly when the disc or ball is leaving the seat, with lower torque through mid-travel where the valve needs less. The ratio between piston stroke and output rotation is chosen per frame so the actuator's torque curve tracks the valve requirement through the full 90°, which is why a scotch yoke unit can often be a frame size smaller than a rack and pinion for the same valve duty.
Heavy-Service Construction
Big valves mean big forces, and the AW series is built accordingly. Bodies are cast ductile iron or carbon steel, yoke slides are available in single and double slide configurations, and the whole assembly is designed for low air consumption per cycle so large units stay economical to run. Piston and yoke slides run on replaceable wear surfaces, and the cylinder bores are machined and honed in-house, which keeps rebuild costs predictable when units eventually need service after years of cycling. This construction suits continuous plant duty in oil and gas terminals, power stations and water treatment works, where downtime for actuator repair is measured in lost production.
Project-Level Sizing & OEM Support
High-torque actuators are rarely bought off a price list — they are sized against a valve torque curve. Our engineers take your valve type, size, pressure class and operating differential, add an application safety margin, and recommend a frame with the correct supply pressure and fail-safe requirement. ATEX-specified versions are available for hazardous areas, and OEM customers can have their own brand, nameplate and documentation fitted to the same frames. For EPC and valve package buyers, we provide sizing documents, installation drawings and the torque data needed for control valve assemblies, so the actuator arrives as part of a documented package rather than a loose component.
Product Line
AW Series Scotch Yoke Range
| Parameter | AW Series Specification |
|---|---|
| Output Torque | 100 – 200,000+ Nm |
| Torque Profile | High at 0° and 90° end positions (breakout) |
| Rotation Angle | 90° |
| Supply Pressure | 3 – 10 bar |
| Operating Temperature | −20°C to +120°C |
| Body Material | Cast ductile iron / carbon steel |
| Yoke Type | Single slide / double slide |
| Typical Valve Sizes | DN200 – DN1200, depending on pressure class |
* Torque and valve size figures are reference values; final selection is made against the valve torque curve and application safety margin. ATEX versions available for hazardous area service.
Quality & Testing
Breakout Torque Verified, Not Assumed
A scotch yoke actuator is only as good as its torque at the seats, so the test station for AW-series units is built around end-position measurement. Each unit is stroked on a calibrated torque rig and output is recorded at the 0° and 90° positions as well as through mid-travel, then compared with the datasheet curve for the customer's supply pressure. Air leak tests at rated pressure confirm piston and yoke seals, and full-stroke cycling checks smooth travel and the travel stop function.
For heavy-service frames, batch samples also undergo endurance cycling while torque and leak rate are monitored, and material certificates for the ductile iron and carbon steel bodies are provided with the documentation pack. ISO 5211 mounting faces are dimensionally inspected on every unit, and per-lot QC reports are issued with each shipment so the evidence follows the goods.
Field experience on large valves is also fed back into the build: seal material, yoke slide finish and fastener torques are reviewed against service reports, and any change is validated on the endurance rig before it goes into production. That feedback loop is one of the advantages of manufacturing the units in-house rather than importing finished product, and it shows up in the detail items that extend service life on demanding installations.
What We Test
- ✓End-position torque measurement at 0° and 90°
- ✓Mid-travel torque curve check against datasheet
- ✓Air leak test at rated supply pressure
- ✓Full-stroke cycle check and travel stop verification
- ✓ISO 5211 dimensional inspection of mounting faces
- ✓Material certificates for ductile iron / carbon steel bodies
Applications
High-Torque Applications We Supply
Scotch yoke actuators earn their place wherever a large quarter-turn valve must break out of its seat reliably, cycle after cycle, in continuous or safety-critical service.
FAQ
Scotch Yoke Actuator Manufacturer — FAQ
Why choose scotch yoke for large valves?
The yoke geometry delivers more torque at the end of travel, exactly where large valves demand the highest force for seating and unseating. For valves above roughly DN200, or where the pressure differential creates high breakout torque, a scotch yoke actuator usually provides the required output in a smaller, more economical package than an oversized rack and pinion.
What is the largest scotch yoke actuator you make?
The AW series covers output torque up to 200,000+ Nm, which suits quarter-turn valves up to about DN1200 depending on pressure class and the valve torque curve. Send us your valve details and operating conditions and we will confirm the frame size and configuration.
Do you supply ATEX-certified scotch yoke actuators?
Yes. ATEX-specified versions are available for oil & gas and other hazardous area applications, with certification documents supplied with each unit. Indicate the required zone and gas group when requesting a quotation so the correct specification is quoted.
Can scotch yoke actuators be spring return for fail-safe duty?
Yes. AW-series scotch yoke actuators are available in spring return configuration for fail-safe open or closed operation on large valves. Spring torque is sized against the valve seating requirement and can be pre-loaded to match, so safety-critical lines keep their fail position even with large valve masses.
Sizing Support for Large Valves
Valve type, size, pressure class and fail-safe position — our engineers return a scotch yoke frame recommendation and factory-direct pricing within 24 hours.