Scotch Yoke Actuators
We manufacture a range of scotch yoke quarter turn actuators, which give torque outputs from 4,000 to 54,000 lb. ft. These actuators can be operated by instrument air, hydraulic fluid or line gas. Remote and local control can also be provided, and a hydraulic hand pump is available for emergency operation.
Scotch yoke mechanism
At the heart of Cort actuators is a ruggedly constructed scotch yoke mechanism. Its purpose is to convert the linear motion of the driving cylinder to the rotary motion required to operate the valve. This is achieved by the piston rod driving phosphor bronze blocks, which slide between the arms of a pair of slotted levers welded to the stem drive sleeve. The side thrust generated by the mechanism or the piston rods is contained by a rigid guide bar.
Unlike crank and rack and pinion mechanisms, the scotch yoke produces more torque at the start and end of travel than during its travel. It is therefore ideally suited to operating ball valves, because its torque output closely matches the torque requirement of the valve.
| Scotch yoke ref. | Max. torque output (lb ft) | Max. torque output (Nm) | Midpoint torque output (lb ft) | Midpoint torque output (Nm) | Std. valve flange P.C.D (in) | Std. valve flange P.C.D (mm) | Std. stem diameter (in) | Std. stem diameter (mm) | Typical weight (lb) | Typical weight (Kg) |
|---|---|---|---|---|---|---|---|---|---|---|
| AC01 | 4,000 | 5424 | 2,500 | 3390 | 10.25 | 260.4 | 2.375 | 60.33 | 300 | 136 |
| AC02 | 10,000 | 13,560 | 6,250 | 8,475 | 14 | 355.6 | 2.875 3.5 |
73.03 88.9 |
500 | 227 |
| AC03 | 25,000 | 33,900 | 15,625 | 21,188 | 14 | 355.6 | 3.5 4.75 |
88.9 120.65 |
1200 | 544 |
| AC04 | 40,000 | 54,240 | 25,000 | 33,900 | 14 | 406.4 | 4.75 6 |
120.65 152.4 |
2000 | 907 |
| AC05 | 54,000 | 73,224 | 33,750 | 45,756 | 20 | 508 | 6.5 | 165.1 | 2400 | 1087 |