F-Series FlatYoke™ Valve Actuators

FS and FD Series

  • Ductile Iron & 316 Stainless Steel constructions
  • Flat YokeTM mechanism
  • Weight balanced
  • Torques currently to 80,000”# – Higher torques in process
  • Single & double acting
  • 90 degree rotation + 5 each end
  • Pressures to 120 psig dependent on size
  • Temperatures from –60F to +400F
  • Cycle times as fast as 0.2 seconds

Designed to Outperform

  • Weight and force balanced
  • Fewer seals yield fewer failures
  • Reduced friction for extreme longevity
  • Offset cylinders reduce internal stresses
  • Captured springs for safety
  • Action reversal by turning top side down
  • Outstanding throttling capabilities with optional throttling certification available
  • Exceptional corrosion resistance with stainless steel construction
  • Handles vibrating pipes with ease

Lower Installed Cost

  • Easily lifted into place
  • No bracing required
  • Non-proprietary commodity seals
  • Piston seals replaceable while actuator remains installed
  • Contaminant damaged seals quickly replaceable in line using inexpensive commodity seals
  • Reversible SR cylinders serve as spares if damaged
  • Seal replacement does not require accessory recalibration
  • SR version uses less air volume than most competitors saving $

Numerous Options

  • Partial stroke
  • Dribble control
  • Anti-water hammer
  • High speed / low speed
  • Flexible mounting capability
  • Manual override



Design Overview


A unique slotted body concept absorbs 100% of the yoke mechanism’s side loading forces leaving the piston rod completely free of bending stresses while allowing termination of the rod at the yoke and the addition of a weight and force balancing second force module located diagonally from the first.  Weight balance provides easier lifting and handling of the actuators but also reduces valve neck stress caused by highly unbalanced scotch yoke actuators.  Internally, the balanced forces assure less friction loss and less wear as there is no net force applied to the shaft bushings.

Perfect Weight Balance:  Rather than in-line pistons and springs mounted offset from the shaft axis, but on opposite ends of the body as with typical scotch yoke actuators, the QTRCO FlatYoke™ design duplicated the piston and spring force modules on diametrically opposite ends of the body. This balances the weight as well as the forces acting on the output shaft, eliminating shaft bushing friction, wear and torque absorption. This is made possible by the patented slotted body and roller design.

Flat Yoke® Means Higher Torque

Rack and Gear® mechanisms are limited in torque output by the cost to produce larger and larger gears.  For many years we wanted to expand our torque output range but our business philosophy wouldn’t allow us to make yet another scotch yoke actuator or bring in a copy from offshore.  We needed a new design that would surpass any standard scotch yoke design and provide more benefits to the user.  Finally we found our solution and patented our new Flat Yoke® design.  While providing all of the benefits from our Rack & Gear® design, the low friction Flat Yoke® employs a balanced yoke to economically provide substantially higher torque output.  The decades old scotch yoke design now has a serious challenger.  A smaller, lighter and balanced Flat Yoke® actuator will change the way you think about valve actuation.



All QTRCO actuators use readily available commodity seals.  We do not hide behind proprietary curtains but will tell you the actual part numbers.  But since we have so few dynamic seals and since they fail so infrequently, for three years we will provide free replacement parts, or any other actuator part, regardless of the number of cycles put on them.  See our Warranty page for full details.


Compressed air is like a spring.  And the bigger the air chamber, the bigger the spring.  So when you are pre-filling an actuator and the valve starts to move, a big pre-fill will make the valve appear to ‘jump’ or bounce open, like hopping on an air pillow.  Notice how the springs push the piston towards the end cap?  That tiny bit of space created by the travel stop adjustment is the only pneumatic pre-fill required before the actuator begins moving the valve.  So in addition to consuming less air to operate, Low Fill Volumes also help eliminate valve ‘jump’.


Canted Yokes are now OBSOLETE
GONE are the days of special ordering a Canted Yoke in your actuator.  The longer yoke arms of the Flat Yoke® design allow the advantages of a canted yoke torque curve by simply choosing a different travel stop setting.  This provides substantially more spring end torque without having to up-size the actuator. 


Ease of maintenance is difficult to discuss because it infers that you may actually need to maintain a QTRCO actuator, which is unlikely.  The most likely scenario comes from damage to the piston seals due to contaminants in the air lines.  So, if you have perfectly clean air lines, this section is not for you.  For the rest of the world, here’s the neat fact:  You don’t have to take the actuator off the valve to replace the piston seal.  In ALL QTRCO actuators, regular hand tools can be used to remove the cylinder and end cap, replace the seal, re-lube and replace the cylinder and get back in business.  Yes, it’s that easy.

It’s as easy as turning the actuator upside down!

Both sides of all QTRCO actuators have exactly the same mounting dimensions.  Unlike other actuators that require disassemble of the entire actuator to change from Fail Closed to Fail Open, QTRCO actuators need only be turned upside down to reverse the action.  The Q-Series actuators have a female double-square drive and the F-Series have two keyways located 90-degrees apart to readily accommodate action reversal.