Scotch yoke actuator

Design types: Scotch yoke, rack & pinion, Flat Yoke®, Rack & gear®, linear, compact
Supply: air, Nitrogen, gas, typically 3-12 barg
Action: single or double acting
Fail position: fail open, close or in place.
Materials: Carbon Steel, Stainless Steel, Amalga, Aluminum
Manual operation: jackscrew, hand pump

Ledeen

Quarter turn (VA, GS, SY) & Linear (LP)actuator for on/off or modulating control of any ball, plug, butterfly, gate or rising stem ball valve operated by air, natural gas or nitrogen.
Single or double acting, 3-12 bar supply pressure, -30/100°C
VA : 1.100 Nm
GS&SY : 644.000 Nm
LP : 19.752.175 N

QTRCO: Instal it and forget it

The founder of QTRCO, Ed Holtgraver, was responsible for field service of a large valve company. He saw customers lose vast amounts of time, production hours and ultimately money from misapplied products. Products that would have worked better had greater attention to detail been applied during the design phase. By founding QTRCO, Ed’s intent was to design and build actuators that simply did not encounter field service issues. With a very rugged mechanical design and the elimination of normal failure modes—sliding parts, side load forces and numerous seals—the QTRCO actuators have evolved into exactly what Ed had in mind those many years ago.

Used and/or approved by GE, Shell, Akzo, Baker Hughes, Basf, Bayer, DuPont, Exxon, UOP, Invista, LyondellBasel, PPG, Total.

If your regular pneumatic actuator doesn’t last because of extreme conditions QTRCO has the solution and they back this by a 3-year warranty which is independent of the number of cycles.
If you need a closing time as low as 0,1 seconds
If you need high reliability & maximum availability
If your actuator is exposed extreme environmental conditions (corrosive,
high- or low temperatures)
If you require superior control capability (low hysteresis and dead band)
If you require a unique solution for partial stroke, manual override & integrated lockout)

Industries served: food & beverage, (petro)chemical, power, oil & gas, pulp & paper, nuclear and more.

Available material (combinations): Ductile Iron, Carbon Steel, Stainless Steel, Amalga composite.

Reliability by design:

Zero side loading on the shaft bushings
Pressure balanced shaft eliminates thrust force
Massive shaft bushings
Zero cantilever forces

Quarter run

Q series Rack & gear® SA: 847 Nm, DA: 2.374 Nm
T series Rack & gear® SA: 847 Nm, DA: 2.374 Nm
F series Flat Yoke ® SA/DA: 56.500 Nm
Linear
L series 200.170 N

Temperature -60°C to 204 °C

One quarter turn actuator that is fail close and fail open just by turning it upside down

Suitable for (environmental) extremes:

the basis: robust design & premium materials
high and low temperature construction options
high speed stroking capabilities
standard design suitable for high cycle applications
complete SS construction available

Customers have reported over 15.000.000 cycles without failure.

Maximum availability with low cost of ownership

If necessary, seal replacement can be done while the actuator is on the valve
Dual travel stops eliminate the need to recalibrate the switches or positioner.
Spring return actuator cylinders can be turned while the actuator is on the valve, a new sealing surface is provided with the “inherent” on board spare part.
Non-proprietary actuator seals are readily available. This is the only seal in the actuator.
Captured springs located inward of the pistons allow fast and easy maintenance.

Temperature capabilities

Ultra low -60 / 85°C
Low -50 / 85°C
Standard -29 / 85°C
High -29 / 200°C
Limits may be extended with proper insulation

Superior control capability

Take away the lag and drag so you know when the actuator and valve start and stop:
minimal friction by design, less hysteresis & variability
tighter tolerances to reduce backlash & hysteresis
elimination of side loading force
tighter tolerances for valve to actuator connection to reduce dead band.

Actuator design that resolves every issue with currently available partial stroke testing solutions.

Scotch yoke design	Effect	Flat yoke® solution
Long & heavy spring on one end, small and light piston on the other	Imbalanced weight with SR, stress on the valve “neck” and piping & possible mounting & space issues.	Balanced weight design: less space & weight, no stress on the valve and piping.
Single yoke arm design	Imbalanced internal forces: wear & torque reducing friction	Balanced force design: zero side loading
Piston pressurized on body side	Piston rod seals required	Design without rod seals
Proprietary rod seals	Expensive, not readily available	Design without rod seals
Piston rod seals wear	Complete actuator disassembly when replacement is required	Design without rod seals
Piston rod self supporting or support structure in body	Side loading on piston rod	Design where side loading is absorbed in body, non applied to the rod.
Fail action reversal requires parts to be placed at opposite side	Actuator needs to be disassembled by trained personnel in the workshop	Design where actuator only needs to be turned upside down
Travel stops are on yoke arm	Piston and spring forces continuously to act with maximum values on yoke arm.	The inward and outward piston motion is stopped directly by using aligned travel stops

Rack & pinion design	Effect	Rack & Gear® solution
Piston axis align to cylinder bore	Exhibit high friction % wear from internal cantilever-initiated forces	Offset cylinders so that piston axis align with gear PCD. No damaging forces
Outward forces push rack against the cylinder wall	Creating friction & motion resistance as rack slides against the cylinder	Eliminate contact between rack & cylinder. No contact no friction.
Shaft seals are pressurized every cycle	Seals will wear, complete disassembly required to replace	Move springs inward of cylinders. Pressurize SR actuators between piston & end cap. Non pressurized seals don’t leak.
Bottom end of shaft bigger than upper: shaft pushed down	Additional friction & wear	Balanced shaft: no up or down forces
Shaft & mounting geometry are different on top and bottom side of the actuator	Disassembly required to reverse actuator action	Top & bottom are identical. Just turn the actuator to change fail action. No disassembly required.
Complete disassembly required for maintenance	Removal from valve required	Standard possible to replace piston (only) seals with actuator on the valve.
Cylinders are an integral part of the actuator body	If cylinders are damaged the complete actuator needs to be replaced	Cylinders are a separate component to enable replacement. With SR actuators cylinders can be turned in the field (inherent spare part)
Not all springs are captured	Safety can be an issue during service	All springs are captured. Safety is improved.
Sometimes the travel stop only contacts 1 piston or a single cam is used.	Travel stops create side loading, friction & shaft wear	Both pistons are stopped simultaneously: zero side loading

Ledeen

QTRCO: Instal it and forget it

Reliability by design:

Quarter run

Suitable for (environmental) extremes:

Maximum availability with low cost of ownership

Temperature capabilities

Superior control capability

Documentation

Documentation QTRCO

Documentation Ledeen

Need to let it flow? Call on Wegman!

Need to let it Flow? Call on Wegman!