Product - RTCH Scotch Yoke Hydraulic Actuators
​​​​The RTCH Series is a range of compact hydraulic quarter turn​ actuators with materials selected to withstand the most hostile environmental conditions. They are suitable for all onshore and offshore applications, covering the majority of on-off and modulating alves. The RTCH Series is designed to provide maximum reliability and flexibility to cover a wide range of valves in all pressure classes.

​Key features

  • Double acting or spring return modular design
  • Totally sealed weatherproof housing that provides complete protection for all moving parts
  • Housing is manufactured in carbon steel material without any cast/grey/ductile iron or aluminum parts
  • Scotch yoke mechanism available in both canted or symmetrical exec​​utions
  • Chromium plated guide bar to absorb transversel forces
  • Bushings are made of high strength bronze alloy (oth​​er materials on application)
  • Electroless nickel plated cylinder to minimise friction and prevent corrosion
  • Power module design for safety allows replacement of the cylinder seals without any danger
  • Multiple certified lifting lugs ideally located to balance center of gravity for safe lifting
  • ISO 5211 flange connection
  • Position indicator provided with VDI/VDE 3845 NAMUR drive slot
  • An integral hand-pum​p available on request
  • Full stainless ​​steel version available on request
  • Single gasket for easy maintenance, no external tie rods (spring return version)​​​​​​


ReliableRugged carbon steel housing and high-strength alloy steel scotch yoke with a heavy-duty nickel plated cylinder ensure safe and reliable operation. Ho​using is not put under any pressure, minimising leakage points and simplifying maintenance. For spring return, cylinder seals can be replaced safely without removal of the spring.

The watertight housing is also coated internally to ensure long-lasting corrosion resistance. ​​Stainless steel travel stops allow fine stroke adjustment between 82° and 98°.

Designed to provide high torque with minimum space and weight. Symmetrical or canted scotch yoke for ideal torque distribution. For spring return, the hydraulic cyclinder is installed inside the spring.

For spring return maximum safety is ensured through the spring pack design which allows the spring compression to take place without removing the cylinder cap and screws.​

​Technical specifications

Operating pressure
Up to 350 Bar

Standard supply m
Hydraulic oil (special version for fire resistant fluids on request) 

Standard operating temperature
-30°C to 100°C (high/low temperature design available on request)

Output torque​
From 40 Nm up to 6,000 Nm for double acting version

Spring Ending Torque
From 40 Nm up to 2.500 Nm for single acting version (higher values on request)

Certifications / approvals
PED 2014/68/EU 
ATEX 2014/34/EU
EAC TR TS 012/2011 
IP66/67M according to IEC/EN 60529 
SIL3 (IEC 61508) as a “single device” 
Designed and tested in accordance with 
EN 15714-4
Further certifications are available please contact IMI STI for updated list.​​

Our innovative Zero Backlash mechanism improves performance and solves the wearing-related gap issues between the sliding block and the scotch yoke slot, maintaining friction at similar levels to even the most established technology. It is available on request, please contact us for more information.​

​Product breakdown​​

​Optional accessories

IMI STI designs and produces a wide range of accessories and control systems to ensure superior performance and to satisfy the most emanding requirements in modulating, on/off and heavy duty service. Control systems panels/cabinets can be installed on the actuators or supplied loose for remote mounting which allows for easy access and to limit exposure to excess heat and vibration. For more information, see our dedicated brochure of accessories. ​​​

Latest News

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16 September 2019
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Largest Romanian customer recommends IMI Remosa
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Lean success in IMI Critical back office functions
04 May 2018
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30 April 2018
IMI Critical Korea closes in on world-class LEAN performance
27 April 2018
IMI board tours IMI Critical businesses
25 April 2018
New positioner software tools from IMI STI
08 February 2018
Launch of Zero Backlash Scotch Yoke Mechanism
16 January 2018
IMI Critical Korea certified to sell actuators in Europe
20 September 2017
IMI Critical named ‘supplier of the year’ by Korea’s Doosan
19 September 2017
100th Valve Doctor graduates from IMI Critical
13 September 2017
Top HSE certification for IMI Critical’s California site
12 September 2017
Launch of High Endurance Actuator
21 April 2017
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06 April 2017
Launch of 100DPC Multi-trim
17 March 2017
Launch of 840GS control valve
22 December 2016
IMI Critical to exhibit new technology at ADIPEC 2016
25 October 2016
New graduates join IMI Critical in four countries
22 September 2016
IMI Critical to take stand at ONS 2016 in Norway
16 August 2016
IMI Critical opens new China plant in Qingpu
27 July 2016
IMI CCI Korea celebrates 2,000 days of no “Lost Time Accident”
25 July 2016
Visit to IMI Z&J Germany by the Russian Economic Bureau from Bonn
11 July 2016
IMI Z&J Düren moves into modern offices
08 July 2016
IMI Critical Engineering forms strategic partnership with MRC Solberg & Andersen
05 April 2016
IMI Way Day 2016 date announced
01 March 2016
NEW IMI Eye – fourth edition
26 February 2016
IMI Critical co-locates China businesses
20 January 2016
IMI CCI Switzerland gains certification for new generation safety valves
18 December 2015
IMI Critical rise to Dragon challenge
30 November 2015
IMI STI achieves CRCC approval for new products
24 November 2015
IMI Truflo Marine Attend the Engineering Technology and Innovation Exhibition 2015
23 November 2015
IMI CCI Sweden secures new contracts on three continents
23 November 2015
IMI Critical Engineering appoints new petrochemicals head
05 November 2015
IMI CCI Czech Republic gains ‘Safe Enterprise’ certification
03 November 2015
IMI Critical announces 90mRMB investment in China
29 October 2015
IMI CCI SriCity wins regional safety award
27 October 2015
Key clients attend grand opening of new Aberdeen facility
23 October 2015
IMI companies ‘act as one’ to deliver for customer
02 October 2015
IMI CCI Sri City approved by NTPC
01 October 2015
IMI Critical Engineering showcases innovation at Valve World Expo Asia
28 September 2015
Nexen awards IMI Orton
25 September 2015
IMI Critical Engineering celebrates opening of new Jubail repair centre
23 September 2015
IMI Critical and IMI Precision join forces at Valve World Expo + Conference Asia 2015
21 September 2015
IMI Critical Engineering opening of new Jubail Repair Centre
18 September 2015
IMI CCI India manufactures first 1050MW turbine bypass valve
20 May 2015
Largest ever contract for IMI Critical Engineering
18 February 2015
New Houston facility opens
12 February 2015
IMI Critical completes acquisition of Bopp + Reuther
02 January 2015
IMI Critical takes family of brands to Valve World 2014
11 December 2014
IMI STI doubles size of Italian plant
20 October 2014



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Product - RTCH Scotch Yoke Hydraulic Actuators