Valve actuator

SMB series


High performance and reliability demonstrated by achievements

Limitorque valve control SMB series

Limitorque SMB series valve actuators have many achievements in the fields of basic industries, such as thermal and nuclear power plants.
Superior performance is maintained for a long period of time by strong materials, highly accurate processing, design with high margin, and various protection features.
With eight unit sizes and a variety of reduction gear ratios, torque ranges of up to 27,000 N


  • – Thermal, nuclear, and hydropower plants, petroleum oil, chemical, ship, vessel, and papermaking.
  • – SMB series actuators can be attached directly to multi-turn-type valves (such as hydraulic gate, gate valve, glove valve, and through gate).
  • – They can be attached to part-turn-type valves (such as butterfly valves, plug valves, and dampers) in combination with an actuator for a part-turn-type valve.


  • Single-touch switching between manual mode and electric mode

    • – Operating the declutch lever switches to the manual mode, and activating the motor restores to the electric mode automatically.
    • – The auto-declutching function (SMB-0 and higher, option) that switches to the manual mode by turning the hand wheel is also available. (If the auto-declutching function is available, activating the motor also restores to the electric mode automatically.)
  • High-precision geared limit switch

    • – The operating point can be set at any position within the entire stroke.
    • – The limit switch is operated by the intermittent gear without fail. The preset position does not shift.
    • – Various contact types ranging from 2-line 8-contact to 4-line 16-contact (option) can be selected according to the application.
  • High-performance torque switch

    • – The operating point of the torque switch can be set to any value. It protects the valve and drive mechanism from an overload in both the opening and closing directions without fail.
    • – The rotary type equipped with the 1a and 1b contacts in both the opening and closing directions and the open type equipped with the 1b contact in both the opening and closing directions are available.
  • Optimized motor

    • – This product is equipped with a strong torque motor that is specially designed for driving the valve as standard. Because this product is the low inertia type, the shock generated at the time of a stop is small, and braking is not required at normal opening and closing speeds.
    • – This product can be selected from among various sizes, according to the load.
    • – Air, gas, oil, and servomotors can also be designated according to the protection type and power source.
  • Enhanced control functions

    • – Integral control, consisting of various control devices, is applicable to the control station (control panel) and computerized control.
    • – It enables development into a centralized system that networks multiple actuators.
  • Highly-durable gear train

    • – Worm gears and worms are made of aluminum bronze and carbon steel or chrome molybdenum steel, respectively. They can withstand high output and loads and maintain superior performance over a long period of time.
    • – Optimum materials are used for the respective gears according to the loads, and extreme pressure grease is filled in the sealed gear case.
    • – Ball bearing is used. A taper roller bearing is used for the output shaft that receives thrusts to realize stability-oriented design.
  • Easy maintenance

    • – The stem nut has a dual (two-piece) structure. The drive sleeve and stem nut are detachable because they are engaged with a spline.
    • – When replacing the stem nut, the actuator and electric wire do not need to be removed.
    • – Because the motor and worm gear have independent structures, the self-locking feature prevents the valve from operating under its own weight even with the motor dismounted, if the worm has one tooth. (In the case of SMB-000,00, the self-locking feature is canceled when switched to manual mode.)


Unit size SMB-000 SMB-00 SMB-0 SMB-1 SMB-2 SMB-3 SMB-4 SMB-5T
Mechanism and specifications Allowable torque N・m 170 360 1000 1500 2700 6100 11500 27500
Allowable thrust kN 30 62 105 200 320 620 1100
Minimum and maximum stem diameter*1(mm) Exterior thread 2PC 32以下 20-46 24-60 38-73 42-86 55-127 60-127
Interior thread 2PC
Maximum keyway
Maximum keyway
Output shaft rotation frequency(min-1)*4 60Hz 30 minutes (20 %) rating 17.0-51.0 15.6-73.8 17.2-62.6 19.2-62.5 20.6-72.8 16.4-47.4 13.6-32.8 7.4-16.3
15 minutes (40 %) rating 16.0-48.0 14.7-69.5 16.2-59.0 18.1-58.8 19.4-68.6 15.4-44.6 12.8-30.9 7.0-15.3
50Hz 30 minutes (20 %) rating 14.0-42.0 12.8-60.8 14.2-51.6 15.8-51.5 17.0-60.0 13.5-39.0 11.2-27.0 6.1-13.4
15 minutes (40 %) rating 13.5-40.5 12.4-58.6 13.7-49.7 15.3-49.6 16.4-57.8 13.0-37.6 10.8-26.1 5.9-13.0
Standard reduction rate of manual type 2.86
4.38 21.71 25.23 22.30 28.38 33.69 269.8
Attachable motor number*5 #2
Attachable actuator BA (Allowable thrust: 26 – 1,200 kN, for multi-turn-type valve)
HB (Allowable torque: 0.83 – 200 kN·m, for part-turn-type valve)
H (Allowable torque: 390 – 1,100 kN·m, for part-turn-type valve)
Electric and control specifications Torque switch 1a and 1b in both opening and closing directions (rotary type)
Geared limit switch 4 contacts (2a, 2b) × 2 lines (standard)
Motor Power supply “200 V AC class, 400 V AC class/50 Hz, 60 Hz
100 V DC class, 200 V DC class”
Heat resistance class Class E (standard), class B, class F, and class H (option)
Rated time 15 minutes or 30 minutes (standard)
Space heater Option
Indication light Option
Push-button switch
Position transmitter
Electromagnetic switch
Proportional braking system
Protection type Protection structure Standard (IP55), water resistant type (IP67)
Explosion-proof structureExplosion-proof structure Pressure-resistant explosion-proof structure (such as d2G4 and d3aG4)
Increased-safety explosion-proof structure (such as ed2G3 and ed3aG3)

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