Visit our webpage for Shindengen Rotary DC Solenoids to view all available models and for access to datasheets. 

Rotary Solenoid Design

The rotary solenoid's design starts from a standard flat face push-pull solenoid. The rotary solenoid then incorporates the mechanical design principle of an inclined plane to convert linear motion to rotary motion. There are three uniform inclined planes (spiral grooves) that are stamped into both the case and the armature, called "ball races". These provide both a means of converting linear motion to rotary motion and a secondary bearing system to support this rotary motion. (See Fig.1)

Features                                                                                    click here to view images as pdf

  • Ball races are specially designed to provide a constant torque output over the complete angle of rotation at 25% duty cycle.
  • The rotary solenoid uses an enclosed coil and therefore provides maximum magnetic efficiency.
  • The magnetic circuit is very short so high efficiencies in terms of torque output can be obtained, and energization / response times are very quick.

Starting Torque
The starting torque shown in our product catalog pages is the gross value output at 20°C. With the addition of the return spring, the solenoid's net output is the gross starting torque minus the return spring torque.

Rotation Angle Direction of Rotation
A. Use of an External Stopper (see Fig. 2)

The angle and direction of rotation are predetermined (and fixed) by the manufacturing process of the three ball races that are in the case and armature.

The degree of rotation can be reduced (example: a 35° right-hand (RH) rotation solenoid reduced to 30° RH rotation), by the use of an external stopper. However, to assure that the solenoid operates properly it is imperative that the solenoid armature always be allowed to return to 0° or unenergized position.

B. Direction of Rotation (see Fig. 3)
The normally accepted convention to describe the rotation of the rotary solenoid is that the direction of rotation is viewed from the armature plate (top) of the solenoid. Clockwise rotation is right-hand (RH) rotation, and counter clockwise rotation is left-hand (LH) rotation.

C. Rotation Angle Available
The rotation angles are available as follows:

Table 1
25°, 35°, 45°
RH and LH
25°, 35°, 45°, 67.5°
RH and LH
25°, 35°, 45°, 67.5°, 95°
RH and LH
SIZE490, 491
SIZE590, 591

Axial Travel
In Shindengen’s design for rotary solenoids linear motion is converted into rotary motion. The use of the inclined plane (ball races) also generate a small axial stroke; about 0.7 to 2.6 mm depending upon the amount of rotation and the size of the solenoid.

Table 2
SIZE 301 341 401 490, 491 590, 591 700 870,874
Axial travel (mm), approx. 0.7 0.9 1.2 1.5 1.6 2.3 2.6

Standard Available Accessories
The standard rotary solenoid is available with different accessories to meet your application requirements.

A:    Shaft extension on the armature plate
B:    Shaft extension on the base plate
D:    Dust cover over armature plate
R:    Return spring provided
T:    Tapped holes in armature plate

Operational Considerations
A. Temperature
The coil data of rotary solenoids shows the values at ambient temperature 20°C and with a standard heat sink. When a solenoid is used at the ratings mentioned in the coil data, it is designed so that the coil tempera­ture rises and reaches equilibrium at approximately 85"C. In applications where the ambient temperature is higher than 20°C or the heat sink is smaller than indicated in the catalog, possible thermal damage can occur. Temperature rise tests should be performed by the customer to assure that the coil does not reach 120°C. Custom coils can be constructed to operate at temperatures higher than 120°C without thermal damage. Please consult our sales staff for further details.

B.  Shaft Modifications
It is not recommended that the customer modify the shaft, as the shafts are fabricated before assembly. Special configurations can be supplied. Please consult our sales staff for further details.

C.  How to Use the "T" Feature (tapped armature plate)
The rotary solenoid does have axial movement in the armature plate position during energization and de-energization. When directly attaching a mechanism to the armature plate, the load must allow for free movement in the axial direction. Also, the attaching screws cannot be longer than the thickness of the armature plate or interference in the rotary motion will occur.
General Characteristics
Insulation class:  Class E (120°C), Lead wire class A (105°C)
Dielectric strength: AC 1000V 50/60 Hz 1 min. (at normal temp. and normal humidity)
Insulation resistance: More than 100 Mohm at DC 500V megger (at normal temp. and normal humidity)
Expected life: Standard life: 2 million cycles
Extended life: 10 million cycles
Long life:  50 million cycles
Note: Solenoid cycle life is very depended upon side load, frequency of use and environmental conditions. Cycle life tests should be performed by the customer.
How to Select a Rotary Solenoid
Before selecting a rotary solenoid, the following infor­mation must be determined:
A.  Torque
The actual torque required in the application should be increased using a safety factor multiplier of 1.5 to arrive at the torque value that should be used in your specification.

B.  Duty Cycle
Use the following formula to calculate duty cycle. Also note the maximum on time.
                                       On Time      
Duty Cycle (%) = On Time + Off Time x 100

C.  Rotation Angle
Rotation angle is determined by application requirements.

D.  Rotation Direction
Rotation direction is determined by application requirements (note direction of armature plate).

E.  Operating Voltage
Operating DC voltage is determined by the applica­tion and voltage available.
After determining the specifications listed above the correct solenoid for the application can be selected using the torque characteristics tables. Coil data is also provided in tables that use American Wire Gauge (AWG) for magnet wire. If the exact operating voltage is not in the coil data table use the nearest voltage shown in the table.
Note: When the operating voltage falls between 2 coil sizes, always use the higher AWG numbered coil to prevent potential thermal damage. To deter­mine the torque output of the solenoid after tempera­ture rise, please use the amp-turn gross torque tables located at the end of this technical guide after calculating the amp-turns.
Ordering Information
When ordering a rotary solenoid, the correct part number needs to be determined, from the following combination of characteristics (1-5):
[1]  M-Metric Thread
        F-SAE Thread
[2]  Solenoid Size (example - 490)
[3]  Coil Wire Size (AWG no.)
[4]  Angle of rotation, direction of rotation and accessories (see table 3)
[5]  Expected life (determined by selection of bearing type)
R-Standard Life Bearing
RE-Extended Life Bearing
RL-Long Life Bearing
Example of a complete part number:
[1] [2] [3] [4] [5]
F 490 26 141 R
The part number above distinguishes a rotary solenoid with [1] SAE threads; [2] size 490; [3] 26 AWG coil wire; [4] 35°right-hand rotation with accessories of armature side shaft extension and return spring provided; [5] standard life bearings.
For standard rotary solenoids (no modifications) the solenoid label will include the part number and date code. The date code identifies the year and week of manufacture.
Example part number: F 490 26 141 R 9401
F 490 26 141 R 9401
Coil Wire
Rotation & Accessories Rotary
& Bearing Life
Date Code
(year and week)
Note:  A custom solenoid (any modification to a standard design) requires the assignment of a special part number which will identify the custom model and date code.

Accessories Definition Table
When ordering a rotary solenoid use the following table to determine the correct code for rotation and accessories:
Accessories Clockwise Rotation (RH) Counter Clockwise Rotation (RH)
25° 35° 45° 67.5° 95° 25° 35° 45° 67.5° 95°
A         070 071 072 073 074 075 076 077 078 079
A   T     100 101 102 103 104 105 106 107 108 109
A   T   R 110 111 112 113 114 115 116 117 118 119
A     D   120 121 122 123 124 125 126 127 128 129
A     D R 130 131 132 133 134 135 136 137 128 139
A       R 140 141 142 143 144 145 146 147 148 149
    T     170 171 172 173 174 175 176 177 178 179
    T   R 180 181 182 183 184 185 186 187 188 189
  B       220 221 222 223 224 225 226 227 228 229
A B       230 231 232 233 234 235 236 237 238 239
A B T     260 261 262 263 264 265 266 267 268 269
A B T   R 280 281 282 283 284 285 286 287 288 289
A B   D   290 291 292 293 294 295 296 297 298 299
A B   D R 300 301 302 303 304 305 306 307 308 309
A B     R 310 311 312 313 314 315 316 317 318 319
  B T     340 341 342 343 344 345 346 347 348 349
  B T   R 360 361 362 363 364 365 366 367 368 369
  B   D   370 371 372 373 374 375 376 377 378 379
  B   D R 380 381 382 383 384 385 386 387 388 389
  B     R 390

Note:    Performance curves are at 20°C. No Load (return spring only)

Note:    Performance curves are at 20°C. 

Note:    Performance curves are at 20°C. No Load (return spring only)