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AC Motors & Gearmotors


Low-Speed Low-Speed Synchronous MotorsSynchronous AC Motors & Gearmotors - SMK Series

Low-speed synchronous motors provide highly precise speed regulation, low-speed rotation and quick bi-directional rotation. The basic construction of low-speed synchronous motors is the same as that of stepping motors. Since they can be driven by an AC power supply, they are sometimes called AC stepping motors.


Advanced SearchSafety Marks

Low-Speed Synchronous Rotation

The motor rotates at a speed proportional to and accurately synchronized with the frequency of the power supply. A fluctuation in load does not affect the rotation speed.

  • At 50 Hz 60 r/min (30 r/min for SMK014MA-*)
  • At 60 Hz 72 r/min (36 r/min for SMK014MA-*)

Precise Positioning

The motor can be stopped instantly by turning off the power supply. The stopping accuracy within the motor's permissible load inertia is ±10°.

Vertical Applications


Constant speed can be maintained even during lowering operations. Low-speed synchronous motors are suitable for applications where vertical operation at a constant speed is required.


Continuous Rated Capacitor-Run Motor

This is a capacitor-run motor that can be driven by a capacitor only. (An external resistance is needed for SMK5 type). This can be driven at a continuous rating even when bi-directional operation is required.

Superb Starting, Stopping, and Reversing Characteristics

If operated within the permissible load inertia, the motor can start, stop and reverse with 1.5 cycles (0.03 sec at 50 HZ, 0.025 sec at 60 Hz) of the power supply frequency.

Start-Stop Operation

Holding Torque

Since a permanent-magnet, multi-poled rotor is used, the motor has holding torque even when the motor is not energized. When used with a gearhead, comparatively high holding torque can be utilized. (When a larger holding torque is required, a DC power supply can be connected as soon as the AC power supply is cut off.)

Long Life, Low Noise GN-S Gearhead Available

GN-S GearThe new "long life, low noise GN-S gearhead" achieves a long rated life of 10,000 hours, twice the level of a conventional gearhead, by adopting innovative technologies and structure. Parallel Shaft models.


Select Power Supply below to view available products.

Product Lineup


Frame Size

Power Supply



Parallel Shaft
Parallel Shaft

1.65 in.
(42 mm)

Single-Phase 100/115 VAC

1.32 ~ 4.9 lb-in
(0.15 ~ 0.56 N·m)

72 r/min (60 Hz)
60 r/min (50 Hz)

2.36 in.
(60 mm)

Single-Phase 100/115 VAC 3.5 ~ 26 lb-in
(0.4 ~ 3 N·m)

3.54 in.
(90 mm)

Single-Phase 100/115 VAC 12.3 ~ 88 lb-in
(1.4 ~ 10 N·m)


Output Power

Power Supply



Round Shaft (No Gear)
Round Shaft
(No Gear)

1.65 in.
(42 mm)

Single-Phase 100/115 VAC 0.63 ~ 1.27 oz-in
(4.5 ~ 9 mN·m)

72 r/min (60 Hz)*
60 r/min (50 Hz)*

2.22 in.
(56.4 mm)

Single-Phase 100/115 VAC 3.5 oz-in
(25 mN·m)

3.35 in.
(85 mm)

Single-Phase 100/115 VAC 5.1 ~ 12.6 oz-in
(36 ~ 89 mN·m)

View Products = View all SMK Series Low-Speed Synchronous Motors

*Motor Speed for SMK014MA-A is 36 r/min (60 Hz) and 30 r/min (50 Hz)

System Configuration

NOTE: Motor includes capacitor and capacitor cap. SMK5 type also includes external resistor.

Motor & Gearhead ship separately and must be assembled (except for SMK0A-_A models).

Build a System Build a complete system online by selecting your base motor and adding all necessary accessories and/or controller.

Couplings / Brackets

Flexible Couplings

Flexible Couplings

These products are clamp type couplings used to connect a motor or gearhead shaft to the shaft of the equipment.

Motor Mounting Brackets

Mounting Bracket

This is an aluminum die cast mounting bracket for geared motors.

Long, horizontal holes make it easy to make fine adjustments during installation.

CR Circuit for Surge Suppression

CR Circuit

This product is used to protect the contacts of the relay or switch used in the forward / reverse circuit section or the instantaneous stop circuit section of a motor.

CR Circuit



Technology Training Videos

ORIENTAL MOTOR offers monthly Live Seminars as well as On Demand Training Videos.

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Related Seminar Videos



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