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THK Linear Actuators

THK Linear Actuators

THK Linear Actuators - KR Series

The THK KR Series consists of a highly ridid outer rail with a U-shaped cross section, LM Guide units on both sides and a Ball Screw unit in the center.

  • High Rigidity, Compact and Space Saving
  • Normal, High Accuracy or Precision types
  • 30 mm up to 600 mm Stoke Lengths
  • Motor, Coupling, Flange kits (sold separately)
  • NPN, PNP, Optical Sensor available (sold separately)
  • Driver Option available (sold separately)


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THK Linear Actuator Construction

Because of its integral-structure inner block consisting of a highly rigid outer rail with a U-shaped cross section, LM Guide units on both side faces and a Ball Screw unit in the center, LM Guide Actuator model KR achieves a highly rigid and highly accurate actuator in a minimal space. In addition, since the housings A and B also serve as support units and the inner block as a table, this model allows signifi cant reduction of man-hours required for design and assembly, thus contributing to total cost cutting.

4-way Equal Load

Each row of balls is arranged at a contact angle of 45° so that the rated load on the inner block is uniform under loads applied to the inner block in the four directions (radial, reverse radial and lateral directions). As a result, model KR can be used in any mounting orientation.

Linear Actuator Load Capacity

Load Ratings

Model KR basic load ratings are equal in all four directions.

Linear Actuator Load Rating


Model KR is equipped with end seals and side seals for dust prevention as standard.

Linear Actuator Seals

High Rigidity

Use of an outer rail with a U-shaped cross section increases the rigidity against a moment and torsion.

Linear Actuator Rigidity

High Accuracy

Since the linear guide section consists of 4 rows of circular-arc grooves that enable balls to smoothly move even under a preload, a highly rigid guide with no clearance is achieved. Additionally, variation in frictional resistance caused by load fluctuation is minimized, allowing the system to follow highly accurate feed.

3 Types of Accuracy Grades Available:

  • Normal Grade: ±0.01 mm
  • High Accuracy Grade: ±0.005 mm
  • Precision Grade: ±0.003 mm

Accuracy Standards

Linear Actuator Accuracy

Product Lineup

Model Frame Size
Ball Screw
Max. Input
Torque (N·m)
Max. Input
Speed (r/min)
Linear Actuators KR20 Type 20 x 40 Normal, High Accuracy and Precision 30, 80, 130 1 0.207 6000
KR26 Type 26 x 50 Normal, High Accuracy and Precision 60, 110, 160, 210 2 0.622 6000
KR33 Type 33 x 60 Normal or
High Accuracy
50, 100, 200, 300,
400, 500, 600
6 or 10 1.244 4700

View Products = View all THK Linear Actuators

System Configuration

Sensor Set

Sensor Set

Optical proximity sensors for use with the THK linear actuators. Mounts to the dedicated sensor rail on the linear actuator.

Actuator Type
KR20 Type NPN
Photo Sensor (NPN)
KR26 Type NPN
Photo Sensor (NPN)
KR33 Type NPN
Photo Sensor (NPN)

Stepper Motor / Flange / Coupling Kits

Actuator Frame Size Motor Type
KR20 Type 42 mm 2-Phase Bipolar
KR26 Type 42 mm
KR33 Type 42 mm or 56.4 mm

1.8° or 0.9° 2-Phase Bipolar Stepper Motors

Stepper Motors

The PKP Series 2-phase stepper motors packages offer exceptional performance with low vibration. Available with a 1.8° or 0.9° step angle, standard or with a 200 / 400 line, 3 channel encoder or with an electromagnetic brake for vertical, load holding applications.

NOTE: Do not exceed the Maximum Input Torque for Actuator

Encoder Option

Encoder TypeOriental Motor offers two types of encoders, Incremental or Line Driver. The R2_ & R2_L are Oriental Motor's original encoders and are all 3 channel, 200 or 400 line encoders.

Electromagnetic Brake Type

Brake TypeThese products have built-in power off activated electromagnetic brakes. When power is accidentally cut off due to a blackout or other unexpected events, the electromagnetic brake holds the load in position to prevent it from dropping or moving. Also, when the motor is at standstill, it is held by the electromagnetic brake. It is possible to suppress the heate generated from the motor by turning off the motor current.




Stepper Motor Drivers

Oriental Motor high-performance, 2-phase bipolar stepper motor drivers offer advanced features, high torque and smooth motion in one of the industry's smallest microstepping drivers.



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