Date Published:Jun. 11. 2014 Date Updated:Jan. 29. 2024

Mounting and Maintenance

Mounting and Maintenance


Coupling and Single-axis Actuator Assembly Method

Here, we explain how to assemble the coupling and single-axis actuator in an easy-to-understand video.

Alignment adjustment

  1. Although flexible coupling permits misalignment and transmits rotation angle and torque, if the misalignment exceeds the allowable value, vibration may occur or the life may be rapidly shortened. Be sure to perform alignment adjustment.
  2. Shaft center misalignment includes eccentricity (parallel error of both shaft centers), angular (angle error of both shaft centers), and end-play (shaft direction movement of the shaft). Adjust the shaft alignment so that it is not more than an allowable value described in the Dimension/ Performance table in this catalog.
  3. The allowable values of misalignment described in the Dimension/Performance table are for the case where any one of eccentricity, angular, and endplay occurs independently. Mixing of two or more misalignment causes each of the allowable values to be reduced to half.
  4. Misalignment may occur not only in mounting into the device but also due to vibration, thermal expansion, and shaft bearing abrasion during operation. Therefore, misalignment is recommended to be not more than one third of the allowable value.


Angular alignment (center matched)

Angular alignment (center unmatched)

Mixture of eccentricity and angular alignment


Run out

Shaft insertion length

For the length of the shaft that should be inserted into the coupling, we recommend the hub length (L dimension) listed in the catalog.
If the insertion amount is longer than the L dimension, check that there is no interference of the shaft inside the coupling.
If the inserted amount is too short, the shaft may slip or the clamping part may break.

Mounting on D-cut shaft

For clamping type

As a rule, use round shafts with clamping types.
When using D-cut shafts or shafts with key grooves, mount the D-cut surface or key groove in a position which avoids slits and bolt spot facing.

  • For clamping types with 1 hex socket head cap screw
  • For clamping types with 2 hex socket head cap screws
  • If the D-cut surface or key groove is not in the recommended position, the clamp part may be damaged if excessive load is applied due to hexagon socket head cap screw tightening.

    For set screw type

    Set the D-cut surface as the set screw fastening position when using set screw types.

    Rotation Diameter

    Rotation diameter refers to the larger of the coupling outer diameter (φA) or the diameter with the bolt head protruding (φA1) while rotating.
    When using couplings in narrow spaces, pay attention to the rotation diameter. Refer to the table below for rotation diameter details.
    The rotation diameter is calculated based on the reference dimensions. As it fluctuates according to tolerance, build a margin into your design values.

    Rotation diameter (by coupling type)


    There are seven types of shaft attachment methods as follows. Select a method according to your needs.

    Set screw type

    This is low cost and most common attachment method. However, since the screw point directly contacts the shaft, note that it may damage the shaft or make it difficult to remove the unit.

    Clamping type

    The bore is contracted by tightening force of the screw to clamp the shaft. Mounting and removal can be easily conducted, which does not damage the shaft.

    Split type

    the bore portion can be completely divided. Therefore, it can be easily mounted or removed without moving the device. In addition, the shaft is not damaged.

    Semi-split type

    This is an attachment method in which one side of the hubs is clamping type and the other side is split type. The device can be connected only on the split type side while keeping the clamping type side attached on the shaft.

    Key type

    As with set screw type, this is a general attachment method and can be applied to the transmission of relatively high torque. To prevent the movement in the shaft direction, this is used together with set screw type and clamping type.

    Bushing type

    Attachment method using taper wedge effect enables secure and stable attachment. This is suitable to high torque transmission and is the most appropriate for the spindle of a machine tool.

    Adapter + Clamping type

    This is a type made by inserting an adapter into the clamping type so as to be applied to 1/10 taper shaft of the servomotor.

    Installation Method/Maintenance Couplings