Frequently Asked Questions (FAQ)

Here are questions frequently asked by customers and our answers.

Contents

About Products

Couplings

▶Miniature Couplings

Q. Can I order couplings with shaft hole diameters that are not listed in the catalog? (Coupling Shaft Hole Additional Modification Service)
Q. Can I use a key?
Q. What is the insertion amount of the shaft?
Q. What is the electrical insulation?
Q. What is the required space around the coupling?
Q. What are the methods for fixing the shaft?
Q. How can I determine the transmittable torque of the coupling?
Q. Which jaw type coupling (MJT/MJB) sleeve should I use?
Q. How can I manage the tightening torque?
Q. Can I use a shaft that has a D-cut shaft or key groove?
Q. The axis slipped. What should I do?

▶Flanged Shaft Couplings

 Q. Which fitting should be attached to the motor when assembling the flexible flanged shaft coupling?

Special Screws

Q. I want a screw that's not listed in the catalog.
Q. What is the thread pitch of the product?
Q. What is the tightening torque of the screw?

Others

Q. Are there overseas distributors?
Q. I want a catalog.
Q. I'd like a "RoHS directive compliance certificate" to be issued.

About Products

Couplings

Q. Can I order couplings with shaft hole diameters that are not listed in the catalog? (Coupling Shaft Hole Additional Modification Service)

Yes, you can. Same-day shipping on working days is available starting at 1 unit.
Please take advantage of our convenient shaft hole modification service.
➡Couplings Bore Additional Modification Service
Recommended tolerance for shaft diameters is h6 and h7.

Q. Can I use a key?

Couplings with key grooves are standardized for the MJT, MOR, and MOM Series.
Even with a coupling without a key groove, a key will be usable by taking advantage of our "New JIS Key Additional Modification Service".
➡ Couplings Bore Additional Modification Service
Applicable shaft hole diameter: φ8 or more, φ30 or less.

Q. What is the insertion amount of the shaft?

For the length of the shaft that should be inserted into the coupling, we recommend the hub length (L dimension) listed in the dimension table.
If the inserted amount is too short, the shaft may slip or the clamping part may break.
If the inserted amount is too long, there may be shaft interference within the coupling, leading to damage.
An insertion amount exceeding L can be used if there is no interference between the shaft and the inside of the coupling when assembling it into the equipment.

Q. What is the electrical insulation?

It is the insulation for electricity between the two hubs of the coupling.
The electrical resistances of the couplings that use rubber/resin between both hubs are as shown in the table below.


Product Code Electric resistance value
XGT2/XGL2/XGS2 Not less than 2MΩ
XGT-C/XGL-C/XGS-C Not less than 10kΩ and not more than 1MΩ
MJC/MJS/MJB/MJT Not less than 2MΩ
MOR/MOL/MOS Not less than 2MΩ
MOHS-C Not less than 2MΩ
MOP-C Not less than 2MΩ
MSXP Not less than 2MΩ
MSF Not less than 2MΩ

Details available here.
➡Glossary

Q. What is the required space around the coupling?

Please refer to the outer diameter and total length of the coupling to determine the required space.
Note that in some sizes, the head of the bolt may protrude out of the outer diameter.
Details available here.
➡Minimum rotation diameter

Q. What are the methods for fixing the shaft?

●Set screw type
●Clamping type / Split type / Semi-split type
●Key type (Key + Set screw / Key + Clamping)
●Bushing type
●Adapter + Clamping type
are available.

Details available here.
➡Installation and maintenance of the coupling

Q. How can I determine the transmittable torque of the coupling?

Please check the rated torque for the transmittable torque.

For the clamping type, the rotating shaft may slip below even the rated service torque and torque transmission may not be possible, so be sure to check the slip torque as well. If the slip torque is small, the transmission torque can be increased using the key.

Q. Which jaw type coupling (MJT/MJB) sleeve should I use?


●Selecting from 4 color variations
The hardness of the sleeve is distinguished by color.
Select green/red if high torque transmission is required.
Select blue/white if allowable misalignment is prioritized.

●Selecting from the two tight fit / easy fit variations
Select tight fit if rattling should be minimized.
Select easy fit if the ease of assembly is prioritized.

Q. How can I manage the tightening torque?

Tighten the screw at the screw tightening torque listed in the dimension table.
Use a torque wrench or torque screwdriver to tighten the screw.
If the tightening torque is smaller than the value listed in the catalog, the shaft may slip. Also, the screw may become loosened.
If the tightening torque is larger than the value listed in the catalog, an excessive load may be applied to the coupling or bolt, which may result in damage.

Q. Can I use a shaft that has a D-cut shaft or key groove?

Set the D-cut surface as the set screw fastening position when using set screw types.
As a rule, use round shafts with clamping types.
If a D-cut shaft is used, excessive load may be applied depending on the mounting position of the D-cut side due to hex socket head cap screw tightening, which may result in damage. If you have no choice but to use 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.
Details available here.
➡Mounting on a D-cut shaft

Q. The axis slipped. What should I do?

●Make sure that the screw was tightened at the specified tightening torque.
   See the dimension table for the tightening torque.

●Check the slip torque of each coupling.
   If the load torque exceeds this value, the coupling may slip.

●Slippage can be prevented by using the key.
  Details available here.
  ➡Couplings Bore Additional Modification Service

Q. Which fitting should be attached to the motor when assembling the flexible flanged shaft coupling?

Although there is no difference in performance as a coupling with either specification, the bolt set is removed from the coupling on the bushing when replacing the rubber bushing, so we recommend an installation method that provides more room in replacement work.
When using a pump, the "bolt side" is often mounted on the motor and the "bushing side" is mounted on the pump.

Special Screws

Q. I want a screw that's not listed in the catalog.

We can manufacture it starting at 1 piece.
Please indicate the thread diameter, screw length, thread shape and quantity.
Material, surface treatment, and special machining can also be selected. Please feel free to contact us below.

 Click here to contact us regarding special screws

Q. What is the thread pitch of the product?

If the thread pitch is not listed in our catalog or website, the product has coarse threads. (Diagram 1)
The thread pitch is listed for those with fine threads. (Diagram 2)
This is a general notation method that complies with JIS B 0123.
See here for the thread pitch of coarse thread screws.
➡General-purpose metric screw thread
For products that standardize both coarse and fine threads, the thread pitch may be indicated even for the coarse thread type. (Diagram 3)

Q. What is the tightening torque of the screw?

Refer to each product page for the tightening torque.
See here for products that do not list the tightening torque.
➡Mechanical properties of tightening parts made of carbon steel and alloy steel

Others

Q. Are there overseas distributors?

Please refer to the "Overseas Distributor List".
➡Overseas Distributor List

Q. I want a catalog.

We distribute it free of charge.
➡Request Mechanical Components Catalogs (free of charge)

Q. I'd like a "RoHS directive compliance certificate" to be issued.

A "RoHS directive compliance certificate website issuing system" is available.
It can be used from "RoHS Directive Compliance (Certificate Issuance)" at the bottom of the page.
➡Requesting RoHS Directive Compliance Certificate

Customer Service

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  • Technical Question
  • Customization Products
USA and Canada

NBK America LLC

9:00 to 17:00 on weekdays, Eastern Standard Time

Asia and Europe

Nabeya Bi-tech Kaisha

8:00 to 17:00 on weekdays, Japan Standard Time