If you have ever purchased a Nabtesco Gearbox, you might know that there are specific steps that need to be taken to ensure proper installation and operation of the gearbox.
If some of the steps are performed improperly or missed completely, issues may arise during installation and operation of the gearbox.
In this article, we are going to review the installation procedures for Nabtesco gear reducers and go over some common questions and troubleshooting issues.
Common Installation Questions and Issues
Here are a couple questions related to gearbox installation that we see:
- Why is my gearbox not returning back to zero?
- Why am I seeing high backlash and E-stops that are damaging the gearbox?
Most often, the solutions to these issues are directly related to the gearbox installation.
Ensuring correct fastener size and placement along with tightening torque settings are some of the most commonly found installation issues among customers and new installers.
Following the Gearbox Installation Manual
With every purchase of a Nabtesco Gearbox, you will receive the applicable installation manual relevant to your product.
Let’s take a few minutes to look at the installation manual for our RD2 series and walk through some of the highlighted items that are most often the solution.
Preparation of required component
The components listed in the image below are required for installation of the gearbox, and needed to be prepared prior to installation.
For the correct shape and dimension of the gearbox, please refer to the separately provided outer dimension drawings.
Parts will need to be made to attach the gearbox to the rest of the structure, both the stationary supporting structure and to whatever is being rotated (Case installation component and shaft installation component in the drawing below).
Please design these while referencing the outer dimension drawings and the 3D models that are both available on the website (for RD2 and other catalog items) and by request.
The recommended tolerancing and GD&T for these components is listed in the installation manual, but please contact us if you have any questions and we will be happy to support you.
IMPORTANT: The actual components may differ from the required components shown in the above illustration, depending on the customer’s equipment.
Mounting Bolts and Fasteners
Reduction gear mounting bolts are one of the most important features, and most installers use something other than what Nabtesco recommends.
Fasteners used to mount the gearbox are incredibly important to the overall performance. In particular, the number of bolts, bolt strength, and also the tightening torque used when installing the bolts.
If these are not correctly selected and installed, problems such as slippage may occur.
Please review this before proceeding with installation:
It is very important to use every single through/tapped hole that is on the output face, gearbox case/outer diameter, and motor/input side to ensure proper performance.
Reduction Gear Mounting Bolts
The recommended fastener size, quantity and strength class are given below in Table 4-1, Table 4-2, and Table 4-3 for catalog spec RD2 gearboxes.
For the products not included in the catalog, prepare bolts according to the size and quantity as indicated in the separately provided “Outer dimensions” drawings and specification sheet.
Select the appropriate bolt length based on the mounting dimensions of the separately designed components. Pay extra attention to the tapped holes on the gearbox, if the bolts are too long and bottom out torque will not be able to be properly transmitted.
IMPORTANT: Note that the number of bolts for the case installation component is different depending on the input type.
Serrated Lock Washer for Hexagon Socket Head Cap Screw
Below are the serrated washers that Nabtesco recommends and uses with all installations to further prevent slippage of the fasteners:
- Name: Belleville spring washer (made by Heiwa Hatsujyo Industry Co., Ltd.)
- Corporation symbol: CDW-H, CDW-L (only for M5)
- Material: S50C to S70C
- Hardness HR40 to 48
IMPORTANT: When using any equivalent washer, select it with special care given to its outside diameter.
The RD2 series does not require liquid sealant on any surfaces, but it is required on other gearboxes that are not sealed and do not have an o-ring or oil seal on the installation surface.
In this case, the outline drawings will include the area that needs to be sealed using liquid sealant.
The liquid sealant that Nabtesco recommends is listed in the table below.
NOTE: Do not use the above liquid sealants if the component of the customer’s device is made of copper or copper alloy.
Bolt Tightening Torque
Once all of the fasteners and serrated lock washers are prepared, the next step in the process is tightening the bolts.
Note: If your torque wrenches are in ft-lbs, you will need to convert them into Nm (Newton Meters).
A failure or slippage during operation may occur if the bolts are over or under torqued. The bolt tightening torque can be found in the table below, and can usually be found on the outline drawings as well.
IMPORTANT: If aluminum or stainless-steel is used for the bolt, limit the tightening torque. When tightening the bolt with limited torque, confirm that there is no strength problem by taking the transmission torque and load moment into due consideration.
Servomotor Installation Walkthrough
Another important area with the RD2 is the orientation of the bushing (when a bushing is needed). Included below is a quick rundown of the installation process and things to look out for.
Installing the Servomotor, pulley and reduction gear
This section describes the procedures for installing the servomotor onto the input side of the reduction gear for the straight and right angle RD2 units and also the procedure for the pulley type RD2 units, as well as the installation direction for the hollow shaft series.
For the straight input type and right-angle input type
Perform the following steps while observing the following precautions:
- Wipe the outside of the servomotor shaft and the clamping surface inside the coupling with a clean cloth. (Check that the clamping bolt is not tightened).
- When using a bushing, wipe the inside and outside of the bushing using a clean cloth.
- Before installation, check that there are no scratches on the inside of the coupling, bushing, and motor shaft that could interfere with installation.
- Make sure that there is no foreign material or oil on the outside of the servomotor shaft, the clamping surface of the coupling, or the inside and outside of the bushing.
- Align the clamping bolt of the coupling with the through hole used for access that is located on the motor flange.
- When inserting the bushing, align the slit of the bushing and the slit of the coupling (See Fig. 5-7 for the positional relationship between the bushing and coupling).
- When using a bushing with a V groove on the circumference, orient the V groove toward the reduction gear side and then insert the bushing.
IMPORTANT: If the slits of the bushing and coupling are not aligned, proper tightening force cannot be achieved. When using the busing with a V groove on the circumference, orient the V groove toward the reduction gear side. If the direction is not correct, proper tightening force cannot be achieved.
Going through these critical steps before, during and after installation will ensure proper mounting of your Nabtesco gearbox.
If you should have any questions, please feel free to contact us at any time and we will be more than happy to answer any and all of your installation questions.