FAQ

FAQ

We have posted your frequently asked questions here. If your question is not posted here or if you cannot find your question, please feel free to contact us from the “Inquiries Form.”

*We will add and update the information posted below as needed in the future.

Index

Product Questions

Coupling

>> Coupling Q&As

SERVOFLEX(Metal Disc Couplings)

SPRFLEX(Jaw Couplings)

STARFLEX(Jaw Couplings)

STEPFLEX(Dual Rubber Couplings)

CENTAFLEX(Rubber and Plastic Couplings)

ETP BUSHINGS & POSI-LOCK

ETP BUSHINGS

ELECTROMAGNETIC CLUTCHES & BRAKES

SPRING-ACTUATED BRAKES

Electromagnetic Clutch & Brake Power Supplies

Belt-type Stepless Speed Changers

Zero-Max

TORQUE LIMITERS

ROSTA

Other Questions

Product Questions

Coupling

If a product comes with coupling standard hole processing, is set screw processing and the set screws included ?(e.g., setscrews, set screws, screws and locking screws)
We perform set screw processing with the number and size given in the catalog. The set screws are included with the product. Please check the details by requesting a product catalog with “Request Product Catalogs” or by searching for the product from the “Model Index Search List.”
If there is a keyway on the mounting axis on a coupling, what becomes of the allowable torque?
If you can use it while paying attention to the axis mounting position, the allowable torque does not change even if there is a keyway.
Is it possible to use a coupling fastener (inner diameter) as a spline?
This depends on the type of coupling and the type of spline. Please contact us from the “Inquiries Form” here.
How should I determine the amount of coupling axis insertion?
This also depends on the type of coupling. However, basically, please insert the axis over the whole length of the hub (flange). If the amount of axis insertion is insufficient, it may cause problems in extreme cases. For example, it could be a factor that induces a slip due to a decrease in the holding force, it may not be possible to fasten and it may not be possible to insert after the hub has become deformed.
There is a set screw as the axis fastening method for a coupling. However, there is a risk of it falling off due to the vibrations of the machine. Is there a good countermeasure for this?
There is a method of using two set screws in one screw hole as special support. Please contact us because we will examine the optimal method each time according to the hole diameter and machine specifications.
Is it possible to change the size and number of keyway set screws?
(Ex. AL-070 H17: 2-M4→1-M6)
Yes. However, this requires special support. Please contact us upon entering the details on the “Inquiries Form.”

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SERVOFLEX(Metal Disc Couplings)

What is the paint on the SFC bolts?
We produce this manually or by machine depending on the production situation of the product. If we produce it manually, we check with paint for whether there are any defects in the tightening of the torque wrench.
How should I determine the amount of SFC coupling axis insertion?
This also depends on the type of coupling. However, basically, please insert the axis over the whole length of the hub (flange). If the amount of axis insertion is insufficient, it may cause problems in extreme cases. For example, it could be a factor that induces a slip due to a decrease in the holding force, it may not be possible to fasten and it may not be possible to insert after the hub has become deformed.The amount of SFC coupling axis insertion

Nevertheless, even if the insertion length is not perfect, it may be possible to use it without problem. Therefore, please contact us using the“Inquiries Form” in that case.
Is it possible to mount the SFC even if there is a keyway on the mating mounting axis?
In principle, the mating mounting axis is a round axis. However, if using an axis other than a round axis for unavoidable reasons, please take care with the axis mounting position as in the figure below. This may lead to damage to the coupling body and a decrease in the axis holding force depending on the axis mounting position. We recommend using with a round axis to fully satisfy the performance of the coupling.
SFC　Proper Mounting Examples
Is it possible to combine the clamp system and the wedge system with SFF couplings?
Yes. Please indicate the hole diameter and the fastening type for each hub.
Is it possible to combine the clamp system and the wedge system with SFM couplings?
Yes. Please indicate the hole diameter and the fastening type for each hub.
Is it possible to additionally process a keyway to SFF and SFM clamp systems?
We can consider this depending on the hole diameter and keyway dimensions (width, height and tolerance). However, it may not be possible.
Is it possible to additionally process two keyways to SFH couplings?
We will need to make a determination each time depending on the keyway specifications (e.g., geometric tolerance and position). Please enter your desired specifications and contact us using the “Inquiries Form.”
I ordered one SFH unit, but two units were delivered. I only made arrangements for one unit, so haven’t you over-delivered on the number of units?
We are sometimes not able to pack only one SFH unit depending on the size. Therefore, we may send two units. However, please understand that we do not consider this an over-delivery.
Why is the allowable eccentricity not listed for the SFH-S even though there is a listing for the SFC/SFF?
Theoretically the single element type cannot allow eccentricity even for the SFC/SFF. However, the SFC and SFF are parts we assemble and ship; they are not parts we ship like the SFS and SFH. Therefore, it is difficult to adjust the center of the axis, so we have established allowable eccentricity (measurement error) to a degree that is no problem with performance.
What is the durability and aging of servo flexes (metal leaf spring couplings)?
We conduct torsion durability tests with a load exceeding the allowable torque. The servo flex has cleared 10 million times at the metal fatigue limit in this test. In addition, it is an all-metal material, so aging is extremely low and it can transmit torque with a high precision over a long period of time.
The durability and aging of servo flexes (metal leaf spring couplings)
When a coupling is mounted, the driven shaft runs out. What is the cause?
The runout of a driven shaft caused by a coupling is mainly attributed to the counterforce of the shaft caused by insufficient centering. All of the SERVOFLEX series are assembled using high-precision special jigs to ensure high concentricity of the bores on the left and right. The counterforce of the shaft is extremely small so the runout of the driven shaft can be minimized.
SERVOFLEX,Metal disc coupling from a third party
Noise and vibrations occurred during use of a metal disc coupling. Please tell me how to prevent them.
For a servo motor, noise and vibrations can be suppressed by setting the machine resonance suppression filter to its natural frequency in the control system. For a stepper motor, vibrations can be absorbed and suppressed by changing the rotation speed or using a STEPFLEX coupling with high damping ability.
Before and after adjusting the resonance filter of the servo motor
Can enough torque be transmitted using the clamping method for connection to the shaft?
Our torque transmission test uses a sufficient safety factor, so slip of the connection caused by the connection method will not occur when using the rated torque in the catalog. A keyway can be milled into the clamping hub. If you are interested, please refer to Keyway Milling Option.
Shaft holding power based on SFC-040DA2 bore diameter

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SPRFLEX(Jaw Couplings)

Is there a hole for the pilot hole of the AL?
No. The following center hole is processed.
The following center hole is processed.

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STARFLEX(Jaw Couplings)

I want to know the model of the ALS element.
It is EL. Please see the “ALS Product Page Specification Details” for details.
How long is the MIKI PULLEY STARFLEX service life?
If power transmission is your primary goal, select an appropriate coupling using the selection procedures of the catalog, then you can expect long-term use. Service life will vary with usage environment and conditions and is heavily affected by usage temperature and mounting misalignment. Contact Miki Pulley for details.
Can they be used in excess of the nominal torque?
They can, up to ten times daily when operating 8 hours per day, but not in excess of the maximum torque. This assumes startup torque of a motor with a low frequency of starting and stopping.
What exactly is a loose fit element?
These elements have a convex (crowning) shape to the torque transmission surface. They greatly increase the permissible mounting misalignment. They are also easy to assemble, since they set a loose fit with the hub. This can reduce the number of work steps.
Loose fit element,Tight fit element
Does MIKI PULLEY STARFLEX develop no-backlash as it ages?
MIKI PULLEY STARFLEX achieves no-backlash by preliminary compression of the element, so it may not be able to maintain nobacklash as the plastic ages. If you are considering using one in no-backlash mode over a long period of time, we recommend setting the service factor based on load property to a high value. If you require high precision control for a longer period, we recommend the SERVOFLEX series of metal disc couplings.
STARFLEX,Backlash as it ages
Is there any problem with an atmosphere in which solvent is applied to the ALS (STARFLEX) coupling resin (Element Spider) parts?
We need to make a determination each time about this depending on the type of solvent. Please tell us the solvent you will use and contact us using the “Inquiries Form.”
Is it possible to change the total length of the ALS (STARFLEX) coupling?
It is possible to shorten the hub. Please contact us each time about your required specifications. We are not able to lengthen the hub. We can propose the optimal couplings for you with other couplings (e.g., SFC), so please contact us using the “Inquiries Form.”

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STEPFLEX(Dual Rubber Couplings)

Does the STF element rubber material cause a delay in rotation transmission?
There are no delays at a level that hinders operation.

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CENTAFLEX(Rubber and Plastic Couplings)

Resonance occurs on equipment that is driven by diesel engines. What can I do about it?
If you are using an internal combustion engine (diesel engine, etc.) as your drive source, torsional resonance will occur when the natural frequency in the rotation direction of the torque transmission system as a whole coincides with the variable period of the rotational torque generated by the engine (vibration frequency dependent on rotational speed). Since occurrence of torsional resonance can damage couplings or shorten their service life significantly, it is necessary to avoid resonance points that can affect them. In general, with models with low torsional stiffness that use natural rubber-based elements, such as the CF-A and CM, the resonant rotation speed tends to be lower than low idle, while on models with high torsional stiffness such as the CF-H, it tends to be in a speed range that is higher than high idle. Any resonance point that may exist in the range of rotation speeds at which the engine is used can be shifted away from that range by changing the torsional stiffness of the coupling (accomplished by changing the type and size of coupling, the shore hardness, or the like).
What does the "pre-compressed construction" of CF-A models refer to?
It is a characteristic of rubber that its service life is longer when it is compressed rather than extended during use. It also has a longer life, even when compressed, if force is only applied to it after it has been somewhat compressed. This somewhatcompressed state is called pre-compression. CF-A models are assembled with pre-compression applied to the rubber body. The compressed portion has longer life, and even the pulled portion will not go into an extended state if the torque on it does not exceed a certain level, so a longer overall life is achieved.
Do rubber couplings have heat and maintenance issues?
When natural rubber is heated, it loses its surface oil, decreasing its elasticity and hardening it. While the progress of that hardening will vary with the temperature, when a CF-A coupling used inside an engine housing is subjected to heat, the rubber body surface hardens, so that when torque is applied to that part of it, cracks can start in the hardened layer, damaging it. As a maintenance guide, we recommend replacing the coupling when rubber hardness increases about 15 Hs from the pre-use level.
What is CENTA-LOCK?
Hubs can be mounted on shafts using a CENTA-LOCK mechanism. Tightening the clamping screw changes the shape of the spline part of the clamping hub, pressing it against the spline part of the shaft and completely locking the hub to the spline shaft. While size also matters, when the clamping screw is tightened to the stipulated torque, about one ton of axial holding force is generated per clamping screw. This means that under normal conditions of use, they are locked to a degree that you never have to think about.
Center lock mechanism on the clamping hub
Is it better to replace the CF-A bolts when replacing the rubber bodies?
We recommend replacement because it has a locking mechanism with microcapsule coating.
How many times can the CF-A bolts be re-tightened?
It is possible to re-tighten and re-assemble in a short time, but the effect of the locking mechanism will be reduced. However, we recommend replacement once used more than a certain period of time.
The CF rubber body is too tight and cannot be replaced? Is the rubber body I purchased correct？
The CF-A model has a structure in which pre-compression is applied to improve durability. Accordingly, it may be difficult to assemble.
The CF-B element has a notch depending on its size. Is this normal?
Yes. There are notches on the 140 and 140-H elements.
What happens if the CENTAFLEX series resonates?
If it resonates, it may melt due to internal heat generation and then break within a few minutes.
Please tell me what I should pay attention to in regards to the hole diameter listings of the CENTAFLEX couplings when ordering.。
When specifying the hole diameter, check the “When Ordering” section in our catalog and indicate in order the cylindrical hub hole (d1) and flange hub hole diameter (d2) after the model. Please note that the minimum and maximum hole diameters differ on the cylindrical hub side and flange hub side. We have listed the respective minimum hole diameters and maximum hole diameters in the dimensions section, so please check these. Please also thoroughly check the notes for each item.
Are the CENTAFLEX clamping hub specifications for zero backlash?
There is no backlash because there is complete fixation with a center lock function between the clamping hub and the axis. However, if the tightening torque of the clamping screw is lower than the specified tightening torque, it will not be possible to obtain sufficient holding force and backlash may occur. Tighten at the specified tightening torque using a torque wrench or similar. In addition, because backlash does not necessarily disappear in relation to products with backlash in the product specifications, please take care.

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ETP BUSHINGS & POSI-LOCK

Is it possible to use a resin hub with ETP bushing or a POSI LOCK?
No.

ETP bushing

What is the allowable rotational speed of the ETP bush?
This depends on the size of the ETP and the dimensions of the hub mounted to it. However, there is no problem using it even at about 3,000 min-1. Please contact us about applications with a high rotational speed.
Please tell me about the durability of the ETP bush.
The fatigue when using the ETP bush periodically at its allowable torque is approximately 500,000 times. The fatigue when using it periodically at 75% of its allowable torque is semi-permanent.
Durability of the ETP bush.
Who much does the ETP expand when pressure is applied to it?
This varies depending on the materials and shape of the mating hub. It is not possible to give a general rule. Make sure to select an ETP with the predetermined tolerance. Check the specified mounting tolerance of each ETP product with the “Materials at the Time of Selection.” There is a page called “Design Check Items” at the end of the section for each model. You can check the specified mounting tolerances from there.
What are the pressure medium (grease) components?
This differs depending on the model. There is one that use the highly safe food machinery lubricant (NSF H1 registered product) in place of oil as part of our lineup. (This is the ETP-E plus R TYPE.)
Does the ETP grease have an effect on the human body? It is there no problem even if it is stuck to food?
This differs depending on the model. Please contact us from the “Inquiries Form.” There is one that use the highly safe food machinery lubricant (NSF H1 registered product) in place of oil (made of stainless steel). (This is the ETP-E plus R TYPE.)
Are there any precautions for the hub to which the ETP bush is mounted?
As you can see in the figure below, if the outer diameter on the hub side is insufficient, it may succumb to the hydraulic force and the hub may become deformed. Make sure to check whether the minimum outer diameter on the hub side is sufficient when selecting an ETP bush. If the outer diameter of the hub is insufficient
Refer to the formula below for how to calculate the minimum outer diameter of the hub.

How to calculate the minimum outer diameter of the hub.
Can I use the ETP bushings for the shaft and hub with keyways in them?
You can use the ETP bushing by completely filling the keyway with epoxy putty for metals and then shaping it. If you use the device with keyways on the shaft and hub, the specified valued cannot be met, and the sleeve may be deformed and the device may become unable to be detached and attached again.
キー溝
Can I use the ETP bushing when the shaft and hub do not overlap the entire sleeve length?？
Please select a short sleeve so that the shaft and the hub overlap the entire sleeve length, or please consult with us. If there is a part of the sleeve that does not contact the shaft and hub, the deformation of that part of the sleeve is not controlled and the amount of deformation increases, so the sleeve will be deformed and enough friction force will not be able to be obtained. As a result, the specified value cannot be met. For details on the allowable range of the edge, see “Allowable Range of Edge” in “Items Checked for Design Purposes” for each model.
Can the rated torque be transmitted even if thrust load is applied?
The specified rated torque and rated thrust are the maximum rated values when they are applied independently. If the torque and thrust are applied at the same time, obtain the combined load and check that it is less than the rated torque.
If an ETP bushing slips once, can it be reused?
Whether or not it can be reused depends on the degree of slip. If the degree of slip is small, it can be reused. However, if you reuse it, you need to check it to make sure there is no scratch on the surface of the ETP bushing, shaft, and hub, and there is no deformation on the ETP bushing main body. And, if you reuse it, you need to remove the cause of the slip.
Is it possible to replace the ETP pressure screw? Do you sell them?
We do not sell or replace ETP pressure screws. In addition, if the pressure screw goes missing, air will enter into the hydraulic system and the fastening function may be lost. Therefore, we ask that you do not replace it.
Is the allowable torque of the ETP lower than the mechanical type?
This varies depending on the shaft diameter used. Therefore, we cannot say that is always lower. ETP products are characterized by fastening at the contact surface. Therefore, the large the axis diameter, the greater the allowable torque of the ETP product. We ask that you check the detailed specifications for ETP products and POSI LOCK products.
How many IP is the ETP-E-R equivalent to in terms of waterproofing standards?
It is not compliant with IP. Refrain from using it for a main purpose of waterproofing because it only has stainless steel specifications that are resistant to rusting.
Are there now no ETP-K, ETP-G and ETP-D types?
We have changed these models to PSL-K, PSL-G and PSL-D. Check the “PSL Products Page” for PSL.
What is the extent of the anti-rust strength of the ETP-E-C and ETP-T-C? Do you have any materials on the anti-rust effect?
We have applied electroless nickel plating, so they have an anti-rust strength greater than standard specifications. However, the anti-rust effect differs depending on the operating environment. Please contact us using the “Inquiries Form” when using in a special environment.

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ELECTROMAGNETIC CLUTCHES & BRAKES

Is it possible to create a dustproof cover for clutches and brakes?
The dustproof cover is currently only able to handle BXW models.
What is the life of clutch and brake products other than besides the workload (wear)?
In addition to the workload, there is the life of the electromagnetic coils and the mechanical life of springs due to thermal deterioration. The life of the electromagnetic coils equals the time in which they can be energized. The mechanical life is the number of times clutch and brake products are turned on and off with no load. Please contact us using the “Inquiries Form” for details.
Can I use clutch and brake products outside of the operating atmosphere?
It is possible with special support. Please contact us using the “Inquiries Form” for details.
Is it possible to control torque with an electromagnetic actuated type brake?
Some brakes can control torque by changing the current, but we do not handle those products.
What is the allowable number of times the release lever can be operated?
It depends on the model. It is not designed as something that always operates. Therefore, excessive operation may cause deformation. Accordingly, we recommend that you operate it about a few dozen times as a guide.
Is there a polarity (+ and -) in the stator leads of clutch and brake products?
No.

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SPRING-ACTUATED BRAKES

I don't see anything with the torque and response I need in your standard products. Can you customize something for me?
We can customize units in many ways: outfitting them for overexcitation power supplies or use of inrush current at motor startup, changing the frictional material, boosting torque, increasing response, extending the total energy (service life), suppressing heat generation, and more. Consult Miki Pulley for details.
Overexcitation power supply BEW-2FH
Can you handle cases in which standard products cannot be installed due to dimensional constraints?
Yes, we can. For example, we have a long track record creating slimmer units that deliver the same torque. These units can provide the same torque while being only about half as thick as the standard product, although this will vary with your conditions. Consult Miki Pulley for details.
What do you have for dealing with noise issues?
Spring-actuated brakes have a number of types of noises, such as (1) rattling generated by microvibrations during rotating, (2) armature pull-in and release noise, (3) friction noise (chirping) during braking, and (4) grinding noise under drive (when the brake is released). We have ways of reducing all of these. The figure below shows an example.
Noise issues
What are the grooves on the rear side surface of the power supply of the BXR-LE?
There are ways of fixing the location of the power supply (e.g., using metal fittings to mount it to the wall). These grooves are provided to mount the necessary metal fittings for that fixation.
The rear side surface of the power supply of the BXR-LE

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Electromagnetic Clutch & Brake Power Supplies

What is the BES input current?
It varies depending on the load. However, the rated current is as below.
BES-20-□□-1　1.6A
BES-40-□□-1　3.2A
BES-20-□□　　0.8A
BES-40-□□　　1.6A
Why isn’t the BEH recommended as a power supply for spring actuated type brakes even though it has DC 24 V output?
The BEH is an ultra-high-speed control type power supply. It is a product designed to control electromagnetic actuated type clutches and brakes with a high-speed and high-response. It cannot electronically perform control with a high-speed and high-response because the brake is applied with a spring in the case of spring actuated type brakes. Therefore, we do not recommend it as a power supply for spring actuated type brakes.

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Belt-type Stepless Speed Changers

Please tell me how to remove the belt of belt type transmissions (excluding AHS and RWP).
If possible, rotate the motor, rotate the speed change handle in the counterclockwise direction and then stop it at the maximum speed. If you rotate the speed change handle in the clockwise direction in this state, the belt will loosen, so you can remove it.（Movie）
Please tell me how to insert the belt of belt type transmissions (excluding AHS and RWP).
Set the pulley on the motor side to the minimum speed. Place the belt on the pulley on the motor side. If you hook the belt to the pulley on the driven side and rotate it halfway, the belt will insert itself.（Movie）
Please tell me how to remove the pulley PE (07 or above) on the driven side of ANS types.
It is fixed in place by tightening the hexagon socket head bolt in the center of the pulley. Accordingly, you can remove the pulley if you loosen that hexagon socket head bolt.
Can you sell only hollow shaft unit motors and speed reducers?
Basically, we cannot do this.
What is the rated current value of the ANW?
Although this is the current value of the motor alone, there is a sticker that gives the current value on the side of the moto. Please look there.
Can you replace oil for the RWM?
No.

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Zero-Max

Can you repair or part exchange the Zero-Max?
No.

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TORQUE LIMITERS

Please tell me how to replace the spring of the torque tender (torque limiter).
We ask that you do not replace the spring by yourself because disassembly is required.

ROSTA

Please tell me what the materials are of each part of the ROSTA tensioner.

Rosta tensioner material
Does the pulley idler RA come with fixing nuts and bolts?
Yes.
Does the sprocket idler N come with fixing nuts and bolts?
Yes.

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Other Questions

Please tell me how to request a REACH investigation.
Please contact us by filling out the model subject to the REACH investigation request with the “Inquiries Form.” It is faster to make a request from our website than by telephone.
When can I purchase products?
Please contact us from the “Inquiries Form.”
Please tell me how to request STEP data.
Please contact us by entering the desired CAD data model with the “Inquiries Form.” It is faster to make a request from our website than by telephone.
What is the format of the product CAD data?
The format of the CAD you can download from our website is as below.
2DCAD → DXF format
3DCAD → STEP format
We can consider creating 3DCAD with the IGES format, binary format and Parasolid format separately. Please contact us from the “Inquiries Form.”
Can you sell to me directly?
We can propose the optimal sales method for you. Therefore, please contact us from the “Inquiries Form” when considering a product purchase.
Do you handle timing pulleys and V pulleys?
No.
Is it possible to confirm the model from the serial number?
Basically, this is not possible.