With synchronous belt power transmission, pitch center line on which the force acts is outside the tooth tip of belt sprocket, so transmission is possible by applying appropriate tension.

It is desirable to set an installation tension for ordinary transmission applications using the recommended value described in the catalog as a guide.

For applications where positioning accuracy is important, set it higher within the range that does not exceed the maximum value listed in the catalog.

When setting an installation tension below the recommended value due to load condition or convenience of device, set it while checking whether vibration and noise increase and whether there is a problem with transmission such as tooth jumping.

Excessively high or low installation tension may result in premature breakage of synchronous belt.

While it is preferable to move one of shafts for adjustment, there is also a method of using an idler for adjustment.

As a general rule, install the idler on the slack side of the synchronous belt so that it can be fixed after adjustment.

1. ①Use of Tsubaki Belt Tension Meter T-ACE

   Can be checked easily and accurately by using the sound wave formula belt tension meter "Tsubaki Belt Tension Meter T-ACE" that measures using the natural frequency of the belt.

2. ②There is a method to check the amount of deflection caused by pushing synchronous belt.
   1. Accurately establish the parallelism of all shafts including the idler shaft and belt sprocket alignment.
   2. Apply a push force (F) to the center of the span of the synchronous belt.
   3. Apply a tension that makes the deflection（δ）of the synchronous belt 1.6 mm per 100 mm of span.

[Click to enlarge ]

• 

  
  F：Push force required for deflection（δ）at the center of the span t N{kgf}
• Ti：Initial tension N{kgf}
• Y：Correction factor
• δ：Deflection mm=0.016t
• t：Span length mm
• C：Distance between shafts mm
• Dp：Pitch circle diameter of large belt sprocket mm
• dp：Pitch circle diameter of small belt sprocket mm
• L：Belt length mm

For 2-shafts (2 belt sprockets), measure at the center of the span.

For multiple shafts (three or more belt sprockets and idlers), measure at the point where the span is longest. More stable measurement is possible.

Installation tension can be lowered to the extent that the tooth jumping does not occur. Occurrence of tooth jumping varies depending on the operating conditions, so please check with the actual machine.

Synchronous belt does not run in the center of belt sprocket even if the belt sprocket is aligned correctly, and has property of shifting to either side.

Although its force is very weak, poor alignment of belt sprocket may cause it to travel closer to the edge of belt sprocket and be strongly pressed against the guide flange, resulting in damage and cut.

Also, the guide flange may fall off.

Adjust the alignment of belt sprocket within the allowable range listed below.

■How to adjust the belt sprocket

There are two types of elongation that occur in synchronous belts.

1. ①Elastic elongation (Load elongation )

   Elongation that occurs when a load is applied to the synchronous belt. It will be returned to original length when the applied load is removed.

2. ②Permanent elongation (Operation elongation )

   Elongation that cannot return to original even after the load applied to the synchronous belt is removed. It is mainly caused by initial contact and wear.

With a properly selected synchronous belt, wear of tooth fabric progresses, and then belt teeth are missing.

In addition, if diameter of belt sprocket is small or if there is a lot of bending in a multiple-shafts layout, bending fatigue of cord may lead to cutting.

As mentioned above, life is when synchronous belt loses its ability to accurately engage and transmit with belt sprocket.

Inspect synchronous belt regularly, and if any abnormal symptoms such as scratches or tooth fabric wear are found on appearance, replace it before belt teeth missing or synchronous belt cutting.

Life end may appear as vibration or noise, but some are subtle and difficult to know in advance.

Inspect synchronous belt regularly, and if any abnormal symptoms such as scratches or tooth fabric wear are found on appearance, replace it before belt teeth missing or synchronous belt cutting.

Tsubaki Ultra PX Belt makes it easy to check wear of tooth fabric by exposing base rubber, so it is easy to decide whether to replace it.

Before use

After use

Because synchronous belt is not metallic, there is no fatigue limit, and fatigue and wear will occur during use, resulting in damage.

In addition, it is very difficult to specify time to reach life end because durability time varies greatly depending on conditions and layout used.

We recommend replacement within max. 5 years, considering aging of material.

Unlike metallic chains and gears, synchronous belt's teeth are rubber materials covered with nylon fabric, so they are not suitable for transmission with only one tooth, and must be loaded with multiple teeth. If number of teeth engaged with belt sprocket is less than 6, load per tooth will increase, resulting in tooth chipping.

If number of teeth engaged is 5 teeth or 4 teeth, add "meshing correction factor" described in the catalog to select.

For drive belt sprockets, make sure that number of teeth engaged should be 6 or more and engagement angle should be 120 degrees or more.

Avoid using combinations in this part because small diameter belt sprocket rotates at high speed, which promote bending fatigue of synchronous belt cord inside and shortens its life.

When the circumferential speed of synchronous belt is fast, the following phenomena may occur.

1. ①Transmission capacity may decrease due to the centrifugal tension generated in synchronous belt.
2. ②Life may be shortened.
3. ③If the speed of belt sprocket exceeds 33m/s, or more, run-out or vibration may occur. Balance the belt sprocket.

When selecting a synchronous belt, it is recommended to examine the torque in consideration of the characteristics of servo motor.

Please contact us as it can be manufactured depending on the belt width.

Guideline is 1.5 times the total height of syunchronous belt, but it varies depending on product. Please contact us.

Loop type endless synchronous belts are manufactured using a mold, so belt lengths not listed in the catalog cannot be manufactured.

Oil resistance of "Ultra PX Belt Oil-Proof Type" is based on the in-house test results using general lubricant and cutting fluid. Therefore, resistance to all oil types and usage conditions is not always guaranteed.

Please check by the actual machine or contact us for the applicability of individual oil types and usage conditions.

Generally, if oil or water adheres to synchronous belt, it will swell and will not engage with belt sprocket, causing a decrease in transmission capacity and premature breakage. Especially, it cannot be used in oil or water.

Tsubaki offers "Ultra PX Belt Oil-Proof Type" and "PX Belt Water-Proof Type" that have improved durability in environments where oil and water are misty.

Use in a normal environment of -15℃ ～ 80℃. Some syncronous belts can be used up to 90℃ under certain conditions.

Please contact us for details.

PX tooth profile is Tsubaki original tooth profile and is not compatible with other companies. Please use it together with Tsubaki belt sprocket.

Precautions are summarized in the catalog "Synchronous Belts & Belt Sprockets". Be sure to read the "Instruction Manual" pages before use.

Synchronous belt hardly stretches even when force is applied.

Move belt sprocket shaft / idler shaft before installing it on belt sprocket.

Do not attempt to over the guide flange of belt sprocket forcibly, as this may cause an accident.

For 2-shafts transmission without an idler, prepare an adjusting margin of inter-axial distance.

■Adjusting margin of inter-axial distance

Units ：mm

	Belt length	Types
		P2M・P3M・P5M UP3M・UP5M	P8M・P14M UP8M・UP14M
△Co	Up to and incl. 500	3	3
	500～1000	5	5
	1001～2000	10	10
	2000以上	15	15
△Ci	Common	10	15

[Click to enlarge ]

Use the synchronous belts in a clean environment.

Protect synchronous belt and belt sprocket by covering it when used in dusty atmosphere where it may be exposed to excessive water, oil or solvents. Please consider "Ultra PX Belt Oil-Proof Type" in an atmosphere with a lot of moisture and oil in the air, and "PX Belt Water-Proof Type" in an atmosphere with a lot of moisture.

Generally, it is as follows.

1. ①Impact noise generated when the bottom of the synchronous belt collides with the top of the belt sprocket.
2. ②Synchronous belt string vibration noise
3. ③Friction noise generated when the tooth of synchronous belt engage with the tooth groove of belt sprocket while rubbing against each other
4. ④Friction noise generated when the side face of synchronous belt and the guide flange of belt sprocket rub against each other
5. ⑤Air discharge noise generated by discharging air from the tooth groove of belt sprocket when synchronous belt and belt sprocket are engaged

1. ①Change natural frequency of synchronous belt by changing installation tension, belt sprocket revolution speeds, belt length, belt width, number of belt sprocket teeth, etc.
2. ②Change to a high strength synchronous belt and narrows belt width
3. ③Narrows belt width and change to multi-strand
4. ④Adjust the alignment of belt sprocket so that synchronous belt does not touch guide flange.

Compliant with RoHS Directive.

Maximum is approximately 98%.

[Appearance features ]

Breakage is parallel to the belt teeth. The cords are also short and cut.

[Possible causes ]

1. ①The cords were broken due to excessive bending during storage and assembly.
2. ②The cords were broken because the belt sprocket diameter was too small.

[Action ]

1. ①Be careful when storing and assembling, and do not bend it excessively. Do not bend to a diameter less than 4 times the pitch.
2. ②Check if diameter of belt sprocket and idler is appropriate, and change it to the appropriate diameter if it is too small. Check the belt sprocket diameter in the transmission capacity table, and the idler diameter in the table below.

• Inside idler ......A timing belt sprocket having the number of teeth greater than the minimum number of teeth of belt sprocket in the following table.
• Outside idler ......A flat belt sprocket that is greater than 1.2 times the pitch circle diameter of the belt sprocket in the following table and does not have a crown.

■Minimum number of teeth of belt sprocket for selection of an idler

Types	Speed r/min
	Up to and incl. 900	Over 900, up to and incl. 1200	Over 1200, up to and incl. 1800	Over 1800, up to Type and incl. 3600
P2M	16	16	18	20
P3M・UP3M	14	14	16	18
P5M・UP5M	18	20	24	28
P8M・UP8M	24	26	26	28
P14M・UP14M	28	28	28	34

Note) For revolutions above 3600 r/min, refer to the Standard Transmission Capacity Table.

Inside idler

Outside idler

[Appearance features ]

• Tooth fabric is fluffy, whitish and discolored, and texture is unclear.
• Tooth fabric is worn and rubber is exposed.
• Belt teeth become thinner.
• Tooth fabric on the bottom of belt tooth is worn and cord is exposed.

[Possible causes ]

1. ①Overloaded.
2. ②Too high installation tension.
3. ③Insufficient installation tension.
4. ④Insufficient synchronous belt capacity.
5. ⑤Incorrect belt sprocket tooth profile or incorrect dimensions of the tooth part.
6. ⑥Use in dusty atmosphere.

[Action ]

1. ①Check motor specifications, inertia of driven unit, and operation conditions to eliminate the cause of overload, or increase the size of synchronous belt / belt sprocket.
2. ②Adjust to the proper installation tension.
3. ③Adjust to the proper installation tension.
4. ④Check the operation conditions and select the optimum size synchronous belt / belt sprocket.
5. ⑤Replace with a belt sprocket of the correct tooth profile and dimensions.
6. ⑥Prevent dust from adhering to synchronous belt and belt sprocket by improving atmosphere and installing a cover.

[Possible causes ]

1. ①Overloaded (shock load).
2. ②Insufficient installation tension.
3. ③Insufficient number of meshed teeth with the belt sprocket.
4. ④Insufficient rigidity of frame.

[Action ]

1. ①Eliminate the cause of shock load or install a shock damping mechanism. Or increase the size of the synchronous belt.
2. ②Adjust to the proper installation tension.
3. ③Either increase the number of belt sprocket teeth or increase the number of meshed teeth by using an idler.
4. ④Increase the rigidity of frame.

[Appearance features ]

• Cracks occur at the base of belt teeth.
• Belt teeth are missing.

[Possible causes ]

Same as the estimated cause of "Q30 Wear of synchronous belt teeth" and "Q31 Synchronous belt tooth jumping". As a consequence of these situations, it leads to shear failure.

[Action ]

Refer to the same measures as for "Q30 Wear of synchronous belt teeth" and "Q31 Synchronous belt tooth jumping".

[Appearance features ]

• The corners on the side faces are rounded.
• The rubber on the side face is in a state of being peeled off.
• The cord is frayed and exposed.

[Possible causes ]

1. ①Poor parallelism between shafts.
2. ②Poor belt sprocket alignment.
3. ③Insufficient rigidity of frame.
4. ④Deformation of the guide flange of belt sprocket.

[Action ]

1. ①Align the parallelism of shafts correctly.
2. ②Align the belt sprocket to the correct position.

   Belt Size	All
   Belt width mm	Up to and incl. 30	30～50	50～100	Over 100
   Allowable degree of parallelization	Up to and incl. 5/1000	4/1000 or less	3/1000 or less	2/1000 or less
   θ min	Up to and incl. 17	Up to and incl. 13	Up to and incl. 10	Up to and incl. 6

   
   [Click to enlarge ]

   ■How to adjust the belt sprocket

   As shown in the diagram, apply the straight edge to the end face of the standard belt sprocket. Make the other belt sprocket contact with straight edge on all faces (to make ε=0), so that the belt sprockets can be aligned in the correct position.

   Parallelism of shafts can be obtained simultaneously by setting δ in the diagram below the limit.

   
   [Click to enlarge ]

3. ③Increase the rigidity of frame.
4. ④Replace with a new one.

[Appearance features ]

• There are vertical scratches on the belt teeth.

[Possible causes ]

1. ①Running beyond the edge of belt sprocket.
2. ②Riding up on the guide flange of belt sprocket.

[Action ]

1. ①Parallelism of shafts or position of belt sprocket is incorrect, so adjust it to the correct position.
2. ②If parallelism of shafts or position of belt sprocket is incorrect, adjust it to the correct position.

   Check an installation tension, and adjust it to the adequate installation tension if it is insufficient.

[Appearance features ]

• It is partially cut.
• Scratches may be observed on the tooth surface other than the cut part.

[Possible causes ]

1. ①Riding up on the guide flange of belt sprocket.
2. ②Stuck foreign matter.

[Action ]

1. ①If parallelism of shafts or position of belt sprocket is incorrect, adjust it to the correct position.

   Check an installation tension, and adjust it to the adequate installation tension if it is insufficient.

3. ②Improve environment or install a cover to prevent foreign matter from adhering to synchronous belt / belt sprocket.

[Appearance features ]

• Rubber is swollen.

[Possible causes ]

• Rubber absorbed oil and water adhering to synchronous belt.

[Action ]

• Improve environment or install a cover to prevent oil and moisture from adhering to synchronous belt.
• Replace with "Ultra PX Belt Oil-Proof Type" may be possible. Please consider it.

[Possible causes ]

Proximity of shafts each other due to shafts movement.

[Action ]

Securely fix the shaft.

[Appearance features ]

• Softened rubber is adhered to the back of synchronous belt.
• Synchronous belt's rubber is sticky or softened.

[Possible causes ]

1. ①Oil adhered to synchronous belt, and rubber absorbed it.
2. ②Use in high temperature 。
3. ③Poor rotation of outside idler

[Action ]

1. ①Improve environment or install a cover to prevent oil from adhering to synchronous belt.

   Replace with "Ultra PX Belt Oil-Proof Type" may be possible. Please consider it.

2. ②Lower atmospheric temperature to 80℃ or less.
3. ③Adjust the idler to rotate smoothly. Example: Reduce the inertia of idler, increase the bearing size.

[Appearance features ]

• There is a dent on the back which is parallel to the edge.
• Mark on the back has disappeared or is about to disappear.

[Possible causes ]

1. ①Poor alignment of outside idler shaft.
2. ②Poor rotation of outside idler.

[Action ]

1. ①Parallelism of shaft is incorrect. Adjust it to the correct position.
2. ②Adjust the idler to rotate smoothly. Example: Reduce the inertia of idler, increase the bearing size.

[Appearance features ]

• There are cracks on the back of synchronous belt parallel to the teeth.

[Possible causes ]

1. ①Belt sprocket or idler diameter being used is too small.
2. ②Operating atmosphere temperature is too high or too low.

[Action ]

1. ①Check if diameter of belt sprocket and idler is appropriate, and change it to the appropriate diameter if it is too small.

   (Check the belt sprocket diameter in the transmission capacity table, and the idler diameter in the table below. )

   • Inside idler ......A timing belt sprocket having the number of teeth greater than the minimum number of teeth of belt sprocket in the following table.
   • Outside idler ......A flat belt sprocket that is greater than 1.2 times the pitch circle diameter of the belt sprocket in the following table and does not have a crown.

   ■Minimum number of teeth of belt sprocket for selection of an idler

   Types	Speed r/min
   	Up to and incl. 900	Over 900, up to and incl. 1200	Over 1200, up to and incl. 1800	Over 1800, up to Type and incl. 3600
   P2M	16	16	18	20
   P3M・UP3M	14	14	16	18
   P5M・UP5M	18	20	24	28
   P8M・UP8M	24	26	26	28
   P14M・UP14M	28	28	28	34

   Note) For revolutions above 3600 r/min, refer to the Standard Transmission Capacity Table.

   

   Inside idler

   

   Outside idler

2. ②Improve atmosphere temperature to -15℃ to 80℃ where synchronous belt can be used.

[Appearance features ]

• Area where synchronous belt is engaged is worn, and there is a step between area not engaged.
• Tooth surface is rough.

[Possible causes ]

1. ①Inappropriate belt sprocket material.
2. ②In a dusty atmosphere, synchronous belts and belt sprockets were used with abrasive dust adhering on them.
3. ③Installation tension of synchronous belt is too high.

[Action ]

1. ①Change to a harder material, apply tooth surface hardening or surface treatment to improve wear resistance.
2. ②Improve usage atmosphere or install a cover to prevent dust from adhering.
3. ③Adjust to the proper installation tension.

30 to 600Hz for BDTM101 and 10 to 5000Hz for BDTM201 as a frequency of synchronous belt.
If the measuring span is too short or too long layout, vibration frequency may be out of the measurable range and measurement may not be possible.

We are lending out demo machines. Please contact us.

We accept it for a fee. Please contact us.

Set the calibration cycle based on customer rules and judgment.

High-strength aluminum is treated with white anodized aluminum.

We will examine whether it can be manufactured, so please contact us with a drawing.