Types Of Synchronous Belt Profiles and Nomenclature

Timing Belt

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Synchronous belts, also known as timing belts, resemble a flat belt with evenly spaced teeth that are perpendicular to the axis of the belt.

The belt teeth are designed to mash with pulley (sprocket) teeth, similar to chains. Timing belts do not rely on friction to transmit torque; instead they rely on positive engagement of belt teeth with the teeth on sprocket. This results in very little relative movement between the belt and the sprocket. Timing belts should be used where exact synchronization between driver and driven shafts is required. Timing belts are also available in dual sided configuration. Dual sided timing belts have teeth on both sides of the belt. 

First synchronous belt drives were seen in the early 1940s. The tooth profile was simple trapezoidal design. This design is still in use today. It is available in 6 standard pitches in the inch system. Bellow is the letter designations for these pitches. 

 

  • MXL            Mini Extra Light                   0.080” 

  • XL               Extra Light                           0.200” 

  • L                 Light                                     0.375”

  • H                Heavy                                    0.500”  

  • XH              Extra Heavy                          0.875”

  • XXH            Double Extra Heavy            1.250”

 

 

The part numbers for trapezoidal belts are written in the following format

 

250XL050

250 means 25” Length, XL 0.200” pitch, 0.50” wide.

 

Nowadays, there are three common types of synchronous belts, based on their curvilinear profiles: H-type, S-type, R-type. 

 

H-TYPE 

 

The H-type tooth profile is referred to as HTD. It has a round tooth profile, and its shape is defined by a group of radii centered a specific distance from the pitch line of the belt. 

It is available in 3mm, 5mm, 8mm, 14mm and 20 mm pitches in a variety of widths and lengths. 

Part number typically has the format shown below 

 

540-H8M-20 

 

540 means 540mm pitch length, H8M 8mm pitch, H-type tooth profile, 20 for 20mm belt width  

A dual-sided version of this belt has following part number: 

 

540-DH8M-20 

 

S-TYPE 

 

The S-type tooth profile is referred to as STPD.  

It is available in 3mm, 4,5mm, 5mm, 8mm and 14mm pitches in a variety of widths and lengths. 

Part number typically has the format shown below 

 

80-S8M-380 

 

80 means 8mm belt width, S8M stands for 8mm pitch, S-type tooth profile, 380 is pitch length in mm. 

A dual-sided version of this belt has following part number: 

 

80DS8M380

 

Where ‘D’ indicates ‘dual-sided’ 

 

R-TYPE 

 

The R-type synchronous belt is a deep profile parabolic tooth design that can be used in R-type. 

It is available in 5mm, 8mm, 14mm and 20mm pitches in a variety of widths and lengths, in single side and dual side configuration. 

Part number typically has the format shown below 

 

185-3M-20 

 

185 means 185mm pitch length, 3M stands for 3mm pitch, 20 is belt width in mm.

A dual-sided version of this belt has following part number: 

 

D185-3M-20 

 

The R-type is used in the automotive industry as cam timing drives, replacing chain. 

Timing belts are much lighter than chain, require less maintenance and do not need lubrication.

 

Feel free to Contact Us if you have any questions, need more information or if you are interested in purchasing a timing belt.

Check out our Timing-Belt selection

Brands HVH offers: BandoContinental ContitechMitsuboshi Belting

 


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Vladimir Harutyunyan

Vladimir Harutyunyan is the founder of HVH Industrial. He has masters degree in mechanical engineering and over 10 years of experiance in mechanical power transmission field. 

Feel free to connect with Vlad on Linkedin: https://www.linkedin.com/in/vladharut



image

Vladimir Harutyunyan

Vladimir Harutyunyan is the founder of HVH Industrial ...

Feel free to connect with Vlad on Linkedin: https://www.linkedin.com/in/vladharut


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