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Timing Belt Identification and Replacement

Downloadable/printable Timing Belt Identification and Replacement (.pdf)

The first step in identifying which timing belt that you have is to look for identifying numbers and/or letters marked on the timing belt. These numbers indicate a standard trade size and will help in identifying the specifics of the cog belt. Also, by being able to identify the manufacturer and/or trade name on the timing belt will assist in the identification process. Common synchronous belt manufacturers include:

Bando www.bandousa.com
Brecoflex www.brecoflex.com
Carlisle Power Transmission Products www.cptbelts.com
Continental ContiTech www.contitech.de
Elatech www.elatech.com
F.N. Shephard, Co. www.fnsheppard.com
Forbo Siegling www.forbo-siegling.com
Gates www.gates.com
Goodyear Engineered Products (Veyance) www.goodyearep.com
Habasit www.habasitabt.com
Jason www.jasonindustrial.com
Mectrol (Gates) www.gatesmectrol.com
Megadyne www.megadyne.it
Mitsuboshi Belting, Ltd. www.mitsuboshi.co.jp
Optibelt Power Transmission www.optibelt.com
U.S.A. Drives, Inc. www.usadrivesinc.com

Secondly, if there is no trade size indicated on the timing belt do the following:

  • Measure the width of the timing belt
  • Note the construction of the timing belt. Rubber construction is extremely flexible while a polyurethane construction is plastic like and has little flexibility
  • Measure the pitch (see diagram). This is the distance in millimeters (mm) and/or inches between the center of the crown of one tooth and the center of the crown of the tooth adjacent to it.Timing Belt Tooth Profile & Pitch

Downloadable/printable Timing Belt Tooth Profiles and Pitches (.pdf)

CTD

 

 

 

Pitch

Timing Belt Tooth Profile / Pitch

Inches

Metric

CTD

 C8M / CTD

 8mm

0.315"

8mm

 C14M / CTD

 14mm

0.551"

14mm

HTD

 

 

 

Pitch

Timing Belt Tooth Profile / Pitch

Inches

Metric

HTD

 3M / HTD

 3mm

0.118"

3mm

 5M / HTD

 5mm

0.197"

5mm

 8M / HTD

 8mm

0.315"

8mm

 14M / HTD

 14mm

0.551"

14mm

 20M / HTD

 20mm

0.787"

20mm

PolyChain GT

 

 

 

Pitch

Timing Belt Tooth Profile / Pitch

Inches

Metric

PolyChain GT

 5M / PCGT

 5mm

0.197"

5mm

 8M / PCGT

 8mm

0.315"

8mm

 14M / PCGT

 14mm

0.551"

14mm

PolyChain GT HTD

 

 

 

Pitch

Timing Belt Tooth Profile / Pitch

Inches

Metric

PolyChain GT HTD

 14M / PCGT HTD

 14mm

0.551"

14mm

PolyChain GT2

 

 

 

Pitch

Timing Belt Tooth Profile / Pitch

Inches

Metric

PolyChain GT2

 8M / PCGT2

 8mm

0.315"

8mm

 14M / PCGT2

 14mm

0.551"

14mm

PolyGrip GT2

 

 

 

Pitch

Timing Belt Tooth Profile / Pitch

Inches

Metric

PowerGrip GT2

 2MR / PGGT2

 2mm

0.079"

2mm

 3MR / PGGT2

 3mm

0.118"

3mm

 5MR / PGGT2

 5mm

0.197"

5mm

 8M / PGGT2

 8mm

0.315"

8mm

 14M / PGGT2

 14mm

0.551"

14mm

 20M / PGGT2

 14mm

0.787"

20mm

RPP

 

Pitch

Timing Belt Tooth Profile / Pitch

Inches

Metric

RPP

 5M / RPP

 5mm

0.197"

5mm

 8M / RPP

 8mm

0.315"

8mm

 14M / RPP

 14mm

0.551"

14mm

 20M / RPP

 20mm

0.787"

20mm

STD

 

 

Pitch

Timing Belt Tooth Profile / Pitch

Inches

Metric

STD

 S8M / STD

 8mm

0.315"

8mm

Trapezoidal (Inch Pitch)

 

 

Pitch

Timing Belt Tooth Profile / Pitch

Inches

Metric

Trapezoidal (Inch Pitch)

 2/25" MXL

 0.080"

0.080"

2.032mm

 40 D.P.

 0.0816"

0.0816"

2.07mm

 1/5" XL

 0.200"

0.200"

5.08mm

 3/8" L

 0.375"

0.375"

9.525mm

 1/2" H

 0.500"

0.500"

12.7mm

 7/8" XH

 0.875"

0.875"

22.23mm

 1-1/4" XXH

 1.250"

1.250"

31.75mm

Trapezoidal (Metric Pitch)

 

 

Pitch

Timing Belt Tooth Profile / Pitch

Inches

Metric

Trapezoidal (Metric Pitch)

 T2.5

 2.5mm 

0.098"

2.5mm

 T5

 5mm

0.197"

5mm

 T10

 10mm

0.394"

10mm

 T20

 20mm

0.787"

20mm

Trapezoidal (Metric Pitch)

 

 

Pitch

Timing Belt Tooth Profile / Pitch

Inches

Metric

Trapezoidal (Metric Pitch)

 AT5

 5mm

0.197"

5mm

 AT10

 10mm

0.394"

10mm

 AT20

 20mm

0.787"

20mm

Note:  Timing Belt Tooth Profile Abbreviations

 

 

 

CTD

 ContiTech - Conti Torque Drive

 

 

HTD

 High Torque Drive

 

 

PGGT

 Gates - PowerGrip GT

 

 

PGGT2

 Gates - PowerGrip GT2

 

 

PCGT

 Gates - PolyChain GT

 

 

PCGT HTD

 Gates - PolyChain GT HTD

 

 

PCGT2

 Gates - PolyChain GT2

 

 

RPP

 Carlisle - Reinforced Parabolic Profile

 

STD

 Super Torque Drive

 

 

Trapezoidal

 Trapezoidal

 

 

  • Note the shape of the timing belt pulley teeth (tooth profile); if the valley between the teeth is curved than it is an HTD style timing belt. If the valley between the teeth is flat than it is and PolyChain GT style timing belt. You should also look for identifying numbers and/or letters on the pulleys themselves to help in the timing belt tooth profile identification.
  • CTD Timing Belt Tooth Profile
  • PolyChain GT Timing Belt Tooth Profile
  • PolyChain GT Timing Belt Tooth Profile
  • PowerGrip GT2 Timing Belt Tooth Profile
  • RPP Timing Belt Tooth Profile
  • STD Timing Belt Tooth Profile
  • Trapezoidal Timing Belt Tooth Profile
  • Count the number of teeth on the timing belt. I suggest marking one tooth on the timing belt with some sort of identification so that you have a starting point for the tooth count. You can also measure the length of the timing belt from end to end if the belt is broken. If the timing belt is in place measure the circumference of the timing belt (distance around the outside edge of the timing belt)

From these pieces of information a replacement timing belt can be identified.

Lastly, if you are changing any of the timing belt pulleys in the power transmission drive than the timing belt length is more than likely to change also. The following information will be needed to determine the correct timing belt length

  • Center to center distance between the shaft the driver pulley is fixed to and the shaft the driven pulley is fixed to. This measurement is taken from the center of the shafts. There should be two (2) measurements for this since the majority of timing belt drives has a means in place for tensioning the belts. The two distances required will have one of the shafts in the all the way forward position and the other in the all the way backward position.
    • Center to center distance all the way FORWARD
    • Center to center distance all the way BACKWARD
  • Count the number of teeth on both timing belt pulleys. I suggest marking one tooth on the timing belt pulleys with some sort of identification so that you have a starting point for the tooth count

From these pieces of information a replacement timing belt can be identified.

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