HTD/Powergrip GT Pitch Pulleys – Pulley School – Class 2: The Basics

The HTD and PowerGrip GT pitch pulleys are based in the metric system. The tooth profile of these common pulleys is curvilinear, and looks like: htd timing pulley tooth profile

Standard/Stock Part # Configuration:


This part number is comprised of 7 coded sections:

1. (15) 2. (5M) 3. (15) 4. (-) 5. (6F) 6. (A) 7. (3)

1. Number of teeth in the pulley:

Can be 1-3 digits in length, and will always be a direct reflection of the number of teeth on the pulley. Example pulley above would have 20 teeth.

2. Pitch of the pulley:

Pitch refers to the distance from the center of a pulley tooth to the center of the next tooth. Fore these curvilinear pitches, B&B uses an abbreviated code to express the pitch for part numbering purposes. Common pitches, and their codes:

2P/2MR = 2mm PowerGrip GT

3P/3MR = 3mm PowerGrip GT

5P/5MR/5MGT = 5mm PowerGrip GT

3M = 3mm HTD

5M = 5mm HTD

8M = 8mm HTD

3. Belt Width:

This code indicates the width of the toothed section of a timing pulley, and directly corresponds to the width of the belt intended to run on the pulley. When measuring the toothed section of a pulley to determine its code, remember the width of the toothed section will be slightly larger than the belt intended to run on that section.

Common belt width codes for HTD/PGGT pitch pulleys:

06 – 6mm belt

09 – 9mm belt

15 – 15mm belt

20 – 20mm belt

25 – 25mm belt

30 – 30mm belt

4. Inch/Metric Designation

This code component has only two possibilities: “-” or “M”. This code component will clarify our interpretation of the final character in our part number. When the “-” character is used, the final part number section will be interpreted using the inch system of measurement. When the “M” character is used, the final part number section will be interpreted using the metric system. We will go into further detail shortley, when discussing the final coded section.

5. Pulley Appearance

This section of code will help you determine the physical appearance of the pulley, and the components used to assemble the pulley. These codes will be used throughout B&B’s part numbering system.

Standard pulley appearnce codes are:

  6F: With hub, with flanges.

6C: Typically for very small pulleys. These pulleys have a flange on one side and a hub that works as a flange on the other side.

6:  With hub, no flanges.

  6W: Typically for larger pulleys. Pulley has a hub, no flanges, and the body of the pulley has material removed to reduce weight.

3F: Without hub, with flanges.

3: Without hub, without flanges. Rarely used; few standard offerings.

6. Pulley Material:

This section of code indicates the material from which the pulley was made. The vast majority of our standard product line (using this type of part number) will have one of two codes:

A = Aluminum

S = Steel

Seldom used codes:

P = Plastic

I = Cast Iron

SS = Stainless Steel


7. Bore Size:

The final section of code in our part number will indicate the bore size of the pulley. As we noted earlier, the fourth section of code will have relevance in determining how this final section is interpreted. If the fourth section is a “-”, we will use a code to indicate our bore size in inches. If the fourth section is a “M” we will use a code to indicate our bore size in millimeters. The inch codes are incrementally issued based on common bore sizes, from smallest to largest. The metric bores are typically a direct reflection of the bore size in millimeters.


1 = .125″ = 1/8″

2 = .1875″ = 3/16″

3 = .250″ = 1/4″

4 = .3125″ = 5/16″

5 = .375″ = 3/8″

6 = .500″ = 1/2″

7 = .625″ = 5/8″

8 = .750″ = 3/4″

9 = .875″ = 7/8″

10 = 1.00″ = 1″


3 = 3MM

4 = 4MM

5 = 5MM

6 = 6MM

8 = 8MM

10 = 10MM

12 = 12MM

15 = 15MM


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