How To Measure & Identify V-Belt Pulleys

One of the ever-growing and most widely used product types in the power transmission and automotive industries is the V-belt pulley, also known as the “sheave.” A V-belt pulley is an attachment that transfers energy between axles with the help of a V-belt. However, to keep this important pair of devices functioning properly, one must secure the appropriate V-belt pulley replacement when an older one gets worn down. To do this, you need to know the size, dimensions, and type of your V-belt pulley so that the replacement will operate properly. Learning how to measure a V-belt pulley’s size and calculate its dimensions is a simple task; however, properly identifying a V-belt pulley type can be a complex process. V-belt pulleys come in a multitude of different styles and options, including A-section, B-section, C-section, D-section, 3V-section, 5V-section, 8V-section, variable pitch, double groove, and metric pulleys. We stock over 8,000 SKUs of different V-belt pulleys alone!

If you are looking for more details, kindly visit our website.

How To Measure A V-Belt Pulley

Please Note: For the below illustrations we use a standard single-groove V-belt pulley.

Step 1:

First, measure the outside diameter (OD) of the pulley.

Step 2:

Next, measure the pitch diameter (PD). This measurement represents the diameter of the belt itself as it rides in the pulley. This step is not necessary if you already know your V-belt size or if the pulley and belt are significantly worn.

Step 3:

Measure the wall thickness of the pulley.

Step 4:

Measure the overall width of the belt housing, where the belt actually rides in the pulley.

Step 5:

If the pulley has a hub extending past the "belt housing" width it is typically a best practice to measure the extension of the hub.

Step 6:

The final measurement is the complete overall width of the pulley. This will in most cases designate the belt-type or series used.

How To Identify a V-Belt Pulley

The easiest way to identify a V-belt pulley is by finding the part number or identification components on the pulley itself. Different brands, as well as different pulley types, have various ways they may display these numbers.

Style 1:

Probably the most common style for medium and smaller pulleys is when the number is stamped into the pulley before it is painted or phosphated. This can make it hard to identify the numbers and letters in most circumstances.

Style 2:

Another style is when the part number is stamped in the casting itself.

Style 3:

Another style involves placing different identification characters on different spokes. For example, in the image, we see "5-5V" on one spoke, "1870" on the second spoke, and "E" on the third:

5-5V: 5-groove, 5V belt size;

1870: Diameter;

E: Bushing used.

The catalog part number would be 55V1870E.

Style 4:

On some pulleys, the part number is actually painted onto it. The issue with this is that over time, it can rub off, making it more difficult to identify the pulley.

Alternatively:
Alternatively, if your part number is not distinguishable, follow steps 1-6 above to measure the pulley. Then, determine the style of pulley you have based on the photos below.

Note: If you have a fixed bore pulley please advise of the bore inside diameter.

Lastly, we'll need to know how many grooves are in your pulley; this, along with the overall width, will confirm the belt type you are using.

Check Pulley Grooves For Wear With This Tool

Here’s how you can spin your driven pulley faster or slower.

When speaking of rotational speeds of motor-driven pulleys, you’re probably asking these types of questions: 

• What’s the difference between big and small pulleys in terms of speed? 
• Does a bigger drive pulley increase speed? 
• Does a bigger drive pulley increase torque? 
• How do I make my driven pulley spin faster or slower? 
• How do I change the (rotational) speed of my pulley? 
• How do I increase my pulley speed? 
• Will a smaller pulley spin faster or slower? 
• Which pulley will turn faster or slower? 

We’ll attempt to answer them given these assumptions: 

• You won’t be replacing your electric motor. Of course, you can change the speed of the pulleys by using a motor with a different speed rating, but we’re assuming you don’t want to do this. 
• You’ll be using the same drive pulley (the one attached to the motor shaft). Some call this the driver pulley. 
• You’re only interested in changing the speed of your driven pulley (the one driven by the belt). There can be more than one driven pulley (and therefore, more than one belt) in a more complex system.

 

 

 

 

 

Diameter ratio of drive and driven pulleys 

Without getting too technical, you just change your driven pulley to one with a bigger or smaller diameter relative to your driver pulley. 

• The bigger your driven pulley (vs the driver), the slower it will turn but the more torque it will produce. 
• The smaller your driven pulley (vs the driver), the faster it will turn but the less torque it will produce.  

Put simply: 

• To speed up a driven pulley (and achieve less torque) it should be smaller than the drive pulley. 
• To slow down a driven pulley (and achieve more torque) it should be larger than the drive pulley. 

Here’s how you can calculate the exact values: 

Values: 

• D1:

  Diameter of the drive(r) pulley that is attached to the motor shaft 

• V1:

  Velocity/Speed of the drive(r) pulley (We'll just use 1000 rpm in the table below for simplicity.) 

• D2:

  Diameter of the driven pulley 

• V2:

  Velocity/Speed of the driven pulley 

To answer how fast your driven pulley (V2) will be: 

• V2

  =

  V1

  (

  D1

  /

  D2

  ) 

To answer the size of your driven pulley (D2): 

• D2

  =

  D1

  (

  V1

  /

  V2

  ) 

Here are some pre-calculated values* for your convenience: 

D1

V1 (rpm)

If you want to learn more, please visit our website Joyroll.

D2

V2 (rpm)

5

1000

10

500

10

1000

10

1000

10

1000

5

2000

10

1000

20

500

20

1000

20

1000

20

1000

10

2000

*The values of D1 and D2 must have the same unit (ie both in inches, or both in millimeters). Convert one to the other, if you must.

*1 inch = 25.4 millimeters 

It is worth noting that the RPM is a theoretical, calculated value, just as the rated RPM of your motor is. The exact RPM you achieve will, naturally, depend on your specific set up. 

To make your life easier, here’s a calculator courtesy of Engineering Toolbox. 

• Pulley 1 is the drive(r) pulley connected to your motor. 
• Pulley 2 is the driven pulley. 

The values for pulleys 3 and 4 are optional. Use those fields if you have more than one driven pulley, otherwise just leave them blank. 

Shop for pulleys now. 

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