Qu'est-ce que le pas du pignon ?

Sprocket pitch is the distance between the centers of two adjacent chain pins (or rollers). For a drive system to function correctly, the sprocket pitch must exactly match the chain pitch to ensure smooth engagement. Typically measured in inches, a larger pitch signifies larger gear teeth and a higher load capacity. You can identify your sprocket pitch by checking the manufacturer’s stamp (e.g., “40” or “520”) on the chain or by using a caliper to measure the precise center-to-center distance between two pins.

Pitch Matching Is Important In The Drivetrain

The synchronicity between the sprocket and its supporting chain is the cornerstone of mechanical power transmission. When we talk about “pitch”, we are essentially talking about the geometry, which determines whether the chain rollers can fit perfectly into the tooth groove (that is, the tooth root) of the sprocket.

If there is even a slight deviation between the sprocket pitch and the chain pitch, the whole system will collapse quickly. There are usually the following kinds of trouble:

• Accelerated wear: The chain cannot sit deep in the tooth groove, but tends to climb on the tooth tip, which will cause a surge in friction.
• Mechanical failure: pitch mismatch will cause the chain to jump teeth under load or even collapse directly.
• Noise and vibration: A slightly knowledgeable person can tell if the pitch is right by listening to the sound. The mismatched running sound is very harsh, and this high-frequency vibration will directly damage the life of the bearing and motor.

Correlation Of Pitch Size With Load Capacity

The pitch is a direct indicator of the physical size and strength of the sprocket. In the field of power transmission, size often directly equals capacity.

• Small pitch: More common in precision instruments or high-speed, low-torque scenarios (such as bicycles or small electronic devices). This specification allows for a more compact design, but with a lower upper tensile strength limit.
• Large pitch: Common in heavy industrial machinery, conveyors and motorcycles. A large pitch means that the sprocket teeth are thicker and the chain pins are thicker. This configuration is designed to resist high torque and heavy load, and the metal parts are not prone to plastic deformation under heavy pressure.

Interpreting Vendor Stones (ANSI And ISO)

Most professional-grade sprockets and chains are marked with a specific code, allowing you to see the pitch at a glance. Mastering these digital laws is the fastest way to identify hardware.

For the standard ANSI (American National Standards Institute) chain, there is a so-called “8-point principle”: the first number represents a multiple of 1/8 inch.

• 40 Chain/Sprocket: The pitch is 4/8 inch, or 1/2 inch.
• 60 chain/sprocket: The pitch is 6/8 inch, which is 3/4 inch.
• 80 Chain/Sprocket: The pitch is 8/8 inch, which is 1 inch.

In the field of motorcycles, common codes such as 520 or 530. The beginning number “5” represents a pitch of 5/8 inch, while the following two digits represent the width between the inner link plates.

How To Accurately Measure Sprocket Pitch

If the equipment has been running for too long and the manufacturer’s stamp has been worn and blurred, it must rely on manual measurement. At this time, accuracy is the lifeblood, because even an error of a few tenths of a millimeter may make you choose the wrong standard when ordering spare parts.

Accurate Measurement With Calipers:

In order to get an accurate reading, you can follow these steps:

• Pin-to-pin measurement: Place the tip of the caliper at the exact center of one pin and measure the distance to the center of the next adjacent pin.
• “2.1” method: If it is difficult to find the center of the pin, you can measure the front edge of one pin to the front edge of the next pin. This distance is exactly the same as the center distance, but it is often easier to locate in operation.
• Data cross-matching: After obtaining a decimal measurement (such as 0.50 “), it is converted to a fraction (1/2”) so that it can be easily matched to the standard size library.

Auteur : Paul
“Hi, I’m a mechanical systems specialist with over a decade of experience in power transmission and industrial maintenance. Throughout my career, I’ve handled countless chain-driven systems, from heavy-duty industrial conveyors to high-performance motorcycles. I’m passionate about breaking down complex mechanical concepts—like sprocket geometry and pitch alignment—to help engineers and technicians optimize their machinery for peak performance and longevity.”