EN
In the realm of precise mechanical power transmission, the combination of timing belts and pulleys is a core component for transmitting motion and power. Correct selection is paramount, determining not only a system's efficiency, accuracy, and noise levels but also its long-term reliability and total cost of ownership. A mismatched choice can lead to tooth jumping, premature wear, energy loss, and even unplanned downtime.
This guide provides a systematic approach to help engineers and maintenance personnel select the most suitable timing belt and pulley for their specific applications.
Step 1: Define Core Application Parameters
Successful selection begins with a clear definition of requirements. Before consulting product catalogs, confirm these key details:
Power & Torque: How much power must the system transmit? What is the peak torque?
Speed: What are the rotational speeds (RPM) of the driver and driven shafts? What is the required gear ratio?
Spatial Constraints: Do installation space limitations dictate pulley diameters or center distance?
Environmental Factors: Will the system be exposed to extreme temperatures, oils, chemicals, dust, or moisture?
Precision & Noise Requirements: Does the application demand high positional accuracy? Are there strict requirements for operational noise?
Step 2: Select the Timing Belt Type & Tooth Profile
Belt performance is primarily determined by its tooth profile and material.
Determine the Tooth Profile:
Trapezoidal (e.g., MXL, XL, L, H): Classic design, suitable for medium loads and general industrial applications.
Curvilinear (e.g., HTD, STD, GT): The modern mainstream choice. The rounded tooth root provides superior stress distribution, enabling higher torque transmission, quieter operation, and longer life. HTD (High Torque Drive) and the more advanced GT (Gates GT®) series are widely used in automation, servo systems, etc.
Special Profiles (e.g., AT, T, PolyChain®): Designed for extremely high torque, heavy loads, or special synchronization requirements.
General Rule: For modern high-performance applications, especially servo drives, curvilinear profiles are recommended.
Choose the Belt Material:
Polyurethane Body + Steel/Aramid Cords: Most common. Polyurethane is wear-resistant, flexible, and resistant to many substances. Suitable for most industrial environments.
Rubber Body + Fiberglass Cords: Often used in heavy-duty drives, offering excellent impact and fatigue resistance.
Teflon-Coated or Full PTFE Belts: Used in food, pharmaceutical, or applications requiring anti-adhesion, easy cleaning, or resistance to strong chemicals.
Step 3: Select and Match the Timing Pulley
Pulleys are not standalone components; they must precisely match the belt.
Tooth Profile & Pitch Must Match: Select a pulley with the exact same tooth profile and pitch (e.g., 5M, 8M, GT2-3mm) as the timing belt. This is a non-negotiable principle.
Determine the Number of Teeth (Diameter):
Number of Teeth on the Small Pulley: This is critical. Too few teeth increase bending fatigue and reduce belt life. Consult the manufacturer's minimum recommended number of teeth table, based on transmitted torque and belt speed.
Gear Ratio & Center Distance: Determine the tooth combination of the large and small pulleys based on the gear ratio, and verify feasibility within the available installation space (center distance).
Specify the Pulley:
Material: Common options are aluminum (lightweight, high-speed), steel (high rigidity, heavy-duty), or engineered plastics (corrosion-resistant, quiet).
Flange Type: Standard, flanged (to prevent tracking off), or with crowned teeth.
Bore & Mounting: Determine the bore type (keyway, clamp bushing, taper-lock, etc.) and size to ensure a secure connection to the shaft.
Step 4: Calculation & Finalization
Utilize the manufacturer's online selection software or engineering manuals. Input all parameters (power, speed, ratio, center distance, service factor, etc.) for detailed calculation. This will finalize:
The exact timing belt model and width.
The final pulley tooth count and model.
The recommended initial installation tension.
Avoid Common Mistakes
Selecting based solely on experience or appearance.
Ignoring environmental impacts on material choice.
Choosing non-standard or low-precision pulleys to save cost, accelerating belt wear.
Failing to account for proper maintenance tensioning space.
The Value of Professional Support
For critical or complex applications, consulting a power transmission specialist is strongly advised. A professional supplier can offer comprehensive support—from selection calculations and sample testing to installation guidance—ensuring optimal system performance from day one.
For further information or to access free selection support, please contact us.
