Belt-driven linear module load capacity is the maximum payload a belt-driven module can carry at a given speed, stroke, and moment load without exceeding belt tension or rail limits. In a multi-axis setup, each axis carries its own payload plus the mass of the axes mounted downstream. Calculate the load case for the axis closest to the base first, because it moves the most mass. Add the moving mass of every downstream axis to the payload, then recalculate belt force and moment for that axis. A gantry or XY configuration can therefore reduce the rated payload of the lower axis well below its single-axis catalog value. Suzhou Zhongbai Robot Technology Co., Ltd. builds single-axis to multi-axis integrated solutions, so the same load case can be checked across the full assembly rather than one module at a time.
Duty cycle, ambient conditions, and contamination all reduce usable load capacity. A high duty cycle raises belt temperature and accelerates tooth wear, so derate the catalog value when the module runs continuously. Dust, chips, and moisture attack the belt and rail; a fully enclosed belt module protects the drive but does not raise the belt limit. For clean-room or food-grade belts, confirm the allowable tension with the belt supplier. If any of these conditions apply, state them when requesting a verified rating instead of applying a blanket derating factor.
Belt wear, tooth skipping, and growing backlash are the first signs that a module is running above its load capacity. Check belt tension at the interval given in the manual , inspect the belt teeth for cracking, and measure backlash against the repeatability specification. A module rated at ±0.05 mm repeatability that shows increasing backlash is usually overloaded or under-tensioned. Record the inspection results so the supplier can compare them with the original load case.
A verified load rating needs five inputs: payload mass, stroke, speed and acceleration profile, orientation (horizontal, vertical, or cantilever), and the number of axes stacked on the module. Add the center-of-gravity offset if the payload is not centered, because offset mass turns into a moment load on the rail. Stroke matters because a longer belt span flexes more under tension. For reference, belt modules in the ZW series offer lead options of 75 / 95 / 190 mm and a single-axis length of about 4 m with spliced customization, so long-stroke layouts are possible but must be checked as a separate load case. Without these inputs, any quoted figure is an estimate, not a rating.
Compare modules on the same load case, not on catalog payload alone. A belt-driven module trades payload and stiffness for speed and long stroke; a screw module trades speed for thrust and rigidity; a rack-and-pinion module suits very long travel. Ask for the allowable moment (pitch, yaw, and roll) and the deflection at the stroke end, since these often limit a setup before the payload figure does. Repeatability is a separate specification: ±0.05 mm is available as an option, but it does not by itself indicate load capacity. Request the calculation sheet for your exact stroke and speed so the comparison uses identical assumptions.
Catalog payload is measured under a defined test condition; application payload is what your motion profile actually allows. The gap comes from acceleration, moment arm, stroke, and duty cycle. A module that carries a given mass at low acceleration may not carry the same mass at high acceleration, because belt tension scales with acceleration force. Treat the catalog value as an upper bound and confirm the application value with the supplier. For a multi-axis build, send the full assembly layout so the load case is checked per axis rather than per module.
Suzhou Zhongbai Robot Technology Co., Ltd. is a robot module integration solution provider serving automation equipment manufacturers and system integrators with robot modules, linear transmission components, and single-axis to multi-axis integrated solutions. The product range covers synchronous belt silent modules, rail-embedded belt modules, screw modules, rack-and-pinion modules, servo electric cylinders, linear guides, and ball screws, with CE certification shown. To have a load case reviewed, send the payload, stroke, speed profile, orientation, and axis count to zhaohaijun@zenbotsmart.com or call 15371836239. Address: 5A, Building 4, Liandong U Valley, No. 25 Datong Road, Suzhou High-tech Zone, Jiangsu Province. Lead time and minimum order quantity are 7-10dayand 1.
A: Calculate three limits: belt force (allowable tension × teeth in mesh ÷ safety factor ≥1.5), rail moment (force × offset distance vs. catalog Mx/My/Mz), and acceleration force (mass × acceleration). The lowest result governs. For horizontal motion, rail and carriage usually limit; for vertical, belt and brake matter more.
A: Yes. Longer stroke increases belt stretch and whip, reducing effective capacity. Derate by [TBD: derate per meter] % per meter beyond [TBD: base stroke] m. For strokes near 4 m, request a verified load-speed curve from the supplier.
A: Use a minimum safety factor of 1.5 for dynamic loads and 2.0 for shock or vertical loads. Always compare peak acceleration force, not just static payload, against the belt's allowable dynamic tension.