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The choice between a planetary gearbox<\/strong> and a worm gearbox comes down to three numbers: efficiency, torque density, and duty cycle hours per year. Get this choice wrong and you pay for it every month in electricity bills, every year in replacement cycles, and every five years when you redesign the machine. This guide gives you the data to make the right call the first time \u2014 with no marketing language involved.<\/p>\n<\/div>\n A planetary gearbox<\/strong> uses a central sun gear, a set of planet gears orbiting around it, and a fixed outer ring gear. Load is distributed simultaneously across all planet gears \u2014 typically three or four. This is why planetary designs achieve high torque in a small housing: multiple gear meshes share the load rather than a single contact point carrying it all.<\/p>\n A worm gearbox uses a helical worm screw driving a worm wheel at 90\u00b0. The contact is a sliding action \u2014 the worm tooth slides across the wheel face rather than rolling. This sliding generates heat, which is why worm gearboxes run hot and why their efficiency drops sharply as the ratio increases. At a 40:1 ratio, a worm gearbox commonly delivers 60\u201375% efficiency. A planetary gearbox at the same ratio typically delivers 96\u201398%.<\/p>\n The self-locking behaviour of worm gearboxes \u2014 where back-driving is resisted by the gear geometry \u2014 is often cited as an advantage. This is true for applications requiring a mechanical hold without a separate brake. But this same geometry is responsible for the efficiency loss, because any friction that prevents back-driving also dissipates forward-driving energy as heat.<\/p>\nHow Each Gearbox Type Works<\/h2>\n
Head-to-Head Comparison: The Numbers That Matter<\/h2>\n