How to Calculate Gear Tooth Width?
2 Answers
Gear tooth width is usually expressed by the tooth width coefficient. The coefficient for helical gears is 0.4, for herringbone gears it ranges from 0.5 to 1.0, for straight bevel gears the tooth width = gear coefficient * outer cone distance; for worm gears, the tooth width = 0.65 * worm pitch diameter. Generally, the larger the tooth width coefficient, the wider the gear, and the greater the load-bearing capacity of the gear, but the uneven distribution of load along the tooth direction also increases. Below is relevant information about gears: 1. Classification: Gears can be classified by tooth profile, gear shape, tooth line shape, the surface where the teeth are located, and manufacturing method. The tooth profile of a gear includes the tooth curve, pressure angle, tooth height, and modification angle. 2. Tooth Width: Tooth width refers to the axial length of the gear tooth's entity, i.e., the 'thickness' of the gear.
When calculating gear tooth width, I usually multiply the tooth width coefficient by the module in practice. During projects, such parameters must be determined based on specific application scenarios, like the vastly different load characteristics between automotive transmissions and construction machinery gearboxes. For heavy-duty applications, a larger coefficient is chosen, while lighter equipment can use a smaller one, typically ranging between 10 and 40. During design, theoretical values alone are insufficient—assembly tolerances and spatial constraints must be considered. Otherwise, excessive tooth width can lead to noise or even tooth breakage. Once, during a test by our team, increasing the tooth width by 10% reduced vibration noise by two decibels and significantly extended lifespan. I recommend beginners simulate stress distribution with software before finalizing designs to avoid rework later.
