How to Calculate the Width of Gear Hub?
2 Answers
The width of the gear hub shaft is mainly determined based on the axial dimensions of the parts that fit with the shaft and the necessary gaps between adjacent parts. Below is extended information about the hub: 1. Hub bearings: In the past, car hub bearings were most commonly used in pairs with single-row tapered roller or ball bearings. With technological advancements, cars now widely use hub units. The application scope and usage of hub bearing units have been increasing, evolving to the third generation: the first generation consists of double-row angular contact bearings. 2. Fixing methods: The second generation features a flange on the outer raceway for securing the bearing, allowing the bearing to be simply slipped onto the axle and fixed with a nut, making car maintenance easier. The third-generation hub bearing unit integrates the bearing unit with the anti-lock braking system. The hub unit is designed with inner and outer flanges; the inner flange is bolted to the drive shaft, while the outer flange assembles the entire bearing together.
When I used to repair cars, I often dealt with gear hub width calculations, relying on a simple formula: the hub width W is generally 1.2 to 1.5 times the shaft diameter D. For example, if the shaft diameter is 20mm, the width should be designed between 24mm and 30mm. The specific value depends on the gear load—heavy-duty vehicles take the upper limit, while daily family cars take the median value. Once, while modifying a racing gearbox, I found the hub was too narrow and cracked—a lesson that material strength must be considered; steel gears can be narrower, while aluminum ones must be wider. Additionally, the gear type has an impact: helical gears, to resist torque, are typically about 0.2 times wider than spur gears. Always leave a safety margin in calculations to prevent detachment at high speeds, and during routine maintenance, it’s advisable to measure dimensions accurately—don’t rely on guesswork.
