How Design Wheel Hub

Mechanics Mens et Manus Series- Wheel hub design

Wheel hub design is a basic knowledge for every mechanical designer. How to make a super low rolling resistance wheel? What kind of bearing should I choose? What feature is a must in my hub design? These doubts will be answered after you read this post.

I come from a mechanical engineering education background. Been working hands-on on various project in university, from design to fabrication. I have been working on cars, karts, engines and recently electric motors. This is my first engineering/design post to share my experience and knowledge.

Choosing the size of your wheel

The first thing that has to come in mind is “What size I want for my wheel?” Normally bicycle comes in 16”, 20”,21”,24”26” diameter wheel size. Do check with local repair shop for these sizes, and the spokes length available. You would want a hub designed and you can't put into a rim because you’ve got no suitable spokes for it. Do design a hub with minimal post machining work.

Big Wheel or Small Wheel?

Big wheel needs a bigger torque to initial the rolling but possesses larger rolling momentum once it rolls on a specific speed.

Therefore, designer needs to play around with the torque formula-Torque=Force x Radius and find the compromising values from these parameter.

Normally, when deciding the wheel size for the vehicle, driving wheel should be as close to sprocket size for minimal force required to drive the veh

icle and driven wheel should be as big as possible to be driven at ease.

Choosing the right type of bearings

What makes the wheel roll? Bearings of course. Normal bicycles use ball bearings; some wheel chairs use sealed bearings. When designing a wheel hub, it is necessary to think what type of forces will be exerted on the wheel. A steered wheel will experience radial force from reaction force from ground, lateral force when the car steers. Hence we need to choose bearing which design for these two predominant forces. Normal seal bearing will only withstand radial force and could not handle lateral axial force. In this case, angular contact bearing is recommended.

There are 2 steps from the ends which are meant for bearing resting. Some design does include a sleeve which synchronize the rotating of the opposite 2 inner race of the bearings. A sleeve looks like a hollow cylinder. It is axially through for the shaft or axle.

During machining, care must be taken when determining bearing tolerance. Remember to make taper for ease of bearing fittings. Press the outer race of the bearing when fitting it into the hub.

Below is my machined wheel hub for my ceramic bearing fits hub.

author: david chew

email: cvk33@msn.com

A Legacy to be Hold

USM Shell Eco Marathon Team embarked a tough journey to Sepang International Circuit on the last July. They finished fabricating their cars just before the race day and only done some testings on the cars.

The journey started early in the morning, we traveled to Sepang Circuit with our restless mind and body due to recent round the clock work. During the race day, we were still working on some minor furnishes and double all the linkages and wirings.

At last, the cars still managed to go on track after both cars passed the inspections.

Actually, things were getting smooth during the inspection. USM GEN2 passed the inspection quite early among the Malaysian teams. We also been selected for the parade during opening ceremony. This car possessed an unique feature of having natural jute composite as material for the shell of the vehicle. It also has a special design of rear wheel steering which catches the attention of all visitor to our pit.

During the track run, we suffered a major blow which prevents us from finishing the laps. Sepang Circuit has a challenge which Europeans competition doesn't have. There is a steep slope for after the second turn. We are lacking gear ratio hence we cant climb the slope. It was disappointing and the team manager- David did not feel good all day long so did Horizon our prof.

It was a great competition after all, the team has a better plan for the next years, in the aspect of technical designs and team management. After all, it was a great education platform. The manager is determined to have a better entry next year with a more solid team and the year coming after, we will show off our true colors in 2012. This is a legacy to bear, a mission started as David, accomplished as a Goliath.