Wheel along with tire is the only point of contact between the road and vehicle. They help to provide a cushioning effect, take the vertical load and cope with the steering control also at the same time.
The requirements of wheels are-
- It should be balanced both statically and dynamically.
- It should be lightweight to keep the unsprung weight down.
- It should be easy to mount and remove.
- It should not deteriorate with age.
Types of wheels-
- Disc Wheels– They consist of two parts, a steel rim, and a pressed disc. The rim profile is indicated with letters J, K, JJ, JK which comply with different tire bead profile. Well helps to mount and remove the tire from the wheel as the bead rests in the well. The wheels are attached to the axle by tightening the nuts onto the studs fixed on the flanges on the axle. These studs act as a guide for mounting holes on wheels. Some slots are further provided to allow air to the inner side for better cooling. Since holes tend to weaken the disc the holes in modern wheels are swaged, some portion of the disc around each hole is turned inwards. It compensates for the lost strength. They require negligible maintenance and are easy to produce.
- Applications– Heavy vehicles.
- Wire Wheels– They have a separate hub attached to the rim by a number of wire spokes. If the spoke is too loose or too tight, the rim would distort. The spokes carry the weight of the vehicle, transmit the driving and braking torques and withstand the side forces while cornering. The spokes cannot take compressive or bending stresses. The spokes are mounted in a complicated fashion to make them able to take the forces with better strength. The tension of the spokes can be adjusted using the screw nipples, which also secure the spokes to the rim. The hub has internal splines which correspond to the splines on the axle shaft and a wing nut screws the hub on the axle shaft. These wheels provide excellent cooling of the brake drum and are easy to mount and remove. But they are expensive due to their construction and tubeless tire cannot be used on these wheels.
- Applications– Racing Cars, Vintage cars.
- Light Alloy cast or forged wheel– They are cast from aluminum and magnesium alloys. They are about 50% lighter than the steel and have similar strength. They are also good conductors of heat and help to dissipate the heat generated by brakes and tires. They help to make wider wheels which give better stability on corners. Being prone to corrosion these wheels need some protective coating.
- Applications– cars, light commercial vehicles, sports cars.
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