Automobile Wheels
Wheels rims are made very truly aligned and are strong enough to carry the weight of vehicle through Tyres.
Wheels are connected to the rear axles. As the rear axle turns, wheels also turn and the vehicle moves on the road.
The wheel assembly generally consist of hub, disc (or) spokes, rim, tyres and tube.
Wheels are as important part of a vehicle as the other parts, all the parts being perfectly in working order, the vehicle can't move on the road without the wheels.
The wheels not only support the weight of the vehicle, but also protect if from the road shocks. Whereas the rear wheels move the vehicle, the front wheels steer it.
All the four must resist the braking stresses and withstand side thrust.
Functions of wheels
1) Strong enough to withstand weight of the vehicle.
2) Flexible to absorb the road shocks.
3) Able to grip the road surface.
4) Perfectly balanced dynamically and statically.
5) Possible to remove (or) mount the wheel easily.
Types of wheels
1) Disc wheel
2) Wire wheel
3) Split wheel
4) Heavy vehicle wheels
1) Disc wheel
This type of wheel consist of two parts a steel rim which is well based to receive the tyre and a pressed steel disc.
The rim and the disc may be integral permanently attached the function of spokes. The hub cap ( or ) cover is usually held in position by spring clips attached to the disc.
The wheel assembly is bolted to the brake drum. Some slots are generally provided in the wheel disc to allow the air to pass to the inner side for better cooling of the brake drum inside.
A hole in the rim serves to accommodate tube valve. This type of wheel is simple, cheap and robust in construction.
It is most commonly used in heavy motor vehicles, cars, buses, trucks, tractors.
2) Wire wheel
This type of wheel consist of a separate hub, which is attached to the rim through a number of wire spokes.
The spokes carry the weight, transmit the driving and braking torques and withstand the sides forces while cornering in tension.
The spokes are mounted in a complicated criss-cross fashion in all the three planes. The headed inner ends of the spokes fit in the holes and the threaded outer ends fit in the rim holes, where mush room headed tubulor nuts are screwed through the rims holes to tighten the spokes.
The spokes do not stick straight out as radii from the hub, but alternate spokes are screwed to slope forward and backward toward the rim.
This arrangement of spokes serves special purpose of the wheel. The forward sloping spokes absorb braking torque and the backward sloping spokes convey driving torque.
A rubber chafing band is fitted in the well of the rim to keep tube touching the spoke nuts.
The initial tension of the spokes can be adjusted by means of screw nipples which also serve to secure the spokes to the rim.
The hub is provided with internal splines to correspond to the splines provided on the axle shaft. A wing nut screws the hub on the axle shaft.
The advantages of this type of wheel is light weight and high strength and above all it provide much better cooling of the brake drum.
It is also very easy to change the wheel when required, because only one nut has to be opened.
They are lighter in weight then other types of wheels and used in lighter motor vehicle racing cars, scooters, motor cycles.
3) Split wheel
The split wheel is made in the form of two dishes which fit back to back and are clamped by a separate outer ring of studs.
The flanges of the discs thus give a seating for the tyre and clamp on the beads. A thick section rubber ring is some times fitted in the gap between the two beads.
The main advantage of split wheel is that the type may be easily taken out of the wheel by unscrewing the nuts and separating the two discs.
4) Heavy vehicle wheels
The heavy vehicle wheels are made in the same way as the disc wheels but much thicker plate is used.
To tighten the wheel and also to increase air flow to the brake drum, large holes are made around the disc.
The wheel nut recesses are usually machined instead of being embossed.
In the case of twin rear wheels, the inner wheel may have a longer valve stem to reach through the outer wheel for case of inflation and pressure check.
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