Answer to Question #189747 in Mechanical Engineering for Yashwanth Kumar

Question

3. Explain briefly tyre failure and their causes. Explain the different methods used for wheel balance. Discuss the procedure for tyre rotation for four and six wheeled vehicles. Describe the two methods used to repair a tubeless tyre 

Answer 1

Tyre failure occurs when there is a defect or weakness in the material or design of a tire.

Tyre failure can be caused by Tread separation;

• Tread and steel belt separation.
• Tyre made without all specified components.
• Belt and ply losses.
• Improper puncture repair.
• Tyre not suitable for vehicle.
• Sidewall failure.
• Retread failure.

The two main methods used for wheel balancing are

$1.$ Static balancing

If there is only a slight imbalance to the tire, static balancing is the appropriate technique and is relatively easy to do; the wheel and tire assembly is placed onto a vertical supporting device with a spindle or equivalent to measure balancing on one axis. The heavier side will lean lower to the ground than the lighter side; once identified, the mechanic will place a small weight measuring fractions of an ounce 180 degrees across the plane of the tire, onto the flange of the wheel rim, until the balance is restored.

2. Dynamic balancing

For more complex cases of tire imbalance, dynamic balancing is a technique using spinning computer balancers to measure the tire on all three axes. The mechanic places a fully assembled wheel and tire on a machine and rotates it at speed ranging from 16-25 km/h (10-15 mph) to 88-96 km/h (55-60 mph). As it spins, the sensors of the machine capture every single weight imperfection.

With the analysis complete, the computer then specifies how much weight and where the mechanic should apply to balance the tire. The small weights – either clip-on or adhesive weights – are added to both the inner and outer sides of the wheel rim, to provide the highest precision and balance.

- procedure for rotation of four wheeled vehicles:

the front tyres are installed in the corresponding rear hubs and the rear tyres are installed on the front hubs right opposite to their position.

- procedure for rotation of six wheeled vehicles:

If the ehicle has dual rear wheels the rotation pattern looks like two triangles, one on the driver’s side and one on the passenger’s side. For each side, move the outer dual tire to the inner position, the inner dual tire to the steer position and the steer tire to the outer dual position.

Methods used to repair a tubeless tyre

Procedure:

1. Park your car and try to find out the piece of nail or metal that has pierced through the tyre and causing the air to leak.

2. It’s not always needed, but in case you are having trouble finding out the piece that has punctured the tyre, it might be better to remove the wheel. It’s absolutely necessary that you take precautions while removing the flat tyre. Instructions – How to remove a flat tyre?

3. Remove the piece of nail or metal carefully with a plier. This would cause the air to leak more quickly, but you don’t need to worry about this since you can pump in air afterwards with the pump.

4. Prepare the split eye insertion needle tool by inserting the rubber wick in it. Let the wick stick out equally with the insertion needle in the middle.

5. Insert the rasp tool into the hole with screwing action until it is fully in. This would enlarge it slightly and would help prepare the surface for sticking the rubber piece.

6. Use the vulcanizing solution and apply it all around on the prepared rubber wick before inserting it into the enlarged hole.

7. Insert the split-eye insertion needle into the hole such that only about 1/3rd of the rubber wick sticks out and the rest goes in.

8. Remove the split-eye needle, it will cause the rubber wick to stay in the hole inside the tyre and seal it. The remaining portion will stay out as you remove the needle.

9. Cut the extra portion of the rubber wick that’s sticking out of the hole as closely as you can.

10. Inflate the tyre to the correct pressure using electric air pump.