Question Set 3 – Mechanical Engineering

# Question Set 3

Question No. 1

State the difference between Unilateral and Bilateral Tolerance?

A unilateral tolerance is tolerance in which variation is permitted only in one direction from the specified direction. e.g. 1800 +0.000/-0.060

Bilateral tolerance is tolerance in which variation is permitted in both directions from the specified direction. e.g. 1800 +0.060/-0.060

Question No. 2

What is the abbreviation of welding rod 7018?

7018 is equal to

70 = tensile strength 70000 psi

1= welding position

8 = current flux

Question No. 3

What is difference between Welding and Brazing?

In Welding concentrated heat (high temperature) is applied at the joint of metal and fuse together.

In Brazing involves significantly lower temperatures and does not entail the melting of base metals. Instead, a filler metal is melted and forced to flow into the joint through capillary action.

Question No. 4

How to calculate bearing number from shaft Diameter?

Divide the shaft diameter size by 5, it will give last two digits of the bearing no. and according to type of load we have to choose the type of bearing and that will give prior number of the bearing.

Question No. 5

Explain Bicycle Rear Wheel Sprocket working?

Rear wheel sprocket works under the principle of ratchet and pawl.

Question No.6

The Fatigue life of a part can be improved by?

Improving the surface finish by Polishing & providing residual stress by Shot peening.

Question No. 7

Poisson’s Ratio is higher in Rubber, Steel or Wood?

When a material is compressed in one direction, it usually tends to expand in the other two directions perpendicular to the direction of compression. This phenomenon is called the Poisson effect. Poisson’s ratio is a measure of the Poisson effect.

For rubber = 0.5

For steel = 0.288

For wood < 0.2

Thus Poisson’s ratio is higher in RUBBER.

Question No. 8

What is the other name of Micrometer & Vernier Calliper?

Micrometer’s other name is Screw Gauze & Vernier calliper’s other name is slide calliper.

Question No. 9

What is the need for drafting?

Drafting is the allowances give to casting process. It also used to remove the casting from mould without damage of corners.

Question No. 10