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## Parallel and transverse Weld

## Design of screw jack

## A helical compeersion imperssion speraing

## Fig 2 show a C.I. bracket to carryof a shaft

## Define following terms of spring:

(i) Spring rate: The spring rate is defined as the load required per unit deflection of the spring. It is also

known as spring stiffness or spring constant. Mathematically,

Spring rate, k = W / δ

Where,

W = Load

δ = Deflection of the spring

(ii) Spring index: The spring index is defined as the ratio of the mean diameter of the coil to the

diameter of the wire. Mathematically,

Spring index, C = D / d

Where,

D = Mean diameter of the coil

d = Diameter of the wire

## Define stress concentration. What are the causes of stress concentration? State any four methods of reducing stress concentration with neat sketches.

Stress concentration: Whenever a machine component changes the shape of its cross section, the simple stress distribution no longer holds good and the neighbourhood of the discontinuity is different. This irregularity in the stress distribution caused by abrupt changes of form is called ‘stress concentration’.

## In a rigid flaninged complended to transmit 20K.W at 700.r.p.m

## Fig.1Show of hacksaw The belt is assembled with tensoion

## (ii) How will select bearing from manufacturer catalogue?

The following steps must be adopted in selecting the bearing from the manufacturer’s catalogue: 1. Calculate the radial and axial load reaction (Fa and Fr) acting on the bearing. 2. Decide the diameter of the shaft on which the bearing is to be mounted. 3. Select the proper size of bearing suitable for given application, specified with speed and available space. 4. Find the basic static rating Co of the selected bearing from the catalogue. 5. Calculate the ratio (Fa / VFr) and (Fa / Co). 6. Find the value of x and y i. e. radial and thrust factor from the catalogue.