Cad Design

							The design data hand book has been compiled in both metric and
international system (S.I) of units the following few illustration regarding the
usage of the hand book in both the units have been given for better utilization
of the hand book.

Symbols: For each symbol (which is same in both the cases), the relevant units
used are indicated against each symbols.

      Fr = radial force acting on the tooth N (kgf).

The units in metric system for Fr is kgf and in SI system N. The unit in metric
system for each symbol has been indicated within the brackets whereas in SI
system is written prior to the metric unit.

      A = cross-sectional area, mm²

The unit for the cross-sectional area. A in both the system is same, mm²

Formulae:

In flat belts the relation between the stress σ = C₁² e²

                                      Elongation e

Where       σ =stress in belt, MN/m² (kgf/mm²)

            e = elongation, mm/mm

            C₁ = a constant

               = 70(22.35) for leather belts.

The value of the constant C₁ in SI system is 70 and in metric system it is 22.35
which have been within the brackets.

Material                        allowable static stress            BHN

                                  MN/m² (kgf/mm²)

Cast iron grade 20                    47.1(4.80)                   200

Cast iron grade 25                    56.4(5.75)                   220