The thermal rating of enclosed gear drives is
based on the balance between the power lost in
the gear unit and the power exchanged by the
surfaces of the housing for a given service
temperature inside the unit.
The exchange of power is performed by the
following ways: The conduction, the radiation
and the convection.
Obviously, the radiation is a function of the
material of the housing, the coating and the dust
which may cover it.
Concerning the convection, it must be @ distinguished between the natural and the forced
convection.
The value of the coefficient of exchange by way
of convection strongly influence the value of the
total heat exchange coefficient.
In the technical reports IS0 14179 parts 1 and 2,
it is provided values for the coefficient of
exchange in the case of natural convection and in
those of forced convection.
On the basis of the equations of dynamic of fluids
and the equation of heat, our task is to compare
the values of the total heat exchange coefficient
obtained with respect to these given in the
technical reports.