Machine element analysis has a goal of describing function and other a
spects of machine elements in a theoretical form. This paper shows how
ideas from object-oriented modelling can be applied to machine elemen
t analysis. The models thus obtained are both easier to understand, be
tter structured, and allow a higher degree of re-use than conventional
models. An object-oriented model description is natural and suitable
for machine element analysis. As a realistic example an equational mod
el of rolling bearings is presented. The structure of the model is gen
eral, and applies to many types of rolling bearings. The model and one
solution require approximately 200 + 200 equations. The model is exte
nsible, e.g. simple submodels of detailed properties can be made more
complex without altering the overall structure. The example model has
been implemented in a language of our own design, ObjectMath (Object-o
riented Mathematical language for scientific computing). Using ObjectM
ath, it is possible to model classes of equation objects, to support m
ultiple and single inheritance of equations, to support composition of
equations, and to solve systems of equations. Algebraic transformatio
ns can conveniently be done since ObjectMath models are translated int
o the Mathematica computer algebra language. When necessary, equations
can be transformed to C+ + code for efficient numerical solution. The
re-use of equations through inheritance reduced the size of the model
by a factor of two, compared to a direct representation of the model
in the Mathematica computer algebra language.