The number of shift that planetary gear transmission can carry out
which has three-degree of freedom and three-planet-row
is analyzed with the lever analogy.The layout of the basic joint element of this kind of transmission
the mode of its planetary-gear-row and all drive diagrams is studied
and then a feasible project is carried out.In addition
all kinds of drive scheme are analyzed comprehensively with corresponding computer auxiliary analysis program.Finally
a fuzzy mathematical model is created.With this model the drive scheme of this kind of transmission can be assessed quantitively and the result of assessment can be obtained.