It is proved that, under fairly general conditions, the canonical Poin
care-Chetayev equations are Hamiltonian equations in non-canonical var
iables. It is shown that systems of generalized Lagrange and Hamilton
equations in redundant variables, of lower order than equations that c
ontain undetermined multipliers, as well as the Euler-Lagrange equatio
ns in quasi-coordinates, are all special cases of the Poincare-Chetaye
v equations. Thus the theory of the latter extends at once to the type
s of systems just listed. The problem of using the Poincare-Chetayev e
quations in non-holonomic dynamics is discussed.