  In the rotational sandpile model, either the clockwise or the anti-clockwise
toppling rule is assigned to all the lattice sites. It has all the features of
a stochastic sandpile model but belongs to a different universality class than
the Manna class. A crossover from rotational to Manna universality class is
studied by constructing a random rotational sandpile model and assigning
randomly clockwise and anti-clockwise rotational toppling rules to the lattice
sites. The steady state and the respective critical behaviour of the present
model are found to have a strong and continuous dependence on the fraction of
the lattice sites having the anti-clockwise (or clockwise) rotational toppling
rule. As the anti-clockwise and clockwise toppling rules exist in equal
proportions, it is found that the model reproduces critical behaviour of the
Manna model. It is then further evidence of the existence of the Manna class,
in contradiction with some recent observations of the non-existence of the
Manna class.
