  Some models of clustering processes are formulated and analytically solved
employing generating functions methods. Those models include events which
result from combined action of the coagulation and fragmentation processes.
Fragmentation processes of two kinds, so-called similar and arbitrary, ones,
are brought forward, and the explicit forms of their solutions are produced.
This implies some possibility of existence of different aggregation mechanisms
for clusters creation differing in their inner structure. All the models are
based on "the three-level bunch" scheme of interaction between the system
states. Those states are described in terms of the probability to find the
system in the state with an exactly given number of clusters. The models are
linear in the probability functions due to the assumption that the rates of
elementary acts are permanent. Some peculiarities of application of the
generating function method to solution of the linear differential-difference
equations are revealed. The illustration of the problem in terms of a traffic
jam picture is not a specific one.
