  Quasi-biennial oscillation (QBO) is a well-known quasi-periodical variation
with characteristic time 0.5-4 years in different solar, heliospheric and
cosmic ray characteristics. In this paper a hypothesis is checked on the causes
of the apparent lack of correlation between solar and heliospheric QBOs, then
the possible mechanisms of QBO in the GCR intensity are discussed as well as
the idea of the same nature of the step-like changes and Gnevyshev Gap effects
in the GCR intensity.
  Our main conclusions are as follows: 1) In the first approximation the
hypothesis is justified that the change in the sunspot and QBO cycles in the
transition from the Sun to the heliosphere is due to 1) the different magnitude
and time behavior of the large-scale and small-scale photospheric solar
magnetic fields and 2) the stronger attenuation of the small-scale fields in
this transition. 2) As the QBO in the HMF strength influences both the
diffusion coefficients and drift velocity, it can give rise to the complex QBO
in the GCR intensity with respect to the dominating HMF polarity. The
description of drift velocity field for the periods of the HMF inversion is
suggested, although it has drawbacks. 3) As the conditions in the heliosphere
are quite different around the sunspot maximum and during the periods of low
solar activity (both with respect to the HMF polarity distribution and with the
presence or absence of the large-scale barriers), the suggestion that both the
step-like changes of the GCR intensity and Gnevyshev Gap effect could have the
same nature, looks questionable.
