2. Some definitions of push and pull systems
It has already been observed that most manufacturing
control systems are hybrid, i.e. a mixture of
both push and pull. However, this observation is
not very meaningful if the terms push and pull have
been left deliberately vague. In order to clarify the
terms, we examined papers which discussed the
performance of push and pull systems. The papers
are broadly of two kinds: firstly those by authors
who have tried to investigate push and pull systems
by simulation and, secondly those by authors who
have looked more descriptively at manufacturing
systems. Broadly, the former investigate well-de-
fined manufacturing sub-systems whilst the latter
have a wider perspective, perhaps referring to the
whole enterprise. The simulation modelling examples
refer to push and pull to identify the type of
system, but necessarily then go on to deÞne in detail
the rules of operation and other parameters which
describe the system modelled. This makes it very
difficult to compare directly the results of these
studies. Views of some of the authors are now
described:
Lee [1] described procedures for push and pull
as follows:
Push