Description / Abstract:
This test procedure is intended to apply to hydraulic pump
suction filters and strainers used in automotive automatic
transmissions that include hydraulic power pumps. The various
paragraphs of Section 5. "These Procedures," include a variety of
tests and alternative tests that are not applicable to all filters
and applications, so the engineer must specify which tests are to
be performed for a particular application. These test procedures
are intended to evaluate filter functional performance
characteristics only, durability is not evaluated under this
standard.
Filter design requirements must be specified by the engineer on
the filter assembly drawing, an applicable engineering
specification, or summarized on an application data sheet similar
to that found in this recommended practice.
Pressure circuit filters, both barrier and system contamination
control types, are not covered under this standard. They are
similar in design and construction to filters used in many
hydraulic and lubricating applications.
Purpose
The purpose of this standard is to establish test methods to
evaluate critical performance characteristics of automatic
transmission intake (suction) filters. These filters need ratings
for flow capacity, temperature range, contaminant capacity, filter
efficiency and other critical functional characteristics. These
characteristics should be representative of a production feasible
design and are to be applied to the filter assembly. Pressure side
filters are covered by other existing test standards and
practices.
Prior use of "nominal" and "absolute" filter ratings as applied
to a filter's ability to capture practice of a given size have been
deprecated. This standard predicates the use of "Filtration Ratios"
(efficiency) or "Beta Ratios" to describe the capture effectiveness
under reproducible test conditions using a known test
contaminant.