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, "Test 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 they may be summarized on an application data sheet similar to that found in this recommended practice. See Figure 6, "Filter Assembly Application and Data Sheet."

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 units 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 particles 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.

Rationale

Not applicable.