This document covers evaluation techniques for determining the power consumption characteristics of hydraulic pumps used on heavy-duty trucks and buses. The testing technique outlined in this SAE Recommended Practice was developed as part of an overall program for testing and evaluating fuel consumption of heavy-duty trucks and buses. The technique outlined in this document provides a description of the test to be run to determine power consumption of these engine driven components, the type of equipment and facilities which are generally required to perform these tests are discussed in SAE J 745. It is recommended that the specific operating conditions suggested throughout the test be carefully reviewed on the basis of actual data obtained on the specific vehicle operation.