This SAE Aerospace Recommended Practice (ARP) is an application guide for fixed and variable displacement hydraulic motors. It provides details of the characteristics of fixed and variable displacement hydraulic motors@ architectures@ circuit designs@ controls@ and typical applications. The applications include airborne and defense vehicles with emphasis on high performance applications. Purpose The purpose of this document is to apprise the system designer of the available options in the control and application of hydraulic motors and it provides guidance in how to integrate them in a control system.