A control system for a Hydraulic Hybrid Propulsion System (HHPS) is proposed and specified. Performance of the control system is evaluated by means of digital computer simulation of the total propulsion system. In order to accomplish this, analytical models of HHPS components are developed. The simulation consists of a city bus negotiating a typical driving cycle developed for this purpose on the basis of actual city bus cycle data. Performance of the control system is found to be satisfactory in all phases of driving cycle with the exception of transition from acceleration to cruise
