Traditional models of high pressure grinding rolls (HPGR) crushers rely heavily on survey data to make accurate predictions. In this paper, a consolidation of previous approaches of modeling comminution machines is combined with insights from crusher modeling to develop a time dynamic process model of the HPGR. The crusher is modeled from a mechanistic point of view. Dynamic responses of the effect of hydraulic systems with dampening, varying feed size, ore hardness and crusher behavior for roller speed changes are included. The outcome is a full-time dynamic model that has been compared to process data. The model runs in Simulink and is supplied with a hydraulic cylinder pressure signal. The modeling technique is based on the mechanical motion equations of the rollers, combined with the breakage characteristics and pressure response of the ore material. The motion of the roller is partially described by the differential equation of a spring damper system. The block-based physical modeling is based on work by Evertsson (2000) and Johansson (2017), now applied to the HPGR crusher. A crusher performance model is presented, including capacity, particle size, and power estimation. The model output has been compared to data for an HPGR crusher with one ore, with an average correspondence within 10%, which leaves room for further improvements. The final model is assembled in a modular way, allowing for both process simulations of circuits and more high fidelity investigations of stand-alone units.