This paper describes the simulation model of a backhoe excavator. The model uses a prescribed motion cycle and the objective of the program is to determine the power requirements for each of the cylinders as well as the total engine power requirement.Most computer simulations are developed by expressing the differential equations of motion for the system being studied. The known force inputs to the system are applied and the time response of the system is then obtained by numerically integrating the governing differential equations.This paper on the other hand develops the reverse of this. Utilizing a prescribed geometry and trajectory cycle for a linkage system as the input, the program solves for the types of force inputs that are required to achieve that trajectory. With the time dependence of the trajectory known, the total power required and the power required of each cylinder is also evaluated.A typical excavator linkage is shown in Fig. 1. It consists of four link members; the bucket, the stick, the boom, and the house. In order to simplify the computer model, a rotating coordinate system is used. This coordinate system is attached to the swing bearing of the house, and the links are considered to move in the X-Y coordinate frame and the entire assembly rotates in the θ-direction.