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The development of a mathematical model of StillerSmith Mechanism for the application of a 4-cylinder plunger pump system is presented. The magnitude and direction of the internal dynamic load are obtained by solving a set of equations using the overall geometric parameters, prescribed motions, inertia distribution, and applied torques on the system. The simulation presented here yields the history of the internal loads, which are then normalized with respect to the required peak output load on the plungers, through an entire rotary cycle. The approach allows for the development of further design criteria through parametric sensitivity studies.

The Scotch yoke in its various forms and inversions has received considerable attention as possible alternatives to the slider-crank for internal combustion engine use. As a recent entry, the Stiller-Smith Mechanism has shown promise as being a viable and strong option. In this study emphasis was placed on comparing the number and similarity of mechanism components and the balancing aspects of these components, implications of component and linkage motions, the severity of loading experienced by similar bearing surfaces within the engines, and some of the friction losses associated with these new motions. It was found that the Stiller-Smith Engine has significantly fewer moving parts. It was also found that journal bearings in the slider-crank engine were more severely loaded than those in the Stiller-Smith Engine. The linear reciprocating bearings in the Stiller-Smith Engine were more heavily loaded than the slider-crank piston skirts.