Engineering graphics applied to the assembly process of a single-cylinder highpressure steam engine with CORLISS valve gear

Abstract

This paper presents a detailed description of the assembly process for the different components of a historical invention, specifically a high-pressure single-cylinder steam engine with a Corliss valve gear designed by Arnold Throp, as published in the 'Model Engineer' magazine in 1982 and whose original plans were reproduced by Julius de Waal in 2018. This assembly process serves as a preliminary step towards explaining the operation of the invention. Autodesk Inventor Professional 2024 was employed to create a coherent and functional 3D CAD model that incorporates all components described in the reproduced plans. However, challenges arose due to missing dimensions in the available plans and certain inconsistencies, necessitating the formulation of hypotheses regarding the geometries of some elements and the estimation of their dimensions. Additionally, a series of dimensional, geometric, and kinematic constraints (degrees of freedom) were applied to ensure a proper assembly without component overlaps. Furthermore, a limitation was encountered when using Autodesk Inventor Professional for assembling the invention: the software does not take into account for the deformation of components made of elastomeric materials such as the drive belt. Finally, once the 3D CAD model was obtained, graphical documentation of the invention was produced (including assembly plans and detailed perspectives), and a simulation of the invention's operation was conducted, resulting in a virtual recreation of the steam engine. This has provided new insights that facilitate a more comprehensive understanding of the invention and its dissemination to the wider community.