Engine designs were under constant development and patents awarded multiplied with improvements to drive train assemblies, firebox and fuel efficiencies, and fabricating techniques. The construction of tight boiler joints and seals was particularly important. Baldwin's introduction of ground joints for steam pipes permitted increase of boiler pressure from 60 psi to 120 psi with corresponding improvement in thermodynamic efficiency. Other patented advances included an equalizer to distribute shocks from rough rails and keep the train on the tracks, an arrester to prevent dangerous sparks from leaving the smokestack, and a draft maker to improve fuel burning quality.
In 1892, rules were set by Purdue University for scientific testing of locomotive performance. The areas covered were traction power measurement, furnace conditions, and fuel and water analysis. New, formal design standards simplified and replaced the previous "try it and see" approach used previously.
While it took skill and ingenuity to build locomotives, equal qualities were required of those who operated them. With few automated controls available, the operating team had to ensure that the raw material, water and coal, supply was exactly right and that the driving steam energy was properly applied and controlled so that the team of man and machine could function well.