Steam Loco Definitions

Technical Terms and Definitions relating to Steam Locomotives

The following pages are provided to guide people who are not familiar with steam locomotive terminology.  The list is by no means complete and may be added to in the future.  Contributions from readers will be welcome.

• Thermal Efficiency
• Power and Indicator Diagrams
• Power-to-Weight Ratio
• Equivalent Evaporation
• Specific Steam Consumption
• The Grate Limit and Boiler Efficiency
• Front End Limit
• Tractive Effort
• Adhesion
• Resistance
• Simple/Compound
• Motion
• Valves, Valve Gear etc
  • Reuleaux Diagram
• Snifting, Drifting, Bypass and Herdner Valves
• Balancing & Hammer Blow
• Combustion Air (still to be written)
• Superheating
• Steam Chest
• Clearance Volume
• Condensation/Wall Effects
• Triangular Losses
• Incomplete Expansion
• Exhausts
• Brakes