Lack of steam tightness is usually imagined to be associated with steam leaking from pipe joints and piston rod glands resulting in the familiar leaks that can be seen as a white plume of steam eminating from wherever the leak is occurring. Steam leakage of this sort is indeed wasteful and deletarious to a locomotive’s […]
Incomplete Expansion of Steam in the Cylinder Page Under Development This page is still “under development”. Please contact Chris Newman at webmaster@advanced-steam.org if you would like to help by contributing text to this or any other page. The term “incomplete expansion” is used to describe the curtailment of the expansion of steam inside a locomotive’s […]
Triangular Losses in Cylinders Page Under Development This page is still “under development”. Please contact Chris Newman at webmaster@advanced-steam.org if you would like to help by contributing text to this or any other page. The term “triangular losses” is used to describe the rounding of the corners of a locomotive’s indicator diagram caused by the […]
Wall Effects and Condensation Wall Effects: The term “wall effects” refers to the changes in steam temperature caused by temperature differentials between the steam and the walls of the cylinder, its end covers and the steam passages connecting to it. When high temperature, high pressure steam enters the cylinder, it comes into contact with the […]
Boiler efficiency can be defined as the amount of energy delivered from the boiler in the form of steam divided by the amount of energy delivered to the firebox in the form of fuel/chemical energy. Boiler efficiency depends on the design of the boiler and firebox, the type of fuel, and the draughting system. In […]
Drawbar efficiency can be seen as the sum of the efficiencies of a locomotive’s various components. Wardale provides examples of these in his book “The Red Devil and Other Tales from the Age of Steam” where (in Table 78, page 457) he quotes figures for standard and (proposed) modified Chinese Class QJ locomotives, and where […]
Cylinder efficiency is calculated by dividing the work done by the steam in the cylinder by the heat drop in the cylinder. In Line 84 of FDC 1.3, Wardale calculates the isentropic cylinder efficiency of the 5AT at maximum drawbar power output to be 81%. He gets this figure by dividing the actual specific work […]
Thermal Efficiency The “thermal efficiency” of any engine is defined as the amount of useful energy output divided by the amount of energy input . It is not a fixed quantum but varies according to the engine’s load and conditions of operation. In the case of steam locomotives, the term thermal efficiency may refer to […]