Río Turbio Modified Santa Fe Locomotives
Indicator Diagrams

These indicator diagrams for the 2-10-2s are taken from Porta's 1990 lecture given to the XVIII Collogue, ICOHTEC, Paris.

Porta made the following observations on the pages containing these diagrams:

Corrected according to the Börth method. Piston and valve rings ~70000km. It is seen even with Walschaerts gear the diagram can be as good as for those of Poppet valves.

The very low back pressures are apparent. Also triangular losses resulting from a sharp definition of valve events are minimum. This is the result of a very good streamlining obtaining when the ports are closed.

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