5at Train

The 5AT Group - Steaming Ahead with Advanced Technology

Enhancing Performance -- Improving Reliability -- Reducing Costs -- Controlling Emissions

Reducing Maintenance Costs

Note: On page 144 of his book, Wardale makes the point that in the broader meanings of the words, reducing maintenance costs could fall into the category of improving Performance and Efficiency.   Notwithstanding, this page relates to the narrower meanings of the phrase "reducing maintenance costs".

Just as boosting performance and reducing fuel consumption are largely interrelated aims, so too are reducing maintenance and increasing reliability.

This page looks only at modernisation options that will reduce maintenance costs.  The items that are listed are taken from the table on the introductary "Modernisation Options" page.  They include:

  • Improved valve and piston lubrication through the application of lubricants directly onto the rubbing surfaces rather than atomising and mixing it with superheated steam as has been commonly practiced;
  • Use of multiple narrow valve and piston rings to improve and maintain steam-tightness, and reduce wear rates;
  • Use of multiple element floating packing on piston and valve rods to eliminate steam leakage between overhauls;
  • Modify valve heads to promote cooling and thus improve lubrication - e.g. by fitting diffusers to direct (cool) exhaust steam over the (hot) admission ends of the valve heads - see diagram on Valve Design page;
  • Where very high superheat temperatures are used, provide saturated steam cooling of valve liners to reduce surface temperatures and thus slow down the decomposition of lubricant oils - see diagram on Valve Design page;
  • Welding bronze bearing surfaces on valve heads (that rub directly on their liners) and on piston heads where tail rods are not provided to keep the heads clear of their liners;
  • Fit roller bearings to all axles, crankpins and motion to minimize wear;
  • Fit Franklin wedges to axleboxes to maintain zero clearance between axleboxes and horn guides, preventing the shock loads or "knocks" from reversal of piston thrust and the general wear that results therefrom.
  • Fit Franklin buffing mechanism
  • Fit air sanding equipment to improve adhesion and prevent slipping (and the damage associated with it).  Include steam rail washers behind driving wheels to remove sand and thereby reduce wear on trailing and tender wheels.
  • Adopt Porta water treatment to minimize boiler deterioration and maintenance.
  • Remove or disconnect snifting valves and adopt mid-gear drifting.
  • Reprofile driving wheels regularly to maintain circularity and to keep the driven wheels some 3 to 6mm greater in diameter than the coupled wheels.