5AT Maintenance Costs
Just as the 5AT’s reliability is expected to be exceptional even by modern traction standards, its maintenance costs are also expected to be very low.
In the past, the highest maintenance costs item on a steam locomotives was its boiler which, besides monthly washouts, required major overhaul at every 200,000 or 300,000 km or even less depending on usage. Porta’s water treatment system will ensure that the 5AT’s boiler should suffer near-zero corrosion and no accumulation of sludge or scale, all of which were the major contributors to maintenance costs on First Generation Steam locomotive boilers. As such boiler washouts intervals are expected to exceed 6 months, and the boiler itself will be welded to its saddle because it is not expected to need lifting during the 30 year/1.5 million km planned life of the locomotive.
Cylinder wear is expected to be so low that the 5AT’s cylinder liners are also expected to last the life of the locomotive, and the valve liners are expected to need replacement only once in that time. The roller bearings fitted to axles and motion are also expected to require minimal maintenance.
A list of technical features of the 5AT that will reduce maintenance costs and improve reliability is provided in the FAQ section. To these, can be added the extraordinarily low maintenance requirements that Porta achieved with his modified fleet of diminutive 2-10-2 Santa Fe locomotives that operated on the Rio Turbio Railway in Argentina in the 1960s. These improvements are listed in Wardale’s book as follows:
480,000 km before main (white metal) bearings needed replacing. This distance represented 180 million revolutions of their 850mm diameter driving wheels. Much greater distances could have been run with roller bearing axle-boxes.
70,000 km between tyre profiling = 26 million revolutions;
No superheater replacements in 500,000 km despite high steam temperatures (>400oC);
No boiler tube replacement in 400,000 km (apart from tubes damaged during installation);
No boiler repairs in 400,000 km of service;
Piston rod packings lasted 400,000 km (150 million revolutions);
Maximum steam leakage rate: 1.7% of maximum boiler evaporation after 70,000 km.