5AT Website The 5AT Project website was first set up on 27th Jun 2002 and quite rapidly gained a wide readership from all over the world. A screen image of the original website is shown below. A “hit counter” (as used over the first months) recorded an average of around 30 visitors to the site each day during its first 12 months of operation. However, […]
Advanced Adhesion and Tyre Wear A locomotive must be designed so that its tractive effort is not so high that it “loses its feet” on starting. Equally importantly, its tractive effort should be limited so that it does not slip at speed. This latter becomes a much more important consideration for Second Generation Steam locomotives like the 5AT which maintain […]
Adhesion and Sanding Adhesion It is vital that the tractive forces exerted by a locomotive’s wheels do not cause the available wheel/rail friction coefficient to be exceeded. For this reason, a locomotive’s “tractive effort” (TE) is limited by the adhesive weight on its driving wheels. Most steam locomotives were designed so that their TE was […]
5AT Route Availability The high route availability of a locomotive conforming to the size of the BR Class 5MT will not be confined to Britain alone. Due to the tight British moving structure gauge such a locomotive could run virtually anywhere in the world on standard gauge tracks taking 20-ton axle load, having thus a […]
5AT Power-to-Weight Ratio The power-to-weight ratio of any powered vehicle, whether car, aeroplane or locomotive, is not a fixed quantum, but varies throughout its speed range. At zero speed, the power output (by definition) is zero. As speed rises, power output will rise to a peak value, and will often decline as speed increases further. […]
5AT Operating Range Operating range is one of the most significant limitations facing the current fleet of heritage locomotives that operate on UK main line. In a few cases, their range is increased by the addition of an extra water tank or tender, but most are limited to the capacity of tenders that were designed […]
5AT Operating Costs Wardale offers the following brief comment about the 5AT’s operating costs: Low operating cost will be a consequence of the locomotive’s high thermal efficiency, giving low fuel and water consumption, high reliability, giving low maintenance expense, and low lubricating oil consumption due to the extensive use of sealed roller bearings. (See also […]
Steam Tables Steam tables used to be (and may still be) published in the form of a small booklet listing values of steam temperature, pressure, specific volume (i.e. the volume of 1kg of steam at a given temperature and pressure), specific entropy, specific enthalpy against various input values, separate sets of tables being provided for saturated and […]
Entropy Draft Text Only – Readers’ suggestions and inputs are welcome When a car or locomotive runs or brakes, we say that the heat escaping from it is “lost”. The Second Law of Thermodynamics explains this by saying that “energy will tend to dissipate from a hot or high energy body to a cold or […]
5AT Reliability Dave Wardale offers the following observations about the level of reliability that can be expected from the 5AT: In its truest sense this means that locomotives will achieve the necessary reliability “on the road” with very little maintenance effort. Good reliability is of major importance because (i) in-service failures which disrupt other services […]
5AT Thermal Efficiency The terms “Drawbar Thermal Efficiency” and “Cylinder Efficiency” are defined on a separate “Thermal Efficiency” page of this website. In the Fundamental Design Calculations (FDC 1.3), Wardale calculates that the thermal efficiency at the cylinders (i.e. comparing indicated power output with heat input) at maximum drawbar power will be approximately 15% and […]
Anomalies in Thermodynamics Draft Text Only – Readers’ suggestions and inputs are welcome Thermodynamics is not an easy subject to master and there are many instances where it defies intuitive judgement. The following examples are offered by way of enlightenment and perhaps education: Steam viscosity: it is intuitive knowledge that liquids become less viscous as […]