The word “indicated” comes from the use of “Indicator Diagrams” that before the electronic era were mechanically plotted to indicate the variation in steam pressure inside a cylinder against the piston position as it sweeps through the piston over the length of its stroke. Separate diagrams for both ends of the cylinder were usually being […]
Drawbar Power The power output at the drawbar of a locomotive, the drawbar being the coupling between the locomotive and the train that it is hauling. Drawbar power used to be measured by attaching a “dynamometer car” between the locomotive and its train. A dynamometer car incorporates a number of measuring devices including a calibrated spring for […]
Tractive Effort “Tractive effort” (TE) is the force applied by a locomotive for moving itself and a train. Tractive effort or tractive force is measured in kilo-Newtons (kN) or pounds force (lbf) where 1 kN = 228.4 lbf. As with “power”, there are different methods of measuring tractive effort: Drawbar tractive effort – the force […]
Power-to-Weight Ratio The Power-to-Weight ratio of a car is a measure of its ability to accelerate. A steam locomotive’s ability to accelerate is governed by its the ratio of its “power : total train weight” ratio and by its adhesive weight and adhesion coefficient (ignoring resistance factors). The Power-to-Weight ratio of a steam locomotives is […]
Locomotive Power Power is defined as “the rate of doing work”. Common units of power in the metric system are Watts (W), kilowatts (kW), Megawatts (MW) and Gigawatts (GW), where 1 Watt = 1 Joule per second = 1 Newton-metre per second. Alternative units of measurement are calories per second and kilo-calories per hour (1 […]