Steam Waste. The steam necessary to do the work in the cylinders required in hauling a train of a given tonnage at a given speed is very often augmented by wastes of various kinds, which should be reduced to a minimum. These wastes may be due to improper care of the engine, either on the road or in the roundhouse or both, to improper manipulation when on the road, and to the use of bad water. Still other wastes may be due to high steam pressures and high rates of evaporation.
Waste from Piston and Valve Rods. The most common sources of leakage are steam blows. When these occur into the atmosphere from the piston and valve rods, it is quite noticeable, and they may constitute a very great loss, especially where high steam pressures are employed. Besides being a direct loss, under certain conditions the presence of the steam in the air may obstruct the view ahead, making operation more hazardous. Anything which causes undue vibration of the piston and valve rods will eventually cause leaky packing. For this reason the guides should be kept in proper adjustment to prevent vertical movement of the crosshead. In engines using piston valves with inside admission, there will ordinarily not be trouble by steam leaks around the valve rods.
Waste from Cylinder and Valve Piston Packing. It sometimes happens that losses occur due to steam blowing past the packing rings of the cylinder piston or the valve. Indicator cards will usually show such leaks, but as a rule they can be detected by the sound of the exhaust. Such steam blows are more difficult to locate in compound than in simple engines. A practical method of detecting steam blows past the cylinder and valve piston packings consists in blocking the engine in different positions of the crank and noting the presence or absence of steam at the cylinder cocks or stack.
Waste Due to Priming. The use of water which causes priming eventually causes steam blows. Priming is frequently so serious that the whistle cannot be blown without closing the throttle in order to reduce the water level in the boiler. In aggravated cases where water is carried over into the cylinders, it not only endangers the cylinder heads, etc., but sooner or later injures the piston and valve packing, piston and valve rod packing and valve seat, causing leaks and serious waste of steam.
Waste from Safety Valve. Another common waste of steam occurs through the safety valve, caused oftentimes by a careless manipulation of the fire. Such losses occur most frequently when the locomotive is standing on a siding or coasting. This may seem to be a small matter, but if we consider a road using 1000 locomotives per day and each fireman permitting the safety valve to blow on an average of 10 minutes per day, the amount of steam wasted daily would approximate 1,000,000 pounds, which would represent a waste of fuel per day of about 75 tons. Such waste can be reduced to a minimum by the intelligent manipulation of the injectors, dampers, and fire door.
Table of Contents; Page 170; Page 173; Index