The governor and governor belt should now receive attention making sure that there are no loose points or nuts in the mechanism and that the governor belt is in good condition. Defective governor belts are dangerous through the possibility of over speeding. Slipping or oily belts not only increase the chances of fly-wheel explosions, but also cause a fluctuation in the speed which is not desirable especially in threshing, where good results are obtained only by a constant speed. Make sure that the safety lever works properly and shuts off the steam with a loose or broken belt. Test the governor valve stem for sticking or for rough shots that are likely to cause uneven running. Keep the governor well lubricated with light oil, and keep the oil off the belt as much as possible. Governor valve should be carefully tested for tightness and freedom.
The throttle valve must be absolutely steam tight for a leaking valve is a dangerous proposition especially in stopping the engine. It is generally arranged so that it can be reground with pumice stone or crocus powder and oil. If the valve is of bronze or brass do not use emery or carborundum for the particles will become imbedded in the soft metal and put it in a worse condition than ever. Pack the valve stem.
A leaking slide valve is the cause of much loss of power, and waste of coal, and as the leakage mingles directly with the exhaust, it often remains unknown until it has thrown away a considerable quantity of fuel. It is best detected by blocking the engine with the piston at mid-stroke and opening the throttle valve slightly. If the cylinder drain cocks are now opened, the leaking steam that escapes into the cylinder will be seen issuing from the drains. The leakage that passes into the exhaust will be seen escaping from the stack while it is practically impossible to have the valves absolutely tight at all times, the steam should not escape so rapidly that it roars through the openings. Leakage past the piston is another source of loss that can be detected by blocking the engine so that the piston is very near, one end of the stroke, with the valve opening one of the cylinder ports. Any steam that passes the piston will pass out of the exhaust. With an old engine it is likely that the cylinder is worn oval, or that the valve seat is grooved or uneven, in which case it will be necessary to rebore the cylinder and fit new piston rings or reface the valve seat. Broken piston rings are often the source of leakage, and if not replaced with new at an early date, are likely to destroy the cylinder bore as well. Broken rings generally make themselves known by a wheezing click when the engine is running.
The steam feed pump should be well lubricated with a good grade of cylinder oil and should be well packed around the piston rod especially at the water end. To guard against pump troubles a good strainer should be provided on the water suction line to prevent the entrance of sticks and dirt into the cylinder. Great care should be exercised in keeping the suction line air tight, for if any air escapes into this line no water will be lifted. Dirt under the valves is the cause of much pump trouble, as a very small particle of dirt will allow the water to pass in both directions through the valves. Leaking packing will also destroy the vacuum in one end of the cylinder. For the best results the pump should be run slowly but continuously, feeding a small amount of water at one time. This method of feeding allows the feed water heater to bring the water up to the highest possible temperature which reduces the fuel consumption and reduces the strains on the boiler. It is a bad policy to let the water get low in the boiler and then “ram” full of cold water in a couple of minutes. Attention should be paid to the check valve that is located between the pump and boiler. It should be kept clean and the valve kept tight and in good condition.
When the feed water is hard a boiler compound should be used to reduce the amount of scale in the boiler or soften it and make its removal easier. Scale of 1
16 inch thickness will decrease the efficiency of the boiler by 12%, and this loss increases rapidly with a further increase in the thickness of the scale because of its insulating effect on the tubes. Soft sludges such as mud and clay may be removed by-blowing off or by the filtration of the water before it is pumped into the boiled. Lime and magnesia which form flint-hard deposits, require chemical treatment such as the addition of sodium phosphate, etc. In any case, the deposits waste heat and increase the liability of burning out tubes or bagging the sheets.
Buffalo Marine Motor.
A solution that has given good results with waters containing lime, consists of 50 pounds of Sal Soda and 35 pounds of japonica, dissolved in 50 gallons of boiling water. About 1
40 quart is fed into the boiler for every horse-power in 10 hours, the solution being mixed with the feed water. Kerosene has been used a great deal to soften scale, and gives good results if not fed in quantities to exceed 0.01 quart per horse-power day of 10 hours. An excess of kerosene is to be guarded against for it is likely to accumulate in spots and cause bagged sheets or burn outs.