Chapter XI: Appendix: No. 2

THE HORNSBY-AKROYD OIL ENGINE AND GENERATOR.

(See also Artillery Notes, No. 12.)

=The engine.=—This is a horizontal, single-acting, single-cylinder kerosene engine, having a flyball governor and operating on a four-stroke cycle. This cycle consists in turn of the explosion on the first outstroke, the expulsion of the products of the explosion on the following instroke, the intake into the cylinder of a mixture of air and oil vapor on the following outstroke, and the compression of this explosive mixture on the next instroke. This cycle therefore requires two complete revolutions of the crank shaft for one complete set of operations.

On one side of the cylinder near the closed end is a valve box containing two valves, the air-inlet valve and the exhaust valve. The air-inlet and the exhaust valves are actuated by separate levers, each lever being moved by a cam mounted on a horizontal shaft, driven by the crank shaft through worm gearing. This horizontal shaft makes but one revolution while the crank shaft makes two; thus the air-inlet and the exhaust valves are each opened once every two revolutions of the flywheel.

At the back of the cylinder, in prolongation of its axis, is a cast-iron box called the vaporizer, which is always open to the cylinder. Before starting the engine this vaporizer must be heated by an external lamp, so that it will vaporize the oil when it is first pumped into it. After the engine has started running, the lamp is no longer required, as the vaporizer is kept at a sufficient heat by the internal explosions.

A small oil pump, worked by the air-valve lever, draws oil from the oil tank under the engine and forces it into the vaporizer at the proper time. The oil, on its way from the pump to the vaporizer, passes through a valve box attached to the vaporizer; this valve box has two valves in it, a horizontal one, kept closed by a spring which the oil forces open as it goes into the vaporizer; the other, a vertical one, also kept closed by a spring. Should the engine run too fast, the governor opens this latter valve and allows some of the oil to flow back to the oil tank through the waste pipe. This valve can also be opened by turning the little regulating handle, which will stop the supply of oil to the vaporizer and thus stop the engine.

INSTRUCTIONS FOR WORKING.

=Frosty weather.=—If there is danger of freezing, on shutting down drain the water from the circulating pipes and cylinder jacket, and valve box if water-jacketed; otherwise they may burst or crack.

=Caution.=—Before starting, see that the cocks which admit water to the water jacket of the vaporizer valve box are open; that the cock on the main water pipe from the bottom of the water tank is open; that the water in the tank is above the upper circulating pipe; that the drain cock is closed; and that the oil tank is filled with kerosene. _Gasoline must not be used with this engine._

=Heating the vaporizer.=—Open the relief cock on top of the engine cylinder. Place the lamp on the stand under the vaporizer; fill the lamp with oil by means of the filling pipe till the oil is 1 inch below the pipe; and put a piece of wick into the cups which are formed around the pipes. These wicks, which should consist of a piece of ordinary asbestos packing, will last for several weeks. Place the lid of the vaporizer cover crosswise on the cover to allow the escape of heated gas and air.

A little alcohol or kerosene should be poured into the cup under the coil and lighted. The cups may be filled with kerosene by closing the air-escape valve and working the air pump. The pressure forces oil out through the vapor nozzle and it will run down into the cups. When this is nearly burned out pump up the reservoir with air by the air pump. Oil will issue from the small nozzle and give a clear flame. When it is desired to stop the lamp, turn the thumbscrew on the reservoir filling nozzle to let the air out. Should the nozzle become choked it should be cleaned with the small needles for that purpose.

The heating of the vaporizer is one of the most important things to be attended to, and care must be taken that it is hot enough at starting. The attendant must see that the lamp is burning properly and that a good clear flame is given off for from 5 to 10 minutes, according to the size of the engine. If, however, the lamp is burning badly, it may take longer to become heated sufficiently. It is important that this should be carefully attended to, for though the engine may start, if the vaporizer is not as hot as it should be the engine will run badly and perhaps soon stop altogether. Failures of engines to run properly can in most cases be traced to this source.

No time should be lost in starting the engine after the vaporizer has been sufficiently heated, as the engine may not run satisfactorily if the vaporizer is allowed to cool after heating it. The lamp should be left burning a few minutes after starting.

=Oiling the engine.=—Oiling the engine should always be done during the heating-up of the vaporizer.

See that the oil cups on the two main crank shaft bearings are fitted with proper wicks and filled with oil. Adjust the lubricator on the large end of the connecting-rod and oil the small end which is inside the piston.

Oil also the following: The bearings on the horizontal shaft and the skew gearing, the rollers at the ends of the valve levers and their pins, the pins on which the levers rock, the governor spindles and joints and the bevel wheels which drive the same, and the joints that connect the governor to the vertical valve of the overflow. For such bearings none but the best engine oil should be used.

It is necessary that a suitable oil should be used for lubricating the cylinder, and unless such an oil be used for this purpose the engine may run badly and perhaps stop altogether. Under no circumstances must a thick cylinder oil be used, and the oil must not be used over again on the piston. Do not use ordinary lubricating oil. A high-grade gas-engine oil especially suited to this engine should be used and the piston should be kept flooded with it.

=Starting the engine.=—Throw the hand lever to “To start.” Turn the small crutch-handle regulator Y to the position “Shut” and work the pump lever up and down until oil is seen to pass the overflow freely. Turn the regulator back to “Open,” work the pump lever up and down a few strokes. Vapor should issue with some force from the relief cock on the cylinder. This indicates sufficient heat. Close the relief cock and pump a few strokes. Man the flywheel and start the flywheel backward, using the weight of the body if necessary, bringing the piston up against compression as sharply as possible, and then release the wheel, when an explosion should take place and the engine start forward. As soon as the engine has sufficient speed to carry it past a full compression, throw the lever to “To work.” When full speed is obtained, cut down the pump stroke to correspond to the load, open the oil feeders, and go over the engine carefully, seeing that the cylinder oil feed is working.

=Oil pump.=—When the cylinder is working at its full power the distance between the round flanges on the pump plunger should be such that the hand gauge (supplied with the engine, and to be found in the tool box) will allow the part stamped “1” just to fit in between the flanges; if at any time the positions of these flanges be altered they can be readjusted to this gauge. The other lengths on the hand gauge are useful for adjusting the pump to economize oil. When running on a medium load, use length marked 2; on a light load, use length marked 3. See that the pump packing is not too tight.

=Running the engine light.=—When the engine is to run light—that is, with no load or with a light load—it is best to alter the stroke of the pump to the amount of oil that will keep the engine running. This amount can be reduced so that the speed of the engine is a few revolutions under the normal, which will allow the vaporizer to get a small charge each time and keep it from cooling. The cock on the return of the water circulating pipe may be nearly closed to keep the cylinder warmer. These remarks do not apply when the load is intermittent and the engine is running light for a short time only.

=Air-inlet and exhaust valves.=—See that the air-inlet and the exhaust valves are always working properly and drop onto their seats. They can at any time, if required, be made tight by grinding with a little flour of emery and oil.

To insure a good seat to the valves when the stems are expanded by heat the stems should clear the set-screws on the levers at least ¹/₁₆ inch when the air and the exhaust levers are clear of the cams. A greater clearance is undesirable, as it prevents the full opening of the valves.

If at any time the air-inlet or the exhaust valves appear to be opening or closing at the wrong time, take off the nut on the end of the lay shaft which holds the skew-wheel on and see that the chisel cuts on the shaft are opposite to one another. The lay shaft is coned where the skew wheel is fixed on and it is held on simply by friction, the nut being tightened against it.

Should it at any time become necessary to take out the crank shaft, always be sure that the skew-wheel gearing is put together so that the tooth marked “0” on the crank shaft skew-wheel fits in between the two teeth marked “0” on the oil-shaft skew-wheel.

=Vaporizer valve box and pipes attached to vaporizer.=—In this box there are two valves. The vertical one is regulated by the governor, and when the engine runs faster than its proper speed the governor pushes it down, thus opening it and allowing some oil to return to the oil tank. The horizontal valve in this box is a back-pressure valve. If at any time this valve is not working properly, vapor will be seen coming out of the overflow pipe; in this case the valve should be examined. By screwing off the outside cap the tail of this valve can be seen; if the valve is turned around a few times it will probably dislodge any dirt that may be under it; if, however, this does not stop the leakage the valve should be taken out for inspection.

If the horizontal valve and sleeves are taken out at any time, great care must be taken in replacing them to use the same thickness of jointing material as before or the distance the valve opens will be altered.

See that the pipe from the pump to the vaporizer valve box is inclined upward all the way from the pump. If this is not so, an air pocket will be formed in which a certain amount of air will be compressed upon each stroke of the pump. This will cause the oil to flow in slowly and not suddenly as it should. If the oil tank be emptied of oil at any time, air will get into the suction and delivery pipes of the pump and it will take some time before the oil going through the pump and pipes will be free of this air; for awhile thereafter, the engine will not work properly, as the air, by being compressed as the pump works, will interfere with oil being pumped in suddenly. It is best, if the oil gets below the filter in the tank, to work the pump by hand for about 10 minutes, holding the relief valve (on the vaporizer box) so as to get air well out of the pipes.

=To stop the engine.=—Turn the crutch-handle regulator to “Shut.” Close the automatic lubricator. If it is desired to stop the engine for a short time only, put the lamp back under the vaporizer to keep it hot.

=Setting the oil engine and the generator.=—The engine and generator should be so located that the distance from center to center of pulleys should be as nearly correct as possible when the generator is at the middle point of the base rails, so that the proper tension of the belt may be obtained within the limits of adjustment allowed by the rails.

The two pulleys should be accurately in line and the belt not too tight. The generator base should rest on a wooden frame to separate it from the concrete pier. Both engine and generator should be held firmly in position by anchor bolts.

For the generator bearings a quantity of the best dynamo oil is furnished; the commutator should be clean and smooth, and the brushes should fit the surface. The commutator should be cleaned occasionally with a little paraffin on canvas, and the brushes should be adjusted, so that when running at full load no sparking occurs.

All electrical connections should be firmly made and kept thoroughly clean. A cover should be kept on the generator when not in use. If the machine be damp it should be allowed to dry before running at full load.

=NOTE.=—A few new installations have been
supplied with 5-kw. gasoline electric sets, and future
installations will be similarly equipped. Wherever
installed, pamphlets on the care and operation of the
gasoline sets have been furnished, containing full
instructions for the guidance of those concerned.