30 THE DESIGN OF AN OIL ENGINE. 
valve would be available. This does not seem desirable or necessary. By control- 
ling the application of heat to the fuel it seems very reasonable to believe that any 
grade of fuel will be satisfactory, and the only mechanical problem will be to design 
a fuel pump to handle the fuel and a fuel valve to produce the spray. 
FUEL PUMP. 
In his experimental engine the author had means for pumping up a fuel pres- 
sure, by moving the block, which carried the lower end of the pump connecting 
rod along a slide oscillated by an eccentric. When the engine was at rest, by 
moving this block from the position of no motion to the position of full stroke of 
the pump, a movement of the pump plunger was obtained. It was found that a 
slow motion of the plunger did not produce as good results as a very quick and 
sharp motion. This suggested that more ideal conditions could be obtained by de- 
signing a pump in which the fuel would be delivered by a blow on the plunger like 
that which would be given by the impact of ahammer. The only practical reason 
for this is that such a blow will start the check valves better. In a way the check 
valve is moved by the stream of fluid in the pipes, and the more rapid the motion of 
the fluid the more perfect is the action of the valves. No doubt the trouble which 
the author experienced was due to imperfect mechanical details, but if this modifi- 
cation will enable a more imperfect construction to produce the desired result it 
cannot be out of place in a perfect mechanical device. 
Besides the advantage in the action of the check valves resulting from this de- 
sign, there is a further gain. This gain is shown by the figures on Plate 19. In 
spraying a heavy oil from the present type of fuel valves considerable difficulty 
seems to be encountered from the fact that the fuel is delivered to a fuel-receiving 
chamber and then picked up from this chamber by means of the injection air. 
With a light fluid fuel this difficulty is not noticed. As the oil becomes more heavy 
and sluggish this difficulty increases. The sheet referred to explains the situation. 
In the first two figures the heavy black line shows the duration of the delivery 
stroke of the fuel pump. This would be for full stroke or the full-power condition. 
The short, light space at the top shows the duration of the opening of the fuel valve 
into the cylinder. From this it becomes at once evident that the fuel is delivered to 
the fuel valve and there comes to rest. From this position of rest it must be again 
put in motion and torn apart by the action of the injection air. There is a certain 
inertia to the oil and this inertia is greatly augmented in the case where the fuel has 
a high viscosity. This type of fuel valve is that proposed by Geo. B. Brayton and 
patented by him. In these figures the time of a complete cycle of the engine is 
shown by the full circle of 360 degrees. The various events of the cycle are shown 
in the figures. The next figure shows the method which is proposed by the author. 
As will be seen in the consideration of the fuel pump, the two strokes of the pump 
are of short duration and the rest of the time the pump is idle. The theory of this 
method of fuel injection is to co-ordinate the operation of the fuel valve and the 
