THE DESIGN OF AN OIL ENGINE. 39 
In place of a long suction and delivery stroke the two strokes are very sharp and 
quick, the plungers being idle the rest of the time. 
Now referring to the plan of the fuel valve it will be seen that this valve 
really is a double valve. The air for injection has one seat and the fuel comes 
through another seat. The lift of the fuel plunger should be timed to act with the 
opening of these two valves so that the fuel will be delivered by the pump directly 
into a stream of moving injection air. In this way the system can take care of any 
grade whatever of fuel. It has been pointed out that the trouble with most fuel 
valves is that the fuel is delivered to the fuel valve and allowed to come to rest, and 
then the air has to get in and around the fuel so as to deliver it in small portions 
and not asa whole. This design of fuel valve absolutely does away with any diff- 
culty along this line. 
Objection may be made to the care needed in timing the two elements—the 
fuel pump and the fuel valve. No reply is needed to such an argument. It is 
no more difficult than to time the spark on a gas engine. Another feature of the 
fuel valve is that the fuel starts after the air has started, and stops while the air 
valve is still open. The result is that the fuel valve should give no trouble with clog- 
ging—it is cleaned by air after each delivery stroke. 
Attention is called to the fuel heating tank. Here the fuel is heated by means 
of a coil of steam pipes within a tank. By this means a heavy, sluggishly moving 
fuel may be made to flow as freely as the present gas oil. The result is a saving 
of 50 per cent incost. With the particular type of fuel valve shown, no trouble 
should be experienced in getting this fuel too hot, beyond gasifying it, which would 
give an unequal action of the engine if carried to excess. 
All engines at present used in the United States submarines are said to use 
this comparatively high-priced gas oil. The engines shown in this design will run 
from the start on any grade of fuel, and it is thought that no other design of ma- 
rine oil engine will do this. The author is pleased to state that an engine has actu- 
ally been operated in this manner on low-grade California oil. 
STARTING. 
In the paper on “The Thermodynamics of the Marine Oil Engine” a great deal 
was said about the use of steam for starting the oil engine. There is no question 
about the advantage of steam in connection with the oil engine. At least the 
author has studied the matter from all viewpoints and can find no fault with the use 
of steam. Under these circumstances it is no more than right that some considera- 
tion be given to the type of steam generator which would give satisfaction in this 
service. 
The steam generator must have a large water body. There is one disadvantage 
to this—that it will take a considerable time to get this water body up to the de- 
sired temperature. This is true, but we are not handling a toy or quick-acting 
device. This type of engine is designed for actual service conditions seven days in 
the week. By this is meant that the engine is designed to be kept ready for use 
