38 THE DESIGN OF AN OIL ENGINE. 
enough to take the pressure off the cams and yet not enough to interfere with the 
valve action. 
The start of this engine is obtained by this same lever. The tappet rod which 
operates the starting valve is lifted by a further motion of this same lever which will 
open all the starting valves. This sets the engine in operation, and the valve timing 
determines the proper direction of rotation. This is done by having a longer 
and different shaped cam acting on the starting valve tappet. This will be wasteful 
of starting energy, but the waste will not be excessive and the desired effect will be 
an instantaneous response to the reverse lever. 
The desired operation of the admission valve is obtained by means of varying 
the timing of the admission valve cam and by making the valve automatic as far as 
opening is concerned, and mechanically operated as far as closing is concerned. This 
is done by having the valve cam simply release the admission valve. When this is 
done the valve stays open as long as the suction stroke is in progress. A partial 
suction stroke may be obtained by advancing the admission valve cam. In this way 
the valve opens, but not until the suction stroke of the piston begins. On the other 
hand, when the valve cam completes its operation the tappet rod falls and closes the 
admission valve. The author is of the opinion that no novelty exists in this method 
of operation. 
FUEL AND FUEL FEED. 
This is a most important matter and this design is unquestionably superior to 
the submarine engines at present installed in the United States submarines. If we 
divide the method of fuel feeding into two classes we shall have the present class 
and the proposed class. We may call these two classes the Diesel type and the Went- 
worth type. As far as the author knows he is the first to propose this modification. 
Plate 19 shows this difference. In the Diesel engine the operation of the fuel pump 
is slow. The plunger is practically moving all the time, but the stroke is so short 
that the speed of the plunger is very slow. The author has found by actual experi- 
ence that a fast-moving plunger will give better results than this slow-moving 
plunger. The result is the fuel pump, as shown in detail. The feature of this 
pump is a floating piston. This piston or plunger is lifted in the delivery stroke 
by a lever operated by a cam. The plunger is returned by the springs at the bot- 
tom of the plunger. The plunger is at all times kept against the lever by means 
of the spring. The motion of the lever determines the stroke of the plunger, and 
the movement of the lever is controlled by an eccentric shaft. With full eccentric- 
ity of the shaft up, the lever is held so that the cams clear and no fuel is delivered. 
With the shaft turned an angle of 180 degrees the maximum stroke of the plunger 
is obtained. Any desired position may be obtained for the shaft between these two 
extreme positions and so the amount of fuel delivered may thus be governed. The 
feature of this pump is not only to deliver exactly the fuel required, but to deliver 
this particular amount and at just the moment it is needed. By varying the posi- 
tion of this set of cams the action of the fuel pump may have a different timing. 
