HEAVY-OIL ENGINES FOR MARINE PROPULSION. 245 
Fourth. It would be interesting to know how the author arrived at his figures 
for annual repairs as between a steam plant and an oil engine plant, viz., $10,000 
for steam and $2,000 for oil. It is absolutely necessary in heavy oil engines to have 
the most excellent workmanship, for instance, and nothing but ground joints must 
be used. Should any trouble be experienced with these, how far would $2,000 go 
in repairing an 8,300 horse-power plant? It should be noted, also, that in case of 
steam, there are two line shafts, stern bearings and stuffing-boxes, propellers, etc., 
while in the oil plant there are three, giving opportunity for trouble to the extent 
of one-third more than with the steam plant. 
Mr. CLInton H. Crane, Member:—It is rather a thankless task to take the 
position of a knocker, but the Diesel oil engine, or the Diesel engine to burn oil or 
coal dust, has been before the engineering profession for more than fifteen years. 
During that time we have seen what has happened to the turbine. Almost all that 
we have read or heard about the oil engine has been what somebody says that some- 
body else did. The writer speaks of engines with a capacity of 2,000 horse-power 
per cylinder having been built. He does not state when or where. 
I think there undoubtedly exists in the mind of any engineer the opinion that 
the difficulties, when you come to deal with 500 pounds pressure, are very greatly 
increased. ‘The limit on the size of a reciprocating engine seems to me not to bea 
question of horse-power, but a question of maximum pressure. The strength of 
cranks, the amount of crank pin bearing, the strength of connecting rods, are all 
determined, and must be determined on this question of maximum pressure. That 
is an inherent disadvantage which any engine with a maximum pressure as great as 
shown by this oil engine diagram labors under. 
In the 4-cycle type, which the author says is more economical, one stroke in 
four is a power stroke. Therefore ina steam engine of the same cylinder capacity, 
the same power can _be produced with one-quarter of the mean effective pressure. 
It seems to me that the oil engine has so many possibilities in the smaller field 
that the people who put forth the claim for the use of the oil engine on battleships, 
for large sized steamers, are hurting their own development. We know what a gas 
or gasoline engine has done up to 300 horse-power and even in those relatively small 
powers we have a multiplicity of cylinders. With anything like a large installation, 
with an oil engine, the multiplicity of cylinders and the care of those cylinders is 
bound to increase. 
Another point which the writer of this paper has not enlightened us on are the 
points where we may look for trouble. In talking to users of the smaller sized 
Diesel engines, when you finally pin them down to it, there is some little piece here, 
there is some little piece there, that has got to be renewed once a month, or that has 
got to be taken out and cleaned every four or five days—all those things are neces- 
sary to a new development, but they are things which, as engineers, we should be 
informed of by the writers of such papers. 
If the oil engine is to take the place of the steam turbine, a great deal of develop- 
