Editing Balao-class submarine (section)

=== Engines ===

The propulsion of the ''Balao''-class submarines was generally similar to that of the preceding ''Gato''-class. Like their predecessors, they were true [[diesel-electric]] submarines: their four [[diesel engine]]s powered [[electrical generator]]s, and [[electric motor]]s drove the shafts. There was no direct connection between the main engines and the shafts.

[[File:General Motors Model 16-248 V16 diesel engine.jpg|thumb|left|[[Electro-Motive Diesel|General Motors]] [[Cleveland Diesel Engine Division|Cleveland]] Model 16-248 diesel engine]]
[[File:Opposed piston engine 1.jpg|thumb|left|[[Fairbanks-Morse]] Model 38D{{frac|8|1|8}} diesel engine]]

''Balao''-class submarines received main engines from one of two manufacturers.
[[Electro-Motive Diesel|General Motors]] [[Cleveland Diesel Engine Division|Cleveland Model]] 16-278A V-type diesels or [[Fairbanks-Morse]] [[Fairbanks Morse 38 8-1/8 diesel engine|38D 8-1/8]] nine-cylinder [[opposed-piston engine]]. The [[Electro-Motive Diesel|General Motors]] [[Cleveland Diesel Engine Division|Cleveland Model]] 16-248 V-type as original installations, while boats from {{USS|Sand Lance|SS-381|2}} onward received 10-cylinder engines. Earlier General Motors boats received Model 16-248 engines, but beginning with {{USS|Perch|SS-313|2}} Model 16-278A engines were used. In each case, the newer engines had greater [[Engine displacement|displacement]] than the old, but were rated at the same power; they operated at lower [[mean effective pressure]] for greater reliability. 
<ref>{{cite book |last=Alden |first=John D. |title=The Fleet Submarine in the U.S. Navy: A Design and Construction History |date=1979 |publisher=Naval Institute Press |isbn=0-85368-203-8 |pages=90, 210–212}}</ref> Both the Fairbanks-Morse and General Motors engines were [[two-stroke cycle]] types.<ref>{{cite press release|last=Stern|first= Robert C. |date=2006|title=Gato-Class Submarines in action|url=https://quietwarriors.files.wordpress.com/2014/02/squadron-signal-4028-gato-class-submarines1.pdf|publisher= Squadron Signal Publications|access-date=2023-09-17}}</ref>

Two submarines, {{USS|Unicorn|SS-429|2}} and {{USS|Vendace|SS-430|2}}, were to receive [[Hooven-Owens-Rentschler]] (H.O.R.) diesels, which proved unreliable on previous classes, but both boats were cancelled.

Two manufacturers supplied electric motors for the ''Balao'' class. [[Elliott Company]] motors were fitted primarily to boats with Fairbanks-Morse engines. [[General Electric]] motors were fitted primarily to boats with General Motors engines, but some Fairbanks-Morse boats received General Electric motors. [[Allis-Chalmers]] motors were to be used in SS-530 through SS-536, but those seven boats were cancelled before even receiving names.<ref> {{Cite web|url=https://maritime.org/doc/fleetsub/elect/chap2.php/|title=Submarine Electrical Systems|website= www.maritime.org/}}</ref>

Earlier submarines carried four high-speed [[electric motor]]s (two per shaft), which had to be fitted with reduction gears to slow their outputs down to an appropriate speed for the shafts. This reduction gearing was very noisy, and made the submarine easier to detect with [[hydrophone]]s. Eighteen late ''Balao''-class submarines received low-speed double [[Armature (electrical engineering)|armature]] motors which drove the shafts directly and were much quieter, but this improvement was not universally fitted until the succeeding {{sclass|Tench|submarine|4}}.<ref>Bauer and Roberts, p. 275</ref> The new [[direct drive]] electric motors were designed by the [[Bureau of Ships]]' electrical division under Captain [[Hyman G. Rickover]], and were first equipped on {{USS|Sea Owl|SS-405|2}}.<ref>Friedman through 1945, pp. 209-210</ref> On all US World War II-built boats, as the diesel engines were not directly connected to the shafts, the electric motors drove the shafts all the time.