USS Liberty Mechanical Systems
To a great extent, USS Liberty's engine room mechanical systems were the same as originally installed on the WW2 Victory class merchant ship, SS Simmons Victory, upon which she was built.  But during Simmons Victory's conversion, many compartments and facilities were added or modified which required expansion or modification of her auxiliary mechanical systems and electrical power generators. All of this was documented by Liberty's Engineering Officer, Lt George Golden, in a set of mechanical systems schematic drawings.
(9 megabyte PDF document opens in new window and may take more than a minute to download)
The schematic drawings show new electrical power generation equipment consisting of three 500KW generators (steam turbine driven), with one dedicated solely to the ship's vast array of electronic equipment. Also, an emergency 100KW generator (diesel motor driven) was housed in the forward deck house -- all added during the ship's conversion to USS Liberty.[1]
Engine room primary equipment appears virtually unaffected by the conversion; it consisted of two Combustion Engineering company double-casing, sectional header-type boilers capable of operating at a maximum super-heated steam pressure of 465 pound per square inch, and one General Electric company cross-compound steam turbine capable of producing 8500 horsepower and propelling Liberty in excess of 17 knots speed.[1][2]
(Click on image for enlarged view; use browser back-button to return.)
Victory Ship Engine Room
  Victory Ship Engine Room
(USS Liberty was a converted Victory Ship)
[2] United States Maritime Commission historical records show that SS Simmons Victory, hull number 182, was a VC2-S-AP3 type Victory Ship. This type Victory ship had two high-pressure steam boilers and an 8500HP compound steam turbine.