Chapter 9-MACHINERY ARRANGEMENT AND PLANT LAYOUT 



and galley, as well as providing makeup water 

 for various fresh water cooling systems. 



HYDRAULIC SYSTEMS 



Hydraulic systems are used aboard ship to 

 operate steering gear, anchor windlasses, hy- 

 draulic presses, remote control valves, and 

 other units. 11 Hydraulic systems operate on the 

 principle that, since liquids are noncompres- 

 sible, force exerted at any point on an enclosed 

 liquid is transmitted equally in all directions. 

 Hence a hydraulic system permits the accom- 

 plishment of a great amount of work with re- 

 latively little effort on the part of shipboard 

 personnel. 



The medium used to transmit and distribute 

 forces in hydraulic systems may be a petroleum- 

 base product (hydraulic oil) or a pure phosphate 

 ester fluid. Phosphate ester fluid is more re- 

 sistant to fire and explosion than the petroleum- 

 base oil that was used in all hydraulic systems 

 until fairly recently. Phosphate ester fluid is 

 now used in aircraft carrier elevators, surface 

 ship missile systems, jet blast deflectors], 

 seaplane servicing booms, high pressure sub(- 

 marine systems, and all hydraulic systems 

 operating at pressures of more than 500 psi 

 in new construction and conversion surface 

 ships. 



METHODS OF PROPULSION 

 PLANT OPERATION 



The major engineering systems on most 

 naval ships are provided with cross-connections 

 which allow the engineering plants to be opera- 



l^Many hydraulically operated units are discussed in 

 chapter 21 of this text. 



ted either independently (split-plant) or together 

 (cross-connected). In cross- connected opera- 

 tion, boilers may supply steam to propulsion 

 turbines which they do not serve when the plant 

 is split. In split-plant operation, the boilers, 

 turbines, pumps, blowers, and other machinery 

 are so divided that there are two or more 

 separate and complete engineering plants. 



Cross- connected operation was formerly 

 standard for peacetime steaming, and split- 

 plant operation was used only when maximum 

 reliability was required— as, for example, when 

 a ship was operating in enemy waters in time 

 of war, operating in heavy seas, maneuvering 

 in restricted waters, or engaged in underway 

 fueling. However, the greater reliability of 

 split-plant operation has led to its increasing 

 use. At the present time, split-plant operation 

 is the standard method of underway operation 

 for most naval ships; cross- connected opera- 

 tion is used for in- port steaming but is rarely 

 used for underway steaming. 



On some ships the engineering plants can be 

 operated by a method known as group operation. 

 For example, the USS Forrestal. CVA 59, has 

 four separate propulsion plants. The two for- 

 ward plants (No. 1 and No. 4) constitute the 

 forward group and the two after plants (No. 2 

 and No. 3) constitute the after group. Although 

 each of these four plants is normally used for 

 the independent (split-plant) operation of one 

 shaft, the boilers in any one plant can be cross- 

 connected to supply steam to the turbines in the 

 other plant in the same group. While underway, 

 therefore, the boilers in the No. 1 plant can be 

 cross- connected to supply steam to the No. 4 

 plant, although they cannot be cross- connected 

 to supply steam to the two plants in the other 

 group. For in-port operation, any boiler can be 

 cross- connected to supply steam to any turbo- 

 generator and to all other steam-driven auxili- 

 aries. 



229 



