Chapter 21. -OTHER AUXILIARY EQUIPMENT 



SOCKET RING 



TURN 

 COMPONENT 



83.82 

 Figure 21-3.— Thrust and turning components 

 in hydraulic motor operation. 



The development of this type of steering gear 

 was prompted primarily by the large momentary 

 electric power requirements for electromechan- 

 ical steering gears— particularly for ships of 

 large displacement and high speed, with at- 

 tendant increased rudder torques. 



Electrohydraulic steering gears in use in- 

 clude various types of equipment. Some ship- 

 board installations have double hydraulic rams 

 and cylinders; others have single-ram arrange- 

 ments. (See figs. 21-4 and 21-6.) 



STEERING GEAR ARRANGEMENTS. -Only 

 the pump of the previously described electro- 

 hydraulic transmission is used in electrohydrau- 

 lic steering gears. Axial-piston variable dis- 

 placement pumps are used inmost installations; 

 radial-piston pumps are used in some. 



The pumps are connected by piping to the 

 ram cylinders of the steering gear. Two pipes 

 from each pump are united at a main transfer 

 valve. The transfer valve is a multiported 

 valve which permits the ram cylinders to be 

 connected to either pump while the pipes from 

 the other pump are connected for bypassing. 



Various methods are used for connecting the 

 hydraulic rams to the tiller. The arrangements 

 depend on the design and on the space available 

 for the installation. Two common arrangements 

 are shown in figures 21-4 and 21-6. 



Typical cruiser steering gear installations 

 include two rams set fore and aft, one on either 

 side of the rudder stock. The rams operate the 

 rudder through a double yoke tiller fitted with 

 sliding blocks. 



The gear illustrated in figure 21-6 is typical 

 of those installed on destroyers. The installation 

 includes a single ram set athwartship. The ram 

 operates the rudder through a single yoke tiller 

 fitted with a sliding block. 



Some cruiser steering gear installations have 

 two rams set fore and aft but located forward 

 from the rudder stock (fig. 21-4). The rams are 

 connected to the tiller by connecting links and 

 pins. Some ships are equipped with twin rudders 

 and an independent steering gear for each 

 rudder. Carriers and auxiliary ships may have 

 any one of the above-mentioned steering gear 

 arrangements. 



PRINCIPLES OF OPERATION.— Regardless 

 of the type of equipment (double ram or single 

 ram, axial pump or radial pump) included in 

 electrohydraulic steering installations, the prin- 

 ciples of operation are basically the same. The 

 discharge volume and direction of flow from the 

 variable displacement pumps are controlled by 

 the operation of the tilting block in the pump. 

 This control is accomplished mechanically by 

 means of trick wheels in the steering gear 

 room, and by remote control from one or more 

 steering stations. 



Any movement, right or left, of the control 

 from any of the various steering stations places 

 the hydraulic pump on stroke and causes the 

 pump to supply liquid under pressure to the 

 hydraulic rams, resulting in a corresponding 

 right or left movement of the rudder. This 

 rudder movement actuates the follow-up gear 

 which in turn immediately acts to return the 

 pump control to neutral but does not accomplish 

 this until the assigned rudder position has been 

 attained. The rudder is held in the assigned 

 position by a hydraulic lock until another move- 

 ment is originated at the steering station. 



EMERGENCY STEERING SYSTEMS.-All 

 naval combatant and auxiliary ships equipped 

 with electrohydraulic steering gears are also 

 equipped with an auxiliary steering gear. This 

 emergency steering system generally consists 

 of a relief and shuttle valve, hand-operated 

 hydraulic pump, and the piping, valves, and 

 fittings necessary to complete the system. The 

 emergency equipment is installed in or near the 

 steering gear compartment. 



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