Chapter 21. -OTHER AUXILIARY EQUIPMENT 



BRAKE OPERATING ROD 



DRIVING NOT 

 3 \ LINK 



PEDESTAL SECURED 

 TO DECK i 



RUDDER^ 

 YOKE 



^ BRAKE BAND 

 'RUDDER STOCK 



Figure 21-5. —Right-and-left screw steering gear. 



TRANSMISSION SHAFT 

 FROM STEERING ENGINE 



47.140X 



ELECTRICAL SYSTEMS. -Steering gear 

 control systems of the electrical type are divided 

 into two general types— the direct current pilot 

 motor type and the alternating current syn- 

 chronous transmission type. The direct current 

 pilot motor type is no longer used on new 

 construction. 



The direct current pilot motor type of 

 remote control consists of a small reversible 

 direct current motor which is connected through 

 the differential gear to the control shaft of a 

 variable displacement hydraulic pump. The con- 

 trol of the pilot motor is effected by means of a 

 magnetic contactor control panel located adja- 

 cent to the motor and through master controllers 

 located at remote control stations. The motor 

 is equipped with a magnetic brake which promptly 

 stops and holds the motor when the master 

 controller is returned to the neutral position. 



The alternating current synchronous trans- 

 mission type of remote control consists of 

 interchangeable receiving and transmitting units 

 which are, in reality, small wound rotor in- 

 duction motors with interconnected three-phase 

 rotor windings; their stator windings are con- 

 nected to the same alternating current supply. 

 When the transmitter rotor is turned, the re- 

 ceiver rotor turns at the same speed and in 

 the same direction. 



The transmitters are located in steering 

 stands at remote control stations such as the 

 pilot house, conning tower, central station, 

 etc., and are mechanically connected through 



gearing to the wheels. A transmitter at one of 

 the remote stations is electrically connected to 

 a receiver in the steering room. Where more 

 than one remote steering station is provided, 

 as on cruisers and carriers, a switch is pro- 

 vided for selecting the desired control station. 

 Indicating lights are provided on the steering 

 stands and at the selector switch to indicate the 

 selected circuit and the power available. 



The receiver is connected to the control shaft 

 of the variable displacement hydraulic pump 

 through a differential. On large hydraulic units 

 where the torque required to stroke the pump is 

 greater than the torque that can be exerted by 

 the receiver, the stroke is controlled through an 

 auxiliary hydraulic servosystem. In installations 

 involving the use of a servosystem, the syn- 

 chronous receiver actuates a pilot valve which 

 controls the flow of oil, under pressure, to 

 and from a power cylinder. The direction and 

 amount of motion of the power piston controls 

 the stroke of the main pump which actuates the 

 rudder. 



Electrical control circuits from the trans- 

 mitter selector switch (from the pilot house 

 selector switch in the case of destroyers and 

 auxiliary vessels) to the steering gear com- 

 partment are installed in duplicate. Drum-type 

 selector switches, one in the steering room and 

 one located at the terminus of the duplicate run 

 of control circuits, are provided for selecting 

 the port or starboard cable. When independent 

 synchronous receivers are provided for each 



525 



