Explained : All electrical steering gear system

  • The rudder of the steering gear system is driven by a DC motor. 
  • The power for the rudder motor is supplied by a DC generator for controllable, output voltage. The DC generator is driven by a single-speed, three-phase squirrel cage induction motor. 
  • The speed and direction of the rudder motor are varied by varying the applied voltage. The alternating current from the main power source is transformed to lower voltage and rectified to supply the motor field poles. The output of the generator is varied by varying the generator field current and direction using a rheostat.

  • As the direction is varied, the applied currents supplied to the rudder motor changes the direction accordingly.
  • Two rheostats are connected to form a Wheatstone bridge circuit. The two rheostat contacts, namely the wheel order rheostat contact and the rudder contact are connected to the two ends of the generator field coil.
  • When the steering wheel is in midship position, the two rheostat contacts are in the same position and no current flows between them. 
  • Now, the steering wheel is turned to port. This causes the wheel order rheostat contact to move up, from the centre position.
  • Due to the difference in voltages between the two contacts, the current will flow through the generator field coil.
  • The generator develops power and supplies it to the data motor, which turns the rudder to the port side.
  • As the rudder turns, the rudder rheostat contact moves up, and as the rudder reaches the required angle, the rudder contact will reach the wheel order contact position.
  • The current flow to the generator field coil will stop and the Rudder motor will also stop turning the rudder. The steering field is turned to midship. This will move the wheel order contact to a midship position.
  • The current to the generator coil will flow in the opposite direction on the rudder motor turns counterclockwise, turning the rotor to the opposite side.
  • As the rudder reaches the midship position, the rudder contact reaches the position opposite to the wheel order contact. The current flow to the generator field coil stops.
  • Hence, the generator output voltage to the rudder motor also stops. There rudder stops at the midship position. The same process continues for all the wheel orders.

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