What is meaning of steering gear unit system as per SOLAS ?

“Steering Gear Power Unit” means as per SOLAS :

(i)  In the cause of electrical steering gear, the electric motor and its associated equipment;
(ii) In the case electro-hydraulic steering gear the electric motor, its associated electrical equipments and connected pumps ;and
(iii) In the case of steam hydraulic or pneumatic hydraulic steering gear, the driving engine and connected pump; 

 You may also know:

“Steering Gear Control System” means the equipment by which orders are transmitted from the navigating bridge to the steering gear power units, steering gear control system comprise transmitters, receivers, hydraulic control pumps and their associated motors, motor controllers, piping and cables.

Points to ponder regarding Steering Gear-

  1. Every ship shall be provided with main steering gear and auxiliary steering gear, which shall be so arranged that the failure of one will not render the other in operative.
  2. The steering gear components and the rudder stock shall be designed and constructed to withstand with an adequate factor of safety, the maximum working stresses to which they may be subjected. Any bearings for such essential components shall be permanently lubricated or provided with lubrication fitting.
  3. The design pressure for steering gear components and piping subject to internal hydraulic pressure shall be at least 1.25 times the maximum working pressure anticipated when the steering gear is operating taking into account any pressure which may be existing in the low pressure side of the system. Fatigue criteria, taking into account pulsating pressure due to dynamic loads, shall be taken into account for the design of piping and components if the Chief Surveyor with the Government of India considers it appropriate.
  4. Relief valves shall be fitted to any part of the hydraulic system which can be isolated and in which pressure can be generated from a power unit or from external forces. The pressure at which relief valves operate shall not exceed the design pressure. The valve shall be of adequate size so as to avoid an undue rise in pressure above the design pressure.
  • The main steering gear and rudder stock shall-
  1. be of strength sufficient to steer the ship at maximum ahead service speed.
  2. be capable of putting the rudder over from 35 degrees on one side to 35 degrees on the other side with the ship running ahead at maximum service speed and, under the same conditions, from 35 degrees on either side to 30 degrees on the other side is not more than 28 seconds.
  3. be operated by power if necessary to meet the requirements of clause (b) and in any case when the diameter of the rudder stock in way of the tiller is required to be greater than 120 millimeters excluding additional strengthening for navigation in ice, and
  4. be designed so that they will not be damaged at maximum astern speed.


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