Marine Steering Gear Systems - Construction and Working

Marine Steering Gear Systems - Construction and Working
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A Steering Gear is the equipment provided on ships to turn the ship to left (Port side) or to right (Starboard side) while in motion during sailing. The Steering Gear works only when the ship is in motion and, does not work when the ship is stationary. All the ships are to be provided with, an efficient main steering gear, an auxiliary steering gear and, except for very small ships, the main steering gear should be power operated.

Manually operated, mechanical Steering Gears were in use during sailing ship days. Sailors with strong body were required to operate the Steering Gears. Later on, after the onset of steam engines, mechanized gears were used. Modern ships use all very sophisticated Steering Gear systems which could fall in either of the categories

  • Fully hydraulic type
  • Electro-hydraulic type
  • Fully electric type

We also saw a general overview about these Steering Gears in a previous article. In this article we will proceed to know more about their constructional details and components. Before studying further, just take a close look at the sketch of the Steering Gear arrangement which shows the various parts and components of a dual type system i.e. electro-hydraulic type gear arrangement.

Steering Gear Arrangement

Working of the Steering Gear

When the ship is required to be turned on receiving an order (say by 10° to port) from the Master or, the Duty Officer, the helmsman turns the steering wheel towards port until the rudder has reached 10° to port as read on rudder indicator. The mechanism of the Steering Gear works as under;

Complete Steering Gear system consists of three main parts namely

  1. Telemotor
  2. Control Unit
  3. Power Unit.

A brief description about the construction and working of these components is as follows

Telemotor unit comprises of two parts namely, Transmitter and Receiver. The Transmitter is located on the navigation bridge in the form of a wheel, which transmits the given order to the Receiver located in the steering gear compartment, by turning the steering wheel. The Receiver conveys this order to the Control Unit, also located in the steering gear compartment, via linear motion.

The Telemotor is generally hydraulic type, electric type or, as is the case with modern steering systems, it could be electro-hydraulic type. In olden days, Telemotors were purely mechanical type consisting of linkages and chains with sprockets. As they were operated manually, they required very healthy sailors to operate them.

Control Unit is the link between the Telemotor and the Power Unit. I receives signal from the Telemotor and operates the Power Unit until it receives another signal, this time from the Rudder through the Hunting Gear, to stop the operation of Power Unit.

Power Unit can be any prime mover like steam engine, diesel engine or, an electric motor, directly coupled to the Rudder; it can be an electro-hydraulic unit or, an all- electric unit complete with the Telemotor.