Exam Question
(a) Sketch and describe a 'four ram electro hydraulic steering system', showing pump isolating valves, relief valves and bypass valves. (10)
(b) Indicate & explain valve position for one pump isolation and one unit isolation. (6)
Class 4 (4th Engineer)
MEKG
📅 Nov 2023
Reference Answer
### (a) Four-Ram Electro-Hydraulic Steering System
#### Principle of Operation
A four-ram electro-hydraulic steering system operates on the principle of converting electrical power into hydraulic power to produce the mechanical force required to turn a ship's rudder. The system consists of four hydraulic rams arranged in two opposing pairs, acting on a tiller arm connected to the rudder stock. Hydraulic pressure is provided by one or more electrically driven pumps, typically of the variable displacement type (e.g., Hele-Shaw or Swash Plate). The arrangement provides powerful and reliable rudder actuation and incorporates significant redundancy as required by SOLAS regulations.
The system utilizes the **Rapson Slide** principle, where the rams act on the tiller via swivel blocks sliding in grooves. This geometric arrangement ensures that the torque applied to the rudder stock increases as the rudder angle increases, providing maximum turning force when it is most needed.
#### Principle of Operation
A four-ram electro-hydraulic steering system operates on the principle of converting electrical power into hydraulic power to produce the mechanical force required to turn a ship's rudder. The system consists of four hydraulic rams arranged in two opposing pairs, acting on a tiller arm connected to the rudder stock. Hydraulic pressure is provided by one or more electrically driven pumps, typically of the variable displacement type (e.g., Hele-Shaw or Swash Plate). The arrangement provides powerful and reliable rudder actuation and incorporates significant redundancy as required by SOLAS regulations.
The system utilizes the **Rapson Slide** principle, where the rams act on the tiller via swivel blocks sliding in grooves. This geometric arrangement ensures that the torque applied to the rudder stock increases as the rudder angle increases, providing maximum turning force when it is most needed.
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