Valve Operated Rotary Vane Steering Gear: Hydraulic System Breakdown
A valve-operated rotary vane steering gear utilizes hydraulics to translate control signals from a bridge system into rudder movement. Here’s a breakdown of the hydraulic system, focusing on the path from the directional control valve to the rotary vane unit:
Components:
- Directional Control Valve: This valve is located near the bridge control system and receives electrical or mechanical control signals. It acts as a “gatekeeper” for hydraulic fluid flow.
- Hydraulic Pump: This pump, typically driven by an electric motor or diesel engine, pressurizes the hydraulic fluid within the system.
- Reservoir: This tank stores the hydraulic fluid and maintains its proper level.
- Pipelines: High-pressure hoses or steel pipes connect the various components and carry the pressurized fluid.
Operation:
- Directional Control Valve Movement: When the helmsman on the bridge operates the steering wheel or controls, this action sends a signal (electrical or mechanical) to the directional control valve.
- Valve Port Movement: Based on the received signal, the directional control valve spool or poppet moves within the valve body. This movement opens specific ports within the valve, directing the flow of hydraulic fluid.
- High-Pressure Fluid Path: With the valve positioned correctly, high-pressure fluid from the pump is directed to one side of the rotary vane unit’s chamber.
- Low-Pressure Fluid Path: Simultaneously, the valve also opens a passage for the hydraulic fluid on the opposite side of the rotary vane unit to return to the reservoir. This creates a pressure differential across the unit.
- Rotary Vane Movement: The pressure difference within the rotary vane unit acts on a set of vanes housed within a cylindrical rotor. This pressure pushes the vanes, causing the rotor to rotate in a specific direction.
- Rudder Movement: The rotating shaft of the rotor is typically connected to the rudder stock through a reduction gear mechanism. This translates the rotary motion of the vane unit into the desired angular movement of the rudder.
Additional Considerations:
- Pressure Relief Valve (Optional): A pressure relief valve might be incorporated within the system to protect against excessive pressure buildup in case of malfunctions.
- Pilot-operated Valves: In some designs, pilot-operated directional control valves might be used. These valves utilize a smaller, separate hydraulic circuit to control the main valve spool, offering more precise control over fluid flow.
Overall, the valve-operated rotary vane steering gear utilizes a directional control valve to direct pressurized hydraulic fluid, creating a pressure differential within the rotary vane unit. This differential drives the rotation of the vanes, ultimately resulting in the desired movement of the rudder.