A hydraulically driven transverse thruster utilizes pressurized hydraulic fluid to generate a lateral thrust force, aiding in vessel maneuvering. Here’s a breakdown of its operation:
Components:
- Electric Motor: This motor, typically located below deck, drives the hydraulic pump.
- Hydraulic Pump: Converts electrical energy from the motor into pressurized hydraulic fluid.
- Reservoir: Stores the hydraulic fluid and maintains its proper level.
- Pipelines: High-pressure hoses or steel pipes carry the pressurized fluid to and from the thruster unit.
- Directional Control Valve: Located near the bridge control system, this valve receives electrical or mechanical signals from the operator and directs the flow of hydraulic fluid.
- Transverse Thruster Unit: This underwater unit houses the propeller and the hydraulic motor that drives it.
Operation:
- Command Signal: The helmsman on the bridge operates the controls (joystick, buttons) to activate the thruster. This sends a signal (electrical or mechanical) to the directional control valve.
- Valve Movement: Based on the received signal, the spool or poppet within the directional control valve moves, opening specific ports to direct the flow of hydraulic fluid.
- Hydraulic Fluid Flow: The valve directs pressurized fluid from the pump to one side of the hydraulic motor within the thruster unit. Simultaneously, it opens a passage for the fluid on the opposite side of the motor to return to the reservoir. This creates a pressure differential across the motor.
- Hydraulic Motor Rotation: The pressure difference acts on the internal components of the hydraulic motor, causing it to rotate in a specific direction. This rotation is typically clockwise or counter-clockwise depending on the desired thruster direction.
- Propeller Rotation: The shaft of the hydraulic motor is directly connected to the propeller within the thruster unit. As the motor rotates, it drives the propeller to spin in the same direction.
- Lateral Thrust Generation: The spinning propeller pushes water perpendicular to the vessel’s direction of travel, creating a lateral thrust force. Depending on the propeller rotation direction (clockwise or counter-clockwise), the thrust will push the vessel’s stern to port or starboard, aiding in maneuvering during docking, station keeping, or low-speed maneuvering situations.
- Stopping the Thruster: When the helmsman centers the control or selects “stop,” the directional control valve moves to a neutral position, blocking the flow of fluid to the hydraulic motor. This brings the thruster to a halt.
Additional Considerations:
- Pressure Relief Valve (Optional): A pressure relief valve might be incorporated within the system to protect against excessive pressure buildup due to malfunctions.
- Flow Control Valve (Optional): In some designs, a flow control valve may be used to regulate the flow of hydraulic fluid and adjust the thruster’s power output.
Overall, a hydraulically driven transverse thruster offers a reliable and efficient way for precise maneuvering by converting electrical energy into a controllable lateral thrust force through the use of hydraulics and a dedicated propeller unit.