Aux 1 Unit 9 Q4

In a hydraulic steering gear system, the hunting gear serves as a critical feedback mechanism that ensures the rudder accurately follows the helmsman’s commands and maintains the desired position. Its primary purpose is to prevent overshoot and oscillation of the rudder, ensuring smooth and stable steering.

How it Works:

The hunting gear is essentially a mechanical linkage connected to both the rudder stock and the hydraulic control system. As the rudder moves in response to the helmsman’s commands, the hunting gear senses this movement and provides feedback to the control system. This feedback signal is used to adjust the hydraulic flow to the steering rams, gradually reducing it as the rudder approaches the desired angle. This prevents the rudder from overshooting the commanded position and then oscillating back and forth, a phenomenon known as “hunting.”

Key Benefits:

• Accurate Steering: The hunting gear ensures that the rudder accurately follows the helmsman’s commands, even in challenging sea conditions or during maneuvers.
• Stability: It prevents rudder oscillations or “hunting,” which can lead to instability and difficulty in controlling the vessel’s course.
• Smooth Operation: The gradual reduction of hydraulic flow as the rudder approaches the desired angle results in smoother and more controlled steering movements.
• Reduced Wear and Tear: By preventing overshoot and oscillation, the hunting gear reduces stress on the steering gear components, contributing to their longevity and reliability.

Components of a Typical Hunting Gear:

• Hunting Lever: Attached to the rudder stock, it senses the rudder’s movement.
• Floating Lever: Connected to both the hunting lever and the telemotor receiver (which receives steering commands from the bridge).
• Control Rod: Links the floating lever to the hydraulic pump control lever, adjusting the pump’s output flow based on the rudder’s position.

Operational Sequence:

1. Steering Command: The helmsman turns the steering wheel or moves the joystick, sending a command to the telemotor receiver.
2. Telemotor Action: The telemotor receiver moves the floating lever, which in turn moves the control rod.
3. Pump Control: The control rod adjusts the pump control lever, increasing or decreasing the hydraulic flow to the steering rams.
4. Rudder Movement: The rams move, turning the rudder in the desired direction.
5. Hunting Lever Feedback: As the rudder moves, the hunting lever also moves, pushing the floating lever back towards its neutral position.
6. Flow Reduction: This movement of the floating lever gradually reduces the pump’s output flow, ensuring the rudder stops at the commanded angle without overshoot or oscillation.

In Summary

The hunting gear in a hydraulic steering gear system is a vital feedback mechanism that ensures accurate and stable steering by preventing overshoot and oscillation of the rudder. It contributes to the overall safety, maneuverability, and efficiency of the vessel.

Let’s break down the action of the hunting gear in a hydraulic steering system:

Core Principle:

The hunting gear acts as a feedback mechanism, ensuring the rudder accurately follows the helmsman’s commands and maintains the desired position, preventing overshoot and oscillation.

Components:

1. Hunting Lever:
   • Attached to the rudder stock, it senses the actual movement of the rudder.
2. Floating Lever:
   • Connected to both the hunting lever and the telemotor receiver (which receives steering commands from the bridge).
   • Pivots around a central point.
3. Control Rod:
   • Links the floating lever to the hydraulic pump control lever (or spool), which regulates the flow of hydraulic fluid to the steering rams.

Operational Sequence:

1. Helmsman’s Command: The helmsman turns the steering wheel or moves the joystick, sending a signal to the telemotor receiver.
2. Telemotor Action:
   • The telemotor receiver moves, displacing one end of the floating lever.
3. Pump Control:
   • The movement of the floating lever, via the control rod, shifts the pump control lever/spool.
   • This action increases or decreases the flow of hydraulic fluid to the steering rams.
4. Rudder Movement:
   • The pressurized fluid acts on the rams, moving the tiller and, consequently, the rudder in the commanded direction.
5. Hunting Lever Feedback:
   • As the rudder moves, the hunting lever also moves, pushing the opposite end of the floating lever back towards its neutral position.
   • This creates a counteracting force against the telemotor’s initial movement.
6. Flow Reduction & Stabilization:
   • The movement of the hunting lever gradually brings the pump control lever/spool back towards its neutral position, reducing the flow of hydraulic fluid to the rams.
   • This slowing down of the rams ensures that the rudder stops at the commanded angle without overshooting or oscillating.

Key Points:

• Feedback Loop: The hunting gear creates a feedback loop where the rudder’s actual movement influences the control signal sent to the hydraulic pump, ensuring accurate positioning.
• Prevents Overshoot: By gradually reducing the hydraulic flow as the rudder approaches the desired angle, the hunting gear prevents the rudder from moving too far and then oscillating back and forth.
• Maintains Stability: This eliminates “hunting” and ensures smooth, stable steering, even in rough seas or during maneuvers.
• Essential for Autopilot: The hunting gear is crucial for the proper functioning of autopilot systems, as it provides the necessary feedback to maintain the desired course accurately.

In essence: The hunting gear acts like a “brake” on the hydraulic system, preventing the rudder from over-responding to steering commands and ensuring it settles precisely at the desired angle. This leads to improved steering control, stability, and reduced wear and tear on the steering gear components.