Maintaining Steering in an Electro-Hydraulic Steering Gear
Here’s how steering can be maintained in an electro-hydraulic steering gear system in case of failures:
(a) Telemotor System Failure:
Modern electro-hydraulic steering gear systems typically incorporate a backup steering method in case the telemotor system (electrical control system) fails. This backup can be:
- Local Control Station: A manual control station located near the steering gear allows the helmsman to directly control the hydraulic valves using levers or a joystick. This bypasses the telemotor system and provides direct mechanical control of the rams.
- Alternative Control System: Some systems might have a secondary electronic control system independent of the main telemotor. This redundancy allows for continued operation even if the primary control system fails.
- Emergency Steering Gear (Optional): In some vessels, a completely separate emergency steering gear system might be available. This system could be:
- Hydraulic (non-electro): Powered by a dedicated pump and reservoir, it uses manual controls to operate the valves.
- Non-hydraulic: A mechanical steering gear operated by a wheel or tiller, independent of the main hydraulic system.
(b) Total Hydraulic System Failure:
If there’s a complete failure of the hydraulic system, maintaining steering becomes very challenging. However, some options might be available depending on the vessel’s design:
- Emergency Steering Gear: As mentioned earlier, if an emergency steering gear system is present, it becomes the primary means of control.
- Rudder Bracing (Last Resort): In extreme situations, if no other steering option is available, the rudder might be physically braced in a near-amidships position using chains or cables. This would severely limit maneuverability but could provide some directional control in calm seas.
Important Considerations:
- Crew training is crucial for effectively utilizing backup steering methods in case of failure. Regular drills and familiarization with alternative control systems are essential.
- The effectiveness of backup steering methods (especially emergency gear) can be limited compared to the primary electro-hydraulic system.
- Maintenance plays a vital role. Regularly servicing the telemotor system, hydraulic components, and backup steering gear helps ensure their functionality when needed.
By incorporating redundant control systems and emergency options, electro-hydraulic steering gear systems aim to maintain some level of control even in case of failures, enhancing overall vessel safety and maneuverability.