SYSTEM OPERATION – Steering Modes
Page 48 of 80
connected through a Digital Helm Manifold. The digital helm manifold
contains Bypass and Limits solenoid operated valves.
When the DSC is on and the system is in any steering mode other than
STANDBY/MANUAL the Bypass solenoid is energized. With this solenoid
energized hydraulic flow from the digital helm circulates through the
manifold which allows the digital helm to be turned without pumping
hydraulic fluid to the steering gear. When the Bypass solenoid is de-
energized either, automatically or deliberately, the digital helm will operate
the steering gear manually.
The Digital Helm Manifold’s Limit solenoid valve serves to provide feel on
the helm, when the rudder position commanded by the digital helm is at
hard over. When the rudder position commanded by the digital FFU
device corresponds to port or starboard hard over the DSC will turn on the
hard over limit solenoid which will stop the flow of hydraulic fluid through
the Digital Helm Manifold. Stopping the hydraulic flow will cause the helm
to stop turning giving the operator feedback that the command is at hard
over. As soon as the helm is turned slightly in the opposite direction the
Limit solenoid is released allowing the helm to turn freely in the other
direction.
See also: 2.3.5
Digital FFU Command Device
2.4.4
Digital Rudder Order Indicator
1.4.3
Digital Helm Manifold Solenoids
3.3.6 Autopilot
Upon selecting AUTOPILOT mode the AUTOPILOT indicator will begin to
flash. At the same time the Autopilot Request output contact will close
(see 1.4.4
). This contact can be used by the autopilot system to indicate
that control is requested or to automatically switch the autopilot system to
AUTO mode. The steering control system does not change steering
modes at this time and continues to operate using the last selected
steering mode.
After the autopilot receives the autopilot request signal and it is ready to
assume control of the rudder the autopilot system is to close an autopilot
acknowledge contact (see 1.3.5
) connected to the DSC. Only after the
request and acknowledge conditions are met will the steering system
change the mode of steering control to AUTOPILOT. At this time the
previous mode indicator will turn off and the AUTOPILOT indicator will
change from flashing to steady. The rudder position will then be controlled
by the autopilot system through either the Autopilot Solenoid Command
Signals (see 1.3.3
) or the Autopilot Analog Command Signals (see 1.3.4).
Doc No.: MAN01504, 20-02-06 DSC 100 & MCP 100 Manual
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