Simrad Hydraulic Linear Drive
16
20220109E
compared to the ones with separate check valves. It should be observed
however, that this version does not have the extra protection against
internal leakage (bypass) as the models with separate check valves.
4.2
Reversible Hydraulic Pump
The pump consists of valve block, reversible gear pump, pressure
operated check (non-return) valves, electric permanent magnet motor,
suction valves and slide.
The pump is reversible, i.e. the motor changes direction of rotation
and the gear pump delivers oil to that side of the rudder cylinder
dictated by the signal from the autopilot. When the motor is running,
the pressurised (or delivery) side will hold both check valves open,
using direct oil pressure upon the valve on the delivery side. This oil
pressure is also used to push a slide to open the valve on the suction
side.
When the motor stops, the spring in the check valve on the suction
side returns the slide to the neutral position. Both check valves are
now closed and the rudder cylinder locked. Both sides of the gear
pump are able to suck oil from the tank through the suction valves.
4.3
Hydraulic Rudder Cylinder
The rudder cylinder consists of the cylinder itself, actuator, actuator
rod, ball joint and base plate.
The actuator rod runs through the cylinder. The actuator area is
identical on both sides, and this balances the cylinder.
Figure 8 HLD Assembly drawing (N3-111832)
(Shown with Fracmo type motor)
