Check Valves - Raymarine Hydraulic Pump Installation Manual

Hydraulic Pump - Installation Guide
• Try to keep hydraulic fluid loss to a minimum when installing the
pump. This will reduce the time and effort required to bleed the
system of trapped air after installation:
• non-pressurized systems: temporarily fit a non-venting plug
to the helm reservoir vent to minimize fluid loss
• pressurized systems:
WARNING:
Before disconnecting any pipes on pressurized systems, you
MUST release the pressure at the reservoir by following the
manufacturer's instructions.
• Follow the manufacturer's instructions if you fit any T-pieces.
• All hydraulic pipes should slope upwards towards the reservoir.
• A set of bleed valves near the steering ram, fitted at the highest
point, will allow any air to escape upwards.
CAUTION:
Do not use PTFE tape on hydraulic pipe connections. If necessary
use a pipe-sealing compound to ensure a leakproof joint.
CAUTION:
Before running the pump for the first time, make sure the system
contains sufficient hydraulic fluid. You will damage the pump if
you let it run when 'dry'.

Check valves

For single-steering position boats:
• Consult the steering gear manufacturer to determine whether the
helm pump is fitted with reversing check valves:
• without check valves, the autopilot pump will drive the helm
pump (sometimes referred to as 'motoring the wheel') instead
of moving the steering ram
• If the boat has a single helm pump system without check valves,
you must incorporate a double pilot check valve (part number
M81166) as shown in Figure 5.
• A double pilot check valve may also be necessary on long tubing
runs - otherwise tubing expansion may cause poor autopilot
performance. Install the check valve as shown in Figure 5.
Note: If the boat has two steering positions, it will already have check
valves installed so the two wheels can operate independently.
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