Vetus OB175 Instructions D'installation page 8

Introduction
A hydraulic steering system consists basically of one or more
pumps and a cylinder, see Diagrams '1' and '2' *.
The pump MTPxx10R is fitted with a non-return valve. This pre-
vents any feel of rudder pressure at the steering wheel.
The pump is also fitted with a pressure-relief valve.
With a hydraulic steering system with two pumps, the non-
return valve also ensures that one pump can take over from the
other automatically, as well as preventing the running of the
unused steering pump. See Diagrams '1' and '2' *.
In a hydraulic system with three pumps (2 manual pumps and
1 EHP) the non-return valves are essential for the reasons
above; see Diagrams '3' and '4' *.
The EHP type 'R' is already equipped with a built-in check valve.
Following the recommendations below will result in a longer life
and better performance of your hydraulic steering system.
• Only use the type of hydraulic oil as specified in the Technical
Data.
• Carry out regular maintenance.
*) See 'Hydraulic Diagrams' on page 32-33 for the various con-
nection diagrams.
Fitting
During assembly, avoid any welding or paint splashes or dam-
age to the steering pump spindle and the piston rod. These
could damage the oil-control rings causing oil leaks.
Steering pump
The filler cap should always be at the top, at the highest point.
When there is more than one steering pump in the installation,
all oil reservoirs should be connected together with a balance
pipe.
In order to ensure the
correct operation of the
oil suction valves in the
pump, the pump should
be mounted tilted back at
an angle of less than 20
degrees.
If this is not possible, the
oil suction valves must
be fitted with a spring. Consult VETUS for details.
With double operation, check that the lowest steering pump is
fitted with a filler cap without a hole.
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Cylinder
In order to ensure proper bleeding, the air-bleed nipples should
point upwards.
Provisions should be taken to protect the piston rod against
damp, dirt and sea water.
The tilt tube (2) has already been fitted.
Grease the brass nut (1) supplied separately.
Screw the brass nut (1) supplied separately onto one side of the
tilt tube (2).
Push the rod (3) through the tilt tube (2). Fill up the space
between the tilt tube (2) and the 2 brackets (4) using the spac-
er rings (5) supplied.
Finally, tighten the brass nut (1) and screw the brass nut lock
screw to the tilt tube (2).
Grease the moving parts of the S-link (7).
5 2
3
4
6
Note!
Tighten the self-locking nuts (6) in such a way that the complete
cylinder can still pivot on the tilt tube (2) while eliminating exces-
sive clearance.
Check free movement of the piston rod.
Hydraulic Steering Systems OB175, OB300
1 5
4
6
7