Vetus MTC30 Instructions D'installation page 9

Introduction
A hydraulic steering system basically consists of one or more
pumps and a cylinder. See diagram 'A' *.
When the steering system includes just one pump, a non-
return valve can be installed between the cylinder and the
pump. This prevents pressure on the rudder being felt at the
helm.
This non-return valve can be fitted separately or a pump with
built-in non-return valve can be fitted.
N.B. A pump with built-in non-return valve is also fitted with a
pressure release valve.
See diagrams 'B1' and 'B2' *
When a separate non-return valve is fitted, the unused connec-
tion, for a second pump, must be sealed off.
When a hydraulic steering system with 2 pumps is used, a non-
return valve must be fitted. This ensures that the one pump can
automatically take over from the other, and also prevents
unnecessary rotation of the unused steering pump. See dia-
grams 'C1', 'C2', 'D1' and 'D2'.
Either a separate dual non-return valve can be fitted or use two
pumps with built-in non-return valves.
For the reasons given above a hydraulic steering system with 3
pumps must also be fitted with non-return valves.
Examples are given in diagrams 'E1' and 'E2' of systems with
an Electro-Hydraulic Pump (EHP) (with non-return valve) and 2
manually operated pumps.
The Vetus EHP type 'R' is already equipped with a built-in non-
return valve.
Examples are given in diagrams 'F1' and 'F2' of systems with an
Electro-Hydraulic Pump (EHP) (without non-return valve) and 2
manually operated pumps.
The EHP (with reversible motor) is shown in diagrams 'F1' and
'F2' connected via a separate (dual) non-return valve. For the
manually operated pumps diagrams 'E1' and 'F1' show a sepa-
rate dual non-return valve and diagrams 'E2' and 'F2' show
pumps with built-in non-return valves.
A by-pass valve must be fitted when emergency steering with
a tiller is required.
With an open by-pass valve, the oil can flow easily from one
side of the piston to the other and the hydraulic system will not
interfere with the emergency (tiller) steering. See Diagram 'G'.
Following the recommendations below will ensure a longer life
and better performance for your hydraulic steering system.
• Only use one type of hydraulic oil, as specified in the
Technical Data
• Carry out maintenance regularly.
*) For the various connecting diagrams, see Hydraulic circuit
diagrams, Page 40, 41.
Hydraulic Steering Systems 30 - 175 kgm
Fitting
During assembly, prevent welding spatters, paint splashes and
damage to the steering pump shaft and piston rod.
Damage can destroy the oil seals and cause leaks.
Steering Pump
The filler cap and balance tube must always be on top of the
unit, at the highest point.
*) When more than one pump is fitted, all oil reservoirs must be
connected by balance tubes.
The steering pump
may be installed in any
position between hori-
zontal and vertical.
Fit the threaded rods supplied into the steering pump using
Loctite ® .
The steering pump is fitted with a filler plug without air hole as
standard.
Single station system (1 steering pump): a filler plug with air
hole should be fitted.
Dual station system (2 steering pumps): a filler plug with air
hole should be fitted in the upper steering pump.
A filler plug with air hole is supplied separately.
Cylinder
The cylinder air bleed nipples should point upward to ensure
effective bleeding.
A Max. stroke of cylinder
B Rudder limit stops
Positioning of rudder limits
Rudder limit stops must be fitted to prevent over stressing the
cylinder when the piston is at top dead centre.
Fix the base of the cylinder to a sufficiently sturdy foundation;
this must be strong enough to accommodate the force (push
and pull) of the rudder on the cylinder.
It is best to install the cylinder in a dry, well ventilated space. If
this is not possible, take measures to ensure that the cylinder
rod is protected from damp, dirt and sea water.
ENGLISH
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