Vetus MT230 Instructions D'installation page 10

1 Introduction
A hydraulic steering system basically consists of one or more pumps
and a cylinder. See Diagram '1' . *
When the system includes just one pump, a (dual) non-return valve
can be installed between the cylinder and the pump. This prevents
pressure on the rudder being felt at the helm.
See Diagrams '5' , '6' , '7' and '8' .
The non-return valve connection for a second pump must be sealed
off.
With a hydraulic steering system with 2 pumps, a dual non-return
valve must be installed. This ensures that one steering pump can au-
tomatically take over from the other and also prevents the unused
pump from rotating along. See Diagrams '5' , '6' , '7' and '8' .
For the reasons above, a hydraulic steering system with 3 pumps
must be fitted with two dual non-return valves; see Diagrams '9' , '10' ,
'11' and '12' .
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 Diagrams '2' , '4' , '6' , '8' , '11' and
'12' .
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 dia-
grams, Page 41.
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2 Fitting
During assembly, prevent welding spatters, paint splashes and dam-
age to the steering pump shaft and piston rod.
Damage can destroy the oil seals and cause leaks.
2.1 Steering Pump
The filler cap must always be on top of the unit, at the highest point.
When more than one pump is fitted, all oil reservoirs must be con-
nected by balance tubes.
In order to ensure the proper operation of the oil pump suction
valves, do not tilt the pump by more than 20 degrees from the verti-
cal.
If this is not possible, the pump suction valves will have to be fitted
with a spring.
Please consult Vetus when this modification is required.
When two pumps are fitted, make sure that the lower steering head
is fitted with a filler cap without a breather hole.
2.2 Cylinder
The cylinder air bleed nipples should point upward to ensure effec-
tive bleeding.
Rudder stops
Rudder stops
Rudder limit stops must be fitted to prevent overstressing the cylin-
der when the piston is at top dead centre.
Hydraulic Steerings 230 - 1200 kgm