Vetus MTP89 Instructions D'installation page 9

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 automatically take over from the other and also pre-
vents 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
diagrams, Page 41.
8
2.0108
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 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.
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
vertical.
If this is not possible, the pump suction valves will have to be fit-
ted 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.
Cylinder
The cylinder air bleed nipples should point upward to ensure
effective bleeding.
Rudder stops
Rudder stops
Rudder limit stops must be fitted to prevent overstressing 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.
Hydraulic Steerings 230 - 1200 kgm