Vetus MTC30 Manuel D'installation page 10

Dual Non-return Valve
If a separate dual non-return valve is fitted this must be as close to
the steering cylinder as possible; the pressurised tubing between
the non-return valve and the cylinder remains under pressure and
should be made as short as possible.
Mount the duai non-return valve on an absolutely flat surface.
Connections marked 'P' are
for the steering pump; con-
nections marked 'C' are for
the cylinder.
2.3 Oil Expansion Tank
A part of the hand steering pump serves as an oil expansion tank.
The expansion capacity required depends upon the amount of oil
in the whole steering system and the expected maximum and mini-
mum ambient temperatures.
If the capacity is insufficient, oil wlil escape out of the breather hole
in the top pump filler cap.
Therefore, install an extra oil expansion tank when:
- the steering system consists of hand two steering pumps and an
electro-hydraulic pump;
- the total length of the tubes system is very large;
- large temperature differences can be expected during operation;
- if you expect considerable movement during operation, it is rec-
ommended that an extra oil expansion tank be fitted.
Furthermore, an extra oil expansion tank simplifies filling the system
and checking the oil level.
Fit the oil expansion tank above the top steering pump.
Block the breather hole in the top steering pump filler cap.
Connect the oil expansion tank to the topmost steering pump con-
nector tube using a hose and hose pillar.
N.B. This part of the steering system is virtually pressure-free (the
pressure depends upon the height of the fluid column between ex-
pansion tank and steering pump).
The VETUS oil expansion tank has a breather, when another make of
tank is used, ensure that an air breather is fitted.
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2.4 Connections
Never use Teflon tape for sealing the screw connections; liquid seal-
ants must be used with great care, sealant in the hydraulic system
will create problems.
Steering Pump:
Tube connections to the cylinder are already fitted. When a balance
tube has to be fitted, the connectors (G 1/4) must be assembled with
aluminium or copper sealing washers.
Cylinder:
The tube connections to the steering pumps are already fitted; a liq-
uid sealant is used. When the connectors are refitted the old sealant
must be removed and new iiquid sealant applied carefully.
Non-return Valve:
Assemble the parts in
the non-return valve us-
ing copper or aluminium
sealing rings.
Hose and Tube Installation
The hydraulic steering components are connected with nylon tubes
(MTC30 only!), nylon hoses or copper or steel tubes for the other
models.
Hydraulic system with double controls, both pumps without built-
in non-return valve:
Connect the tubes from both pumps with the cylinder via the sepa-
rate dual non-return valve.
See diagrams 'C1' and 'D1' .
Always keep the connecting tubes as short as possible in order to
restrict the internal resistance.
Hydraulic system with double controls, both pumps with built-in
non-return valves:
Connect the tubes from both pumps with the cylinder via T-pieces.
See diagrams 'C2' and 'D2' .
Always keep the connecting tubes as short as possible since they are
under pressure and this restricts the internal resistance.
It is recommended that the horizontal tubes be fitted at an angle of
about 3 cm per metre / 3/8 in per ft (pump side higher than cylinder
side) to ensure satisfactory bleeding.
Install the tubes or hoses in such a way that the risk of external dam-
age and corrosion (for metal tubes) or the effects of chemicals and
high temperature (nylon hose or tube) is reduced to the minimum.
Hoses or tubes which pass through a partition must be protected
with bulkhead sleeves, or bulkhead connectors.
Bends must be completely free of kinks; a kink in the tubing restricts
the free flow of hydraulic oil.
Hydraulic Steering Systems 30 - 175 kgm