HYDRAULIC CYLINDERS FOR INBOARD ENGINES
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page 7
of 23
Installation and Maintenance Manual
NOTICE
Dual engine installations require the use of a tie bar.
Dual station installations require the use of 2 helms with non-return valve.
UC 69-I, UC 116-I, UC 168-I, UC 215-I and UC 293-I cylinders must not be installed on race boats.
Cylinder UC 69-I can be installed on inboard engines up to 150 hp and only with single cylinder and single helm.
All
ULTRAFLEX
steering systems must not be installed on boats equipped with engines whose maximum
horsepower is higher than the horsepower rating approved by boat manufacturer.
1.2 Warnings for the product correct use
Do not modify the steering cylinder in any way to fit it to your application, otherwise the cylinder will no
longer operate in safety and it will endanger the boat and the occupants.
WARNING
WARNING
WARNING
DANGER
1 PRODUCT DESCRIPTION
1.1 Hydraulic steering system operation
All
UFLEX
hydraulic steering systems are designed in conformity with UNI-EN-ISO 10592 and A.B.Y.C. P21
regulations. All
UFLEX
steering systems can operate at temperatures between -18°C (0°F) and +77°C (+170°F).
All the components are made for the marine environment, using materials and working processes which
offer long life and safety under the most extreme conditions. A hydraulic steering system consists of a steering
pump, a cylinder tied to the rudder or to the outboard or sterndrive engine
and the connecting hoses (see picture). Under normal operating conditions,
a turn of the steering wheel will pump the oil, which flows in through the
hoses to the cylinder, according to the turn direction. With the consequent
cylinder movement the oil will flow to the pump through the hoses and at
the same time moves the engine or the helm which are connected to the
cylinder. The pumps equipped with a valve which prevents outgoing fluid
from returning along the same hose, allow the operation of the steering
systems with two or more steering stations. The cylinders are double acting
and may be balanced or unbalanced. In the unbalanced cylinders the two
chambers have different volumes and so they need a different number of
turns of the steering wheel and a different rotation effort. The balanced
cylinders have same number of steering wheel turns in order to move the
helm from the center to the end stroke in the two opposite directions. A
well balanced steering system needs a correct choice of the pump for the
cylinder.
UFLEX
produces different pump models, which have different
capacity (cm
3
of oil moved each steering wheel turn) and for each type of installation. While choosing the
pump it is important to consider the cylinder volume. The number of starboard and port turns is determined
by the ratio between the cylinder volume and the pump capacity.
Example
: if the pump has a capacity of 28 cm
3
[1,7cu.in.] and the cylinder has a volume of 120 cm
3
[7,3cu.in.],
the formula looks like this: 120/28=4,2. Accordingly, the steering wheel will turn 4,2 times before the
cylinder will completely turn from one side to the other. In case of installations with double cylinders
connected in parallel the cylinder volume must be added. Applications with less than 4 turns are not
recommended, as they need a higher effort, applications with more than 8 turns are also not recommended,
as the response of the boat to steer is slowly.
pump
l
l
hydraulic hose
l
cylinder
helm
l
The maximum system torque must be calculated by the user according to the type of application used, the
helm number and features, the boat speed, the type of boat,etc.
NOTICE
All inboard cylinders can use standard KIT OB only if used with
UFLEX
UP Series hydraulic pumps whose pressure
relief valve (max pressure) is set at 70bar (1000PSI) while they must use KIT OB SVS if used with SVS Series
pumps or Master Drive systems.
WARNING
