Norway’s MariNe iNdustries
New steering gear for larger vessels
A new design of four-vane type steering gear intended primarily
for applications on larger vessels, such as VLCCs and larger types of
containerships has been developed by Rolls-Royce.
R
olls-Royce says a prototype of for IMO compliant applications (the ‘The actuator in the IRV series has a
its latest four-vane steering gear IRV, IMO Rotary Vane), both being double sealing system, and a specially
will be completed early in 2008, versions of the well known ‘Frydenbö’ designed sensor system that maintains
after which it will undergo extensive rotary steering gear. The company constant control of the integrity of the
testing. notes that IMO regulations require seals’, the company says. ‘The control
The rotary steering gear will go head to compliance with the principle of ‘single system modulates the flow of oil to the
head with the ram-type of steering gear failure criteria’ for large tankers over actuator in order to give a soft start
produced by the company’s competitors, 100,000dwt, a requirement met by and low rudder speed for small rudder
which currently tend to dominate the the IRV series, which incorporates movements, and the oil flow gradually
market. Rolls-Royce highlights the fact automatic isolation of the actuator’s increases up to full flow, allowing full
that rotary vane steering gear is more dual hydraulic system. The actuator is turning speed on the rudder.
flexible than the ram-type, as well as equipped with a double sealing system,
being more compact. It also allows for completely separating the actuator in Precise postioning
greater rudder angles, and can thus two individual pressure chambers. In The system thus ensures very precise
enhance manoeuvrability and provide addition, the specially-designed sensor rudder positioning for small rudder
improved control at low speeds, such as system maintains constant control of the angles, with close course-keeping,
when docking. integrity of the seals. while the full flow provides for full
Another important advantage is that, manoeuvring requirements when
with fewer components, the new concept Polymer seals needed. In this way, the simple and
weighs 50% less than conventional ram- In the new steering gear, industrial- reliable fixed displacement screw pump
type steering gear, and is much easier standard screw spindle pumps and is efficiently controlled to provide
to install. Furthermore, almost all of electric motors are combined with smooth and accurate steering in line
the piping for the new steering gear is carefully selected polymer seals and with a variable displacement pump,
internal, with the exception of the piping the Frydenbö range’s proven modulated without introducing the complexity of
between the actuator and the power pack, flow control valve. such a pump.’ NA
so the risk of leakage is much reduced,
and the new design has no external
moving parts.
Sinopacific deal seals record year
Less vibration
The company also notes that the rotary
vane principle - which ensures constant rolls-royce has signed its largest contract with Chinese shipbuilder
torque throughout the steering sequence, Sinopacific, to provide steering gear and deck machinery worth US$42
providing maximum power output - million.
produces less vibration, and hence less Bjorn Johnsen, Rolls-Royce vice president sales and marketing (Greater
noise, than some of the alternatives. China) – marine, said: ‘This order takes us to a record in China this year,
Rotary vane steering gear usually uses with contracts for more than 700 ship sets of steering gear and to 300 ship
two or three vanes. Three-vane steering sets of deck machinery. The Chinese market is now the biggest global
gear has the advantage of providing market for Rolls-Royce for commercial merchant ships.’
more torque than two vanes, but it also John Jin, Sinopacific director and vice-president, said: ‘This extensive
limits rudder angle. In the new, four-vane contract is a result of Sinopacific’s wish to work with fewer and stronger
configuration, the rudder angle is limited companies able to offer quick and reliable service.’
to 35degs but, being a four-vane system, The contract covers 34,000dwt-118,000dwt bulk carriers and 16,500m
3
a high level of torque and a particularly capacity LPG vessels. The first equipment will be delivered in the first half
powerful steering gear results. of 2009.
There are two versions of the new rolls royce said its marine facility in shanghai was its largest investment
four-vane steering gear, for non-IMO in China to date. Equipment completed includes tunnel thrusters, rudders,
applications (the RV-6000-4) and control and steering systems, and deck machinery.
50
The Naval Architect January 2008
NA Jan - p50+
51.indd 50 08/01/2008 09:24:08
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