A Pocket Guide to Steering Gear System on Ships

A rudder, which helps in turning a ship as and when required. Rudders are the principal system for the entire motion and control of the ships. But we mustn’t forget that the entire rudder action is dependent on another pivotal system called the Steering Gear.
Steering gear integrated with the rudder system defines the complete ‘turning mechanism’ mandatory for each and every ship, irrespective of size, type, and operation.
In this book, we become familiar with
- Basic Operation and Types
- Rules and Regulations Requirement
- Testing Steering Gear
- Alarms and Checks
- Emergency Steering

1. Operation, Procedures and Safeties
A Pocket Guide to
Steering Gear
System on Ships
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2. Marine Insight©

“A Pocket Guide to Steering Gear On Ships”

Publication date: Sep’2018

Editor : Raunek Kantharia

Published by: Marine Insight
www.marineinsight.com

Graphic Design: Anish Wankhede
Copyright 2018 Marine Insight

NOTICE OF RIGHTS

All rights reserved. No part of this book may be
rewritten, reproduced, stored in a retrieval system,
transmitted or distributed in any form or means,
without prior written permission of the publisher.

NOTICE OF LIABILITY

The authors and editors have made every effort
possible to ensure the accuracy of the information
provided in the book. Neither the authors and Marine
Insight, nor editors or distributors, will be held liable
for any damages caused either directly or indirectly by
the instructions contained in this book, or the
equipment, tools, or methods described herein.

3. Content
3 Title of the book
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2









3



4




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Basic Operation and Types

•Hydraulic / Electro-Hydraulic
•Types of Pumps and Actuators
•Ram Type
•Rotary Vane Type



•Regulatory Requirement
•Safematic Operation
•Other Important Requirement

Basic Requirements


Testing Steering Gear

•Tests
•Drills
•Checks
Alarms and Checks •Steering Gear Hydraulic Lock
•Motor Overload
•Power and Phase Failure
•Hydraulic Oil
Emergency Steering

•Requirement
•Procedure

4. 4
Steering Gear integrated with the rudder system defines the
complete ‘turning mechanism’, which is mandatory for each and every
ship irrespective of size, type and operation.

Steering gears have been an indispensable part of the ship’s machinery
since the advent of the ships which were operated by hand. As ships
continued to grow in size and became faster, modern systems easing
human effort were incorporated.

Basically, there are two types of commonly used steering gear systems
at present:

•Hydraulic

•Electro-hydraulic type

A Pocket Guide to Steering Gear On Ships

5. 5
The main control of the steering operations is at the helm of any
ship, similar to an automobile where the entire control of the
vehicle’s “steer-ability” rests on the steering wheel of the driver. The
‘control force’ for turning is triggered off from the wheel at the helm
and passed on to the steering gear system.



















The steering gear system generates a torsional force at a certain
scale which is then is transmitted to the rudder stock that turns the
rudder. The intermediate steering systems of a modern day ship can
be multifarious with each small component having its own unique
function.

In hydraulic and electro-hydraulic systems, hydraulic pressure is
developed by hydraulic pumps which are mainly driven by electric
motors (electro-hydraulic systems) or sometimes through purely
mechanical means (hydraulic systems).
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A Pocket Guide to Steering Gear On Ships

6. 6
However, advanced electro-hydraulic systems are mainly
predominant in ships nowadays.

These hydraulic pumps play a crucial role in generating the required
pressure to create motions in the steering gear and trigger the
necessary rotary moments in the rudder system.

These pumps are basically of two major types:

1.Radial piston type (Hele-Shaw)

2.Axial Piston type () Swash plate

Actuators mediate the coordination between the generated
hydraulic pressure from pumps (driven electrically, of course) and
the rudder stock by converting the pressure into a mechanical force,
creating a turning moment for the rudder.

Actuators are now mainly electrically driven by power units.

These actuators, in turn, can be of two types:

•Piston or cylindrical arrangement

•Vane type rotor

The types of actuator systems depict the types of steering gears
system, which are also segregated as Ram type and Rotary Vane
type arrangements. Let’s discuss them in brief.


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A Pocket Guide to Steering Gear On Ships

7. RAM TYPE STEERING GEAR

Ram type steering gear is one of the commonly used
steering gear systems and is quite expensive in construction.
The basic principle is same as that of a hydraulically-driven
motor engine or lift. There are four hydraulic cylinders
attached to the two arms of the actuator disc, on both sides.

















These cylinders are directly coupled to electrically driven
hydraulic pumps, which generate hydraulic pressure through
pipes. This hydraulic pressure present in the pumps imparts
motion to the hydraulic cylinders, which in turn corresponds
with the actuator to act upon the rudder stock.

As we know, rudder stock is an indispensable part of the
entire steering gear arrangement of ships and dictates the
exact behavior of the rudder response.
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A Pocket Guide to Steering Gear On Ships

8. The sense of turning the rudder is guided by the action of the
hydraulic pump. The physics behind its function can be
explained better with the help of the following figure.



















Here the cylinders denoted A and C are connected to the
discharge side of the pump. This generates a positive
pressure in the piston cylinders. On the contrary, the other
two cylinders B and D are connected to the suction side of
the pump.

This creates a negative pressure in the cylinders. The
resultant forces create a clockwise moment in the rudder. To
put it simply, positive and negative pressures from pumps
generate lateral forces on the rams which act in couples for
turning the rudder stock.

Similarly, to put the rudder stock in anticlockwise direction,
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A Pocket Guide to Steering Gear On Ships

9. the reverse is carried out, viz. the discharge ends of the
pumps are connected to the cylinders B and D, while the
suction side of the pumps are to A and C. This reverse
pressure flow from hydraulic pumps is achieved with the help
of control valves operated from the wheelhouse.

The ram type steering gear arrangement produces a
considerably high value of torque for a given applied power.
The hydraulic oil pressure varies from 100 bars to 175 bars
depending on the size of the rudder and torque required.

Basic Functioning of 4 Ram Steering Gear

The bridge wheel is moved to alter course (say to port),
which causes the telemotor transmitter to send a signal
corresponding to the degree of helm to the telemotor
receiver in the steering gear.

The receiver in response moves the receiver rod, which
cause floating link to move and thus put the hydraulic pump
on stroke. Hydraulic oil is pumped into one cylinder, while the
pump is taking suction from other cylinder, thus forcing the
ram to move, which through the tiller moves the rudder
stock. As the rudder stock moves, a part of the hunting gear
rod also moves, causing the floating link to move.

When the rudder takes desired position as given from the
bridge, floating link puts the hydraulic pump off stroke. The
rudder will remain in this position until further signals are
received from the tele-motor transmitter. The pipe
arrangement of the four-ram system in the following figure
shows the connection from two pumps and four rams.
Because of non-reversing lock arrangement, one pump can
be stopped with the valve left open.



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A Pocket Guide to Steering Gear On Ships

10. All four rams work together in normal operation with single
pump. In case of damage, either pair of rams can be isolated
from the pump and allowed to become idle with the bypass
valve open. The other pair of ram then operates as a two-
ram gear system.

The rudder can be locked by closing the shutoff valve on the
rams in case of emergency. The relief valves are installed in
the system to avoid pressure rise of 10% above normal and
also to connect the opposing rams for avoiding pressure
damage.

Each pump has suction connection through non-return valve
from the oil replenishing tank.
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A Pocket Guide to Steering Gear On Ships

11. ROTARY VANE TYPE STEERING GEAR

In rotary vane steering gear, there is a fixed housing in which
two vanes rotate. The housing along with the vanes form
four chambers. The physics behind its operation is similar to
that of ram type with a small difference.





















When chambers A and C are pressurised, there is an
anticlockwise rotation of the vanes. A and C are connected
to the discharge side of the pump while chambers B and D
are connected to the suction side of the pump.

Similarly, when clockwise rotation is required, B and D are
connected to the discharge side of the pump while A and C











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A Pocket Guide to Steering Gear On Ships

12. are connected to the suction side of the pump. The rotary vane
system is also operated by specialized control valves and the
differential pressurization of the chambers cause rotational
moments in the vane. Rotary vane type arrangement is used when
the pressure requirement is 60 to 100 bar for producing required
torque.

The main advantage of rotary vane type steering gear is that it
requires less hydraulic pressure and power for producing the same
amount of torque as ram type.


















There are 3 fixed and 3 moving vanes, which can make rudder
angles up to 70 degrees, i.e 35 degrees on each side. This
arrangement has several other advantages such as lower
installation cost, less weight and smaller space required. The fixed
and rotating vanes are of spheroidal graphite cast iron. Keys are
often provided in the rotary vanes for proper strength and
orientation.


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Image Credit: Chris Allen/ Wikimedia
A Pocket Guide to Steering Gear On Ships

13. 13
The performance of steering gear depends on some main aspects.
These basic requirements to be invariably met by all steering gears are
guided by rules set by classification societies.

They can be briefly outlined as:

•Capability: As per standard requirements, the steering gear should be
capable of steering the ship from 35 degrees port to 35 degrees
starboard and vice-versa with the vessel plying forwards at a steady
head-on speed for maximum continuous rated shaft RPM. and
summer load waterline within a time frame of maximum 28 seconds

•Fail Safe: The major power units and the control systems are to be
duplicated so that if one of them fails, the other can easily substitute
for them as standby


Image Credit: Thomas Farr
A Pocket Guide to Steering Gear On Ships

14. •During one unit inoperable: With one of the power units
inoperative, the rudder shall be capable of turning 15 degrees
port to 15 degrees starboard (and vice-versa) within a time
frame of 1 minute with the vessel moving at half its rated
maximum speed or 7 knots (whichever is greater) at summer
load line

•Emergency Power Supply: The steering gear system is to be
provided with additional power unit (hydraulic pump etc.)
connected to the emergency power supply from Emergency
Generator, which shall be capable of turning the rudder from
15 degrees from one side to other side within 60 seconds with
the vessel moving at a maximum service speed or 7 knots,
whichever is greater

•Single Failure Criteria: The basic rule states that a steering
gear should be capable of recovering from a single hydraulic
failure within 45 sec. After a failure, a minimum of 50%
capability of the steering gear would be available. If the
steering gear satisfying single failure criteria, and after a single
failure 5% capability of the steering gear is available, this is
called 2.50% torque unit single failure

•100% Redundancy: This implies either two complete and
independent hydraulic steering gears or two interconnected
circuit with automatic isolation of one unit from other should
there be a loss of hyd. fluid. This is called 100% redundancy
system





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What is Follow-up Steering Gear?

It is a closed loop control system. In this
system when helmsman gives order (say 10
0
port) on steering wheel, rudder will be on 10
0
P till the new movement is given. No need to
hold the wheel on said position.

What is Non-Follow-up Steering Gear?

It is an open loop system. In this system when
helmsman gives order( say 10
0
port) on
steering wheel, rudder will turn on 10
0
p.
Helmsman will hold the wheel in this position
only to keep the rudder in said position.
A Pocket Guide to Steering Gear On Ships

15. Safematic Steering Gear System

As the name suggests, the Safematic system is a safety
setup to ensure the steering gear is operational even if one
section of it experiences an oil leakage due to pipe burst or
other defects.

This system also allows to carry out emergency work on an
isolated section of the gear while the rest of it is operational.

It comprises of a Safematic control box which senses (the oil
level), controls (the pump operation), and isolates (using
safematic valve) the damaged section of the steering gear.

























































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A Pocket Guide to Steering Gear On Ships

16. This system helps to restore the ship’s manoeuvrability
immediately, and loss of hydraulic fluid is kept to a minimum,
due to the short time required for automatically detecting,
isolating and switching over.

Safematic Operation

Refer the previous diagram and assume that the bottom
pump is operational and supplies power(hydraulic) directly to
cylinder group 2 and through the SAFEMATIC control valve
block to cylinder group 1 [ ports A to D and ports C to B].

If there is a leak in cylinder group 2, i.e. the lower pump or
any of its associated pipes, the oil level in the tank (for that
group) will diminish and activate a low-level float switch,
which in turn, will enable the left side solenoid on the
SAFEMATIC block.

This will result in changing of the connectivity of the ports –
A and B will be connected to allow passage of oil from one
cylinder to another cylinder, i.e. group 1.

The ports C and D will be blocked, thus isolating the
defective part of the system, i.e. the lower pump, cylinder
group 2 and the associated pipelines.

While the Safematic valve is isolating the defective section,
the Safematic control will start the other (upper) pump
automatically to resume the steering gear operation.

























































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A Pocket Guide to Steering Gear On Ships

17. Other Requirements Related to Steering Gear

• A block diagram displaying the steering system, the
changeover procedure from remote to local steering and
steering gear power unit indicating the emergency supply
unit must be clearly mentioned


























•
This diagram must be pasted in Navigation Bridge and
steering gear compartment





























































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A Pocket Guide to Steering Gear On Ships

18. •All officers and crew concerned with the operation and
maintenance of steering gear system must be familiar
with changeover procedure from one system to other

•Emergency steering drills to be carried out in less than
three months period

•Date and time for the tests, checks and drills carried out
in steering gear system must be recorded

•To prevent motoring of standby pump due to hydraulic
pressure exerted by the running pump, a centrifugal
coupling, consisting of ratchets and pawls, is provided
between motor and pump. The pawls moves free when
the concerned motor is running but will lock the rotation in
the opposite direction when motor is stopped


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A Pocket Guide to Steering Gear On Ships

19. •To maintain a standard practice for all steering gear
operation, time taken to move rudder from 35
0
on one
side to 30
0
on other side shouldn’t be more than 28
seconds

•If the rudder movement is faster than 28 sec, then to
avoid undue bending stresses and vibration on the ship
hull and machinery, the last 5
0
movement is kept very
slow


Requirement for Lube Oil Usage in Steering Gear:

-The lube oil used in the steering gear system should not
react with water, salt and O2

-It should not emulsify during condensation in reservoir

-Should have low pour point

-Should have high flash point

-Must have low viscosity to reduce the frictional drag

-Should not have sludge forming characteristics

-Should be non-corrosive to the steering gear pipes and
parts.
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A Pocket Guide to Steering Gear On Ships

20. 20
Safety of the ship is the prime concern for seafarers onboard and
for governing authorities. There have been many ship accidents in the
past due to the failure of steering gear.

Hence, crew must be careful in maintaining and testing all the aspects of
steering gear present onboard.

Specifications and guidelines are laid down by the authorities and in the
safety management system or SMS of the ship to continuously monitor
the operation and safety system of the steering gear to avoid any
accident due to its failure.

The guidelines for tests and drills are provided in chapter V regulation 26
of SOLAS 74.
Testing Steering
Gears on Ship
A Pocket Guide to Steering Gear On Ships

21. Following tests and drills to be carried out within given period of
time as stated in chapter V-

Testing and Drills - Within twelve hours before departure of the
ship from port, following systems to be checked and tested:

•Main steering gear and system

•Auxiliary steering gear and system

•The remote control systems of steering gear

•The steering position indicator on the navigation bridge





















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A Pocket Guide to Steering Gear On Ships

22. •The rudder angle indicators showing actual position of the
rudder

•The emergency power supply to one of the steering unit

•Power failure alarms for the remote steering gear control
system

•Automatic isolating arrangements and other automatic
equipment

•Power unit failure alarms for the steering gear unit

Following listed procedure must be included along with the
checks and tests described above:

1.The full movement of the rudder as per the required
capabilities of the steering gear system present onboard

2.A visual inspection of all the linkages and connection in the
steering gear

3.The means of communication between the steering gear room
and navigational bridge must always be operational

4.Check the lube oil tank level and test for contamination

5.Check the solenoid, bypass, shock relief, etc. for their correct
functioning

6.Check hunting gear linkages

7.Check the oil filters in the hydraulic system

8.
Oil pressure check. If erratic, it means air in the system









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A Pocket Guide to Steering Gear On Ships

23. 23
It is very important to continuously monitor the performance of the
steering gear operation. Another important aspect is to regularly check
the alarms provided in the steering gear safety system.

This is to ensure that the alarm indication of the steering system is
working fine as if the alarm is not sounded during emergency, the crew
will not be made aware of the problem as the steering gear room is
hardly manned.

The steering gear motor, oil level in the steering gear, steering lock etc.
are some important types of alarm provided in the system. There are no
shutdown functionality provided in the steering gear system as it is
essential to keep the steering gear running when maneuvering the ship
in congested water or channel even in case of steering machinery
emergency.

A Pocket Guide to Steering Gear On Ships

24. Steering gear Hydraulic Lock Alarm:

Hydraulic lock alarm is activated when-

•Position of the variable displacement pump control system
does not corresponds to the given order, or

•Incorrect position of the 3-way full flow valve is detected in the
constant delivery pump system

Testing Hydraulic Lock Alarm -

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A Pocket Guide to Steering Gear On Ships

25. Steering Gear Overload Alarm:

Whenever hydraulic motor or heleshaw pump motor draws
excessive current due to technical or machinery problem, or due
to bad weather, it gives an overload alarm. Continued
reoccurrence of this alarm could mean that the electrical motor
might burn.

Testing Overload Alarm -




















Power Failure and Phase Failure

An audible and a visible alarm must activate in the pilot house
upon

•Failure of power to the power unit of any steering gear


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A Pocket Guide to Steering Gear On Ships

26. •Failure of the electric power to the control system of any
steering gear

•Failure of any phase of a three-phase power supply

Testing Power and Phase Failure Alarm -






















Steering Gear Oil:

The hydraulic oil tank is provided with level and temperature
sensors. The lube oil filter is provided with the flow sensor to
check the condition of filter element.. Manually actuate the oil tank
level, temperature and filter sensor switch and ensure that the
appropriate alarm sounds in the ECR and in the Wheelhouse
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A Pocket Guide to Steering Gear On Ships

27. Testing Oil Related Alarm -





















Required characteristics for steering gear hydraulic oil: -

•L.O system must meet the load requirement

•No chemical reaction with water, salt, O
2 etc.

•Should not emulsify with condensation in reservoir

•Low power point, High flash point, Non-corrosive

•Low viscosity to reduce friction drag

•Non-sludge forming,














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A Pocket Guide to Steering Gear On Ships

28. 28
An emergency steering system, as the name suggests, is used
during the failure of the main steering system of the ship.

A ship consists of electromechanical steering gear unit which steers the
vessel from one port to other. Normally steering gear unit is a 2 or 4 ram
electro-hydraulically operated unit with two or more hydraulic motors for
the ram movement.

A situation can occur in which the remote control operation may fail and
there can be a sudden loss of steering control from the bridge. This can
be due to sudden power failure or electrical fault in the control system,
which leads to faulty tele-motor or servo motor that are used for
transferring the signal from bridge to the steering unit.

A Pocket Guide to Steering Gear On Ships

29. To control the steering of the ship at such emergency situation
with manual measure from within the steering gear room, an
emergency steering system is used.

Procedure for Emergency steering Operation

The following points should be notedfor emergency steering
operation:

•The procedure and diagram for operating emergency steering
should be displayed in steering gear room and bridge

•A hydraulic motor is given power supply from the emergency
generator directly through emergency switch board (SOLAS
regulation).


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A Pocket Guide to Steering Gear On Ships

30. •The motor to which the emergency supply is provided
should be displayed in the steering room.

•Ensure a clear communication for emergency operation
via VHF or ship’s telephone system.

•Normally, a switch is provided in the power supply panel
of steering gear for tele-motor; switch off the supply from
the panel.

•Change the mode of operation to manual and then select
the switch for the motor which is supplied with emergency
power.















A helms wheel or operating levers are provided to control the flow
of oil to the rams with a rudder angle indicator by operating the
appropriate solenoid valve. A safety pin is provided at the
manually operated helms wheel/lever to ensure that during
normal operations, the manual operation always remain in cut-off
mode. Remove that pin. For wheel arrangement, it can be turned
clockwise or anti clockwise for going port or starboard.
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A Pocket Guide to Steering Gear On Ships

31. For lever arrangement, two levers are provided to operate the
desired hydraulic ram after pressing and operating the solenoid
switch.






















If there is a power failure, through sound-powered telephone receive
orders from the bridge for the rudder angle. As soon as you get the
orders, turn the wheel and check the rudder angle indicator.

A routine check should always be carried out for proper working of
manual emergency system and steering gear system. An
emergency steering drill should be carried out every month
(prescribed duration – 3 months) in the steering gear room with
proper communication with bridge to train the ship’s staff for
emergency.
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