Raymarine Autohelm 6000 User manual

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Any reference to Raytheon or
RTN in this manual should be
interpreted as Raymarine.
The names Raytheon and RTN
are owned by the
Raytheon Company.

Autohelm 6000
Installation & Operating Handbook

AUTOHELM 6000
Autohelm 6000 is one of the first of a new
generation of microprocessor controlled
autopilots and is suitable for sailing and motor
vessels of between 13m and 20m LOA (&I’ - 60’).
Whilst the engineering behind the system is
complex, operation has been simplified to the
point where switching over to autopilot merely
involves touching a single button. Complicated
control knobs have given way to microprocessor
automation so that steering performance is
continuously optimised over the entire range of
sea and vessel trim conditions.
Autohelm 6000 is simple to install and prepare
for sea trials. However, sound installation is vital if
the system’s full performance potential and
reliability are to be achieved. The installation
notes should be followed carefully and in cases
where special advice may be needed, you are
encouraged to contact our Technical Sales
Department where expert assistance is always
available.

CONTENTS
1 .o
General description
1 .l
Control system
1 .l .l Course computer
1.1.2
Control units
1 .l .3
Fluxgate compass
1 .1 .4
Windvane
1 .l .5
Auxiliary alarm
1.1.6
Radio navigation interface
1.2
Drive systems
1.2.1
Rotary drive unit
1.2.2
Linear drive unit
1.2.3
Hydraulic drive unit
1.3
System summary
2.0 Installation
2.1 .l Course computer
2.1 .2 Control units
2.1.3 Fluxgate
compass
2.1.4 Windvane
2.1 .5
Auxiliary alarm
2.1 .6
Radio navigation interface
2.2 Drive system
2.2.1 Rotary drive unit
2.2.2
Linear drive unit
2.2.3
Hydraulic drive unit
2.3
Cabling and power supplies
2.3.1
Signal cabling
2.3.2
DC supply cable
i:P
El
3:2.2
3.2.3
3.2.4
3.25
3.2.6
3.3
3.3.1
3.3.2
3.3.3
3.3.4
Operation
Basic principles
Controls
Fixed control units
Hand held control unit
Windvane system
Operating mode indication
Off course alarm
Radio navigation interface
Functional test procedure
Setting up
FunctIonal test procedure
Compass deviation check
Mechanical test procedures
4.0
44::
55-33
52
6.0
7.0
8.0
9.0
10.0
11 .o
Sea trials 31
First sea trials
Rudder control adjustment 33:
Operating hints
33
Unsatisfactory steering performance 33
Pilot fails to disengage on 34
selecting Stand-by
Maintenance
35
Fault location procedure 36
Warranty 37
After sales service
38
Service centres 39
Overseas representatives
41

1 .O GENERAL DESCRIPTION
Autohelm 6000 is a modular automatic pilot
system that can be built up to match the
individual requirements of all types of sailing and
power vessels. The rudder drive system may be
selected from a range of rotary, linear and
hydraulic systems, and the control system can be
customised to suit the layout of the vessel and the
owners individual requirements. All control units
are watertight and may be externally mounted
when necessary.
The most comprehensive installation is
illustrated in (Fig. 1) and provides for up to three
control units, together with a fluxgate compass
and optional wind vane course sensors. Provision
is also made for the addition of a Loran ‘c’ or
Decca Radio Navigation Interface. The most
basic installation would consist only of a central
course computer, fluxgate compass, drive unit
and a single control unit.
YP
WINDVANE
FLUX GATE RADIO NAVIGATION
INDICATING
CONTROL
UNIT
NON-
INDICATING
CONTROL
UNIT
HAND
HELD
CONTROL
UNIT
Fig. 1
DRIVE UNxw

1 .I CONTROL SYSTEM
1 .I .l COURSE COMPUTER
411 mm 116.2”)
,- ._
_- -..- -
/ II
\ 1
The course computer houses the central micro I
s-
computer and the drive system power amplifier
which confines the complete electronic system to I
a single module. The course computer plugs into
CL
QD an 1:
a connector unit to which all of the control system
cc
peripheral modules are connected. The course
\
/ ‘I
computer is thus easily removable from the vessel
for servicing by unplugging from the connector
unit. The course computer is splash-proof only
and must be mounted in a dry and protected
pclsition. The course computer is supplied in
12v and 24v configuration.
1 :I .2 CONTROL UNITS
Non Indicating and Indicating control units are
av,ailable, both of which provide full control of the
autopilot. The indicating control unit has a back-lit
digital course display, which also indicates cross
track error when the autopilot is supervised by the
Radio Navigation Interface system. Both types of
control unit are designed for surface mounting,
and would normally be situated adjacent to the
steering position(s).
A t-ran&held control unit is also available to
permit full control of the autopilot and power
steering from any position on deck. The hand-
held control unit is fitted with a 6m (19’) wander
lead and plugs into a bulkhead mounted
waterproof socket.
All three types of control unit are fully
waterproof for permanent outside location when
necessary, and are connected to a common bus
wil:hin the course computer connector unit.
i
) / 1
I-.--
178mm 17.0”) !159mm W3”)
,
n
T---I
7 F------1
L, I, \\\\ \ \ \ ;
23mm 2&F-
(Y) (9’)
4
76mm (3.O”l
1 .I .3 FLUXGATE COMPASS
The ftuxgate compass has been specially
developed for marine autopilot application. It is
excited and read by the system’s central course
computer and therefore does not contain any
active electronic components. The fluxgate is
gilnbal mounted to permit pitch and roll
movements of up to f40”. The compass is
bulkhead mounted and connects directly to the
course computer connector unit.
92mm (3.6”)
t- --
90mm (3.5”)
82mm (3.2”l

1 .I .4 WINDVANE
The windvane is designed for permanent
attachment to the after rail where it can be sited in
clear wind. The windvane interconnecting cable
feeds through the deck via a waterproof gland
unit and connects directly to the course computer
connector unit.
1 .1.5 AUXILIARY ALARM
The autopilot is provided with an automatic off
course alarm system which sounds from all
control units and provides sufficient audible
warning under most conditions. In cases where a
high power alarm is necessary, an auxiliary alarm
can be fitted. The auxiliary alarm is connected to
the main connector unit via a two core cable.
85mm
(3.35”)
1 .I .6 RADIO NAVIGATION INTERFACE
The autopilot can can be interfaced to any
Decca or Loran ‘C’ system that is provided with
a suitable autopilot output. The radio navigation
interface unit receives cross track error
information from the Decca or Loran ‘C’ system
and computes course adjustments to enable
the autopilot to steer to a selected way point.
The radio navigation interface connects to the
common control unit bus within the course
computer connector unit. The unit is designed
for surface mounting and would normally be
situated in the navigation area adjacent to the
Loran or Decca receiver.
O-
0
0
cl
0
- --
9
I l0mm (4.3”)
n
1lOmm (4.3”)
Your main distributor or Nautech Technical
Sales Department will be able to advise you of
Radio Navigation Systems with suitable
autopilot output.

1.:2 DRIVE SYSTEMS
Mechanical steering systems may be driven by
either a rotary or linear drive unit. Some steering
systems are fitted with an autopilot drive shaft,
and in such cases the choice of a rotary drive
system is straightforward. In general, if a drive
shaft exists and lost motion does not exceed 2%
of total rudder movement, the rotary drive unit
becomes the most economic choice. In all other
cases the linear drive unit will provide the simplest
installation since it may be connected directly to a
tiller link on the rudder stock. Total independence
of the mechanical steering linkage also allows the
linear drive unit to be used to power steer the
vessel in the event of steering linkage failure, and
this is an important safety feature. In addition,
minimisation of working parts improves the overall
efficiency of the rudder drive system and reduces
lost motion to an absolute minimum.
All vessels with hydraulicsteering systems will
require a hydraulic drive unit.
1.2.1 ROTARY DRIVE UNIT
The output shaft is driven by a continuously rated
servo motor via an efficient reduction gearbox.
The gearbox is dry lubricated to permit operation
in any attitude. A fail safe friction clutch within the
gear train engages automatically when the
autopilot is switched to ‘Auto’ and will disengage
instantly even under extreme load when the
autopilot is switched to ‘Stand-by’. The motor is
controlled by the course computer which also
regulates peak armature current and eliminates
the need for end limit switches.
Supply voltage
Peak output torque
Maximum shaft speed
Power consumption (typical
average)
Overall depth ‘A’
Suilable for vessels up to
Type 1
Type 2
12 volts (24 volts optional) 12 volts (24 volts optional)
240lb.ir-r. (27Nm)
425lb.in. (48Nm)
18 rpm 28 rpm
1 Z-3 amps 4-7 amps
75in. (190mm)
8.1 in. (21 Omm)
45ft. LOA (14m) 60ft. LOA (18m)
2 HOLES: 12.5mm (0.5”) diameter

12.2 LINEAR DRIVE UNIT
The output ram of the linear drive unit is driven by
a declutchable recirculating ball leadscrew which
enables the drive unit to be permanently coupled
to the rudder stock via a simple crank or tiller arm.
The drive is automatically engaged by means of
an internal friction clutch when the autopilot is
switched to ‘Auto’ and will disengage instantly
even under heavy load when the autopilot is
switched to ‘Stand-by’. The motor is controlled by
the course computer which regulates peak
current and eliminates the need for end limit
switches.
Supply voltage
Peak thrust
Maximum stroke. speed
Maximum stroke
Overall length at
mid stroke ‘A’
Tiller arm length ‘8’
(f35” rudder)
Maximum rudder torque
Power consumption
(typical average)
Suitable for vessels up to
Type 1
Type 2
12 volts (24 volts optional) 12 volts (24 volts optional)
5501bs (225Kg) 750lb. (340Kg)
1.2inJsec. (30mm/sec.) 1.3irVsec
(33mm/sec)
12in(300mm)
275in. (700mm)
1 Oin. (260mm)
5000lb.in. (570Nm)
1.5-3 amps
45ft. LOA(14m)
16in (400mm)
33.5in. (850mm)
14in. (350mm)
10,500lb.in. (1200Nm)
2.75-6 amps
60ft. LOA (18m)
25mm (1 .o”) 207mm (8.15”)
1
I
I66mn
(2.6”J
i
51 mm 12.0”)
‘A
czi
79mm
(3.1”l
r
18mm (0.7”RAD.)

1.2.3 HYDRAULIC DRIVE UNIT
The hydraulic drive unit consists of a precision _
gIsar pump with integral valve block driven by a
continuously rated servo motor. A special
pi’essure balance valve corrects the effects of
h!/draulic slip and isolates the pump from the
steering circuit when the autopilot is not
energised. The pump drive motor is connected
directly to the course computer which also
regulates peak pump pressure and eliminates the
need for end stroke limit switches.
I
I
'A 117mm
(46")
Supply voltage
Regulated peak pressure
Flow control
Peak flow rate (unloaded)
Maximum ram capacity
Power consumption
(typical average)
O~~erall length ‘A’
Type 1
12 volts (24 volts optional)
450lb.in’ (30bar)
integral pilot check and
pressure balance valve
system
40in3/mm
(650cc/min)
1 5in3 (2.50~~)
2-3.5 amps
95in. (240mm)
Type 2
12 volts (24 volts optional)
450lb.in.* (30 bar)
integral pilot check and
pressure balance valve system
80in3/min
(1300cc/min)
30in3 (5OOcc)
4-8 amps
10.5in. (265mm)

2.0 INSTALLATION
Installation of the Autohelm 6000 is
exceptionally straightforward but sound
in:;tallation is vital if the system’s high standard of
performance and reliability is to be achieved.
The course computer must be mounted in a
2.1 .l COURSE COMPUTER
protected position that is reasonably free of
vibration, Since the power amplifier dissipates
heat when the autopilot is under load, it is also
important that the mounting position should be
well ventilated and clear of the engine room,
Pclsitioning will also be influenced by the
requirement to reduce the total length of the
pc,wer cable to a minimum (see section 2.3.2).
The course computer should first be
unplugged from the connector unit after removing
V
the terminal box lid and unscrewing the two
internal retaining thumb nuts (Fig. 2). The
connector unit and the mounting spine may then
be screwed into position using the self tapping
screws provided (Fig. 3). Finally, plug the course
computer back into the connector unit to leave it
ready for connection (Fig. 4).

2.1.2 CONTROL UNITS
Both the indicating and non indicating control
units are designed for surface mounting in any
position. Both are non magnetic and may be
positioned near a steering compass if necessary.
In all cases the control units should be placed
within easy reach and view of the helmsman. As a
general rule, the non indicating control unit would
be most suitable for cockpit installation adjacent
to the helmsman. A non indicating control unit
may also be specified for the second steering
position in the flying bridge of a power vessel. The
indicating control unit is equally watertight and
can be mounted externally if preferred. An
indicating control unit can also be useful at the
navigation table where course information is
visible and course changes can be made directly
by the navigator.
A printed template is provided to assist
marking out fixing hole positions and locating the
20mm dia. drilled hole for the interconnecting
cable. After threading the interconnecting cable
through the 20mm dia. hole, the control unit is
finally screwed into position using the four self
tapping screws provided (Fig. S).Four blanking
plugs are supplied to conceal the fixing screw
recesses in the facia and these should be firmly
pressed into position to complete the installation.
The deck socket for the hand-held control unit
should be situated in a reasonably protected
position. Normally, the remote control socket will
be mounted in the cockpit area or anywhere that
a remote control facility may be required.
The remote control socket is supplied as
standard with a plug attached to the
interconnecting cable at the opposite end to
the deck socket. For use with the Autohelm
6000 the plug (not the deck socket) should
but cut off the cable which should be passed
through a 22mm dia. hole bored through the
mounting panel. The socket is then screwed
into position using the four self tapping screws
provided (Fig. 6).
Interconnecting cables from all control units
should be led back to the connector unit of the
course computer for connection to the common
control unit bus (see section 2.3.1).
Fig. 5

2.1.3 FLUXGATE COMPASS
Tlie fluxgate compass may be attached to a
cionvenient bulkhead using the self tapping
^
screws provided. Unscrew the top cap to release
the compass housing from the mounting bracket
(Fig. 7). Screw the bracket to the bulkhead using
the self tapping screws provided and finally re
aitach the compass body to the mounting
bmracket.
Correct positioning of the fluxgate is crucial if
ultimate performance from the autopilot
installation is to be achieved. The fluxgate should
ideally be positioned as near as possible to the
pitch and roll centre of the vessel in order to
minimise gimbal disturbance. The pitch and roll
centre is aenerally towards the centre of the
vessel, a little above waterline level. It is not
always possible to position the fluxgate at the
centre of pitch and roll, and if this is the case,
autopilot performance will not be unduly affected.
It is, however, very important to ensure that the
fluxgate is positioned at least .8m (2’6”) away from
the vessel’s steering compass in order to avoid
deviation of both compasses. The fluxgate must
also be positioned as far away as possible from
large iron masses, such as the engine and other
magnetic devices which may cause deviation and
reduce the sensitivity of the sensor. If any doubt
exists over magnetic suitability of the chosen site,
the position may be surveyed using a’simple
hand bearing compass. The hand bearing
compass should be fixed in the chosen position
and the vessel swung through 360”. Relative
differences in reading between the hand bearing
compass and the vessel’s main steering compass
should ideally not exceed 5” on any heading.
When the installation is complete the fluxgate
compass should be approximately aligned with
the vessel’s centre line by rotating the body until
the arrows on the joint line face the bows (Fig. 8).
I/
Fig. 8
Installation Precautions
Correct installation of the course computer
and fluxgate compass is vital to the successful
performance of the Autohelm 6000. The
installation precautions must be heeded if poor
performance or even failure of the autoprlot is to
-
be avordect.

The windvane attachment is normally mounted
centrally on the after rail where it can be sited in
clear wind on both tacks. The windvane mounting
mast is clamped to the after rail by the two ‘U’
bolts provided (Fig. 9). The windvane is
supplied as standard with a plug attached to
the interconnecting cable. For use with the
Autohelm 6000 this plug should be cut off and
the cable threaded through the mast. The
windvane head is then plugged into the top of
the mast (Fig. 10). The interconnecting cable
should be passed through the deck using the
waterproof deck gland. To fit the gland a 6mm
dia. hole should be drilled through the deck to
pass the cable through and the gland finally
screwed into position using the self tapping
screws provided (Fig. 1 1). After pulling the
interconnecting cable completely through, the
gland nut should be gently tightened to seal the
cable. The interconnecting cable can then be
led back to the course computer for final
connection (see section 2.3.1).
NB. The windvane head is supplied with the
vane detached for ease of packing. The vane is
easily assembled to the head and secured by
means of the circlip provided (Fig. 12). Care
should be taken to ensure that the small circlip
is correctly located in the groove.
Fig. 9
Fig. 10

2.” 5 AUXILIARY ALARM
Thl3 auxiliary alarm unit is waterproof and may
therefore be mounted in any position. The alarm
unit is supplied with a terminal block to connect a
two core interconnection cable to the course
computer. A 22mm hole should be bored through
the mounting panel/deck to pass through the two
way connector block and interconnecting cable
(Fig. 13).
Finally, the alarm unit should be screwed into
position using the four self tapping screws
provided. A foam seal on the alarm mounting
flange will ensure a watertight joint to the
mounting surface.
Fig. 13
2.1.6 RADIO NAVIGATION INTERFACE
The radio navigation interface will normally be
mounted close to the radio navigation receiver
(Decca or Loran) in the navstation area. It IS
fully waterproof and if desired may be mounted
extlsrnally.
A printed template is provided to assist
marking out fixing hole positions and the hole
for the interconnecting cable. After threading
the interconnecting cable through the 20mm
dia. hole the interface unit is screwed into.
position using the four self-tapping screws
provided (Fig. 14).
Four blanking plugs are provided to conceal
the fixing screw recesses and these should be
firmly pressed into position to complete the
installation.
Fig. 14
\\

2.2 DRIVE SYSTEM
The following notes describe the installation of
both the rotary, linear and hydraulic drive units.
2.2.1 ROTARY DRIVE UNIT
The rotary drive unit is coupled to the steering
mechanism by a simple chain drive. Most steering
gear manufacturers supply special autopilot drive
attachments and many include this facility as
standard. Figs. 15 and 17 show the
recommended rudder hardover to hardover
times for both planing and displacement
vessels up to 20m (60’) LOA. Figs. 16 and 18
enable the optimum chain reduction radio to be
selected for both planing and displacement
vessels. It is first necessary to determine the
number of turns of the driven sprocket when the
rudder is driven from hardover to hardover.
Example:
A 12m (40’) LOA displacement vessel requiring
two turns of the driven sprocket to drive the
rudder from hardover to hardover will require a
chain reduction ratio of approximately 3.0:1 (as
indicated by the dotted line on the chart).
NPE 1: ROTARY DRIVE CHAIN
REDUCTION RATIOS
Displacement Craft
..’
TYPE 1: HARDOVER - HARDOVER
TIME RECOMMENDATIONS
40
1
Fig. 15
METRES
Q B 10 I 11 I 12 I 13 I 14 1
FEET
III
I I
25 30 35 40
45
LOA
Planing Craft
8
9, 10 11 12; 13 14
I
FEET
I
I
III
25 30 35 40
45
iOA
LO A

It should be borne in mind that the reduction
ratios are for the average case and that vessels
broadly classified by length and hull type can vary
significantly in steering characteristics. Selection
of the correct chain reduction ratio is not over
cri,tical however, and any mismatch can be
corrected during sea trials by an adjustment to
the gain control switch on the course computer.
Standard W’ or W’ pitch chain is recommended
for the chain drive and the drive sprocket ideally
should not have less than 15 teeth. Bore and
ke!/way dimensions for the drive unit sprocket are
detailed in Fig. 19. It is essential that these bore
and keyway dimensions are strictly adhered to.
All sprockets must be keyed and grub screwed
to their shaft and finallv secured with ‘Loctite’.
The drive unit is mounted by bolting to a
substantial frame member (Fig20)The mounting
foot is secured to the drive unit by four equally
sp,aced caphead screws and may be rotated
through 90” to provide a more convenient
mounting position if required (Fig. 21). In some
TYPE 2: ROTARY DRIVE CHAIN
REDUCTION RATIOS
6.0
Displacement Craft
Fig. 17
I. ,.“< >,.-” x”.
^l”l
:

cases, it may be necessary to fabricate a special
frame to mount the drive unit. It should be noted
that chain tension can exceed 500lbs (230Kg)
and thus an extremely rigid mounting structure is
vital to maintain good chain alignment. Installation
failures frequently occur in this area and as a
general rule, it is desirable to ‘over engineer’ the
drive unit mounting. All fastenings should be
secured by lock washers.
Provision must also be made for chain
adjustment which is most easily achieved by
removable shims placed under the mounting foot
or by elongated clearance holes in the mounting
frame as illustrated in Figs. 20 and 21.
Both sprockets must be accurately aligned to
run in the same plane and correct alignment must
be carefully checked by means of a straight edge.
The gearbox may be mounted in any
convenient attitude without risk of oil leakage. In
addition, the drive sprocket may face any
direction since steering sense can be corrected
when the installation is complete by reversing the
polarity of the drive motor connection (see section
3.3.1). Finally, the cnain should be tensioned until
it is just tight and contributes negligible lost
motion to the drive system. Total lost motion
between the driven sprocket attached to the
steering system and the rudder stock should not
exceed 2% of total movement under any
circumstances. If lost motion exceeds this level it
must be corrected. otherwise steering
performance will be impaired.
3.22-3.24mm
(0.127”-0.1275”)
1
9.46-9.61 mm
(0.3725”-0.3785”) GRUB SCREW
/
dia.
12.7mm
(0.5”)
19mm
(0.75”)
I
Fig. 19

2.2.2 LINEAR DRIVE UNIT
The linear drive unit couples directly to the rudder
stock at the tiller arm radius recommended in .
Figs. 22 and 23. It is usually preferable to
couple the linear drive unit to the rudder stock
via an independent tiller arm (Edson offer a
standard fitting). In certain cases, however, it
may be possible to couple the pushrod to the
same tiller arm or rudder quadrant employed by
the main steering linkage. It is important to note
that the linear drive system can exert a thrust of
750lbs. If any doubt exists about the strength of
the existing tiller arm or rudder quadrant the
steering gear manufacturer must be consulted.
The method of bolting the pushrod ball end to
the tiller arm or rudder quadrant is illustrated in
(Fig.24). The fixing bolt supplied should be
assembled with its flange positioned between
the ball end and the tiller arm. It is vitally
important that the coupling bolt is fully
tightened and the nut locked by means of the
locking tab provided. The standard ball end
fi’tting will allow for a maximum angular
misalignment between the pushrod and the
tiller crank plane of rotation of up to 5”.
Accurate angular alignment is extremely
important and under no circumstances should
the above extreme limits be exceeded. The
body of the drive unit is mounted by bolting to a
substantial frame member (Fig.25). As a general
rule it is desireable to ‘over engineer’ the linear
drive unit’s mounting structure to ensure
reliability and maintenance of correct
alignment. An excessively flexible mount can
a!so severely impair the steering performance
of the autopilot.
It is important to ensure that the total rudder
movement is limited by the rudder stops built into
the vessel rather than the end stops of the linear
drive output.
I
IN>. blVI
TYPE 1: LINEAR DRIVE
TILLER ARM LENGTHS
s.*1 n..
..;,
~~IsPLACEMENT
_,’
METRES
I I
I
FEET
,
I
II I
25 30
,.. :35 40 45
, LOA
Fig. 22
TYPE 2: LINEAR DRIVE
TILLER ARM LENGTHS
INS. CM
3 15
k
6
14
z ‘3
y 12
% 11
2
W
3 Q
i=’
10 i
8
DISPLACEMENT
METRES
12 13 14 15 16 17 18
FEET
i
40 45 50 55 60
LO A
Fig. 23

2.2.3 HYDRAULIC DRIVE UNIT
The hydraulic drive unit should be mounted clear
of spray and the possibility of immersion in water.
It should be located as near as possible to the
hydraulic steering cylinder. It is important to bolt
the hydraulic drive unit securely to a substantial
member to avoid any possibility of vibration that
could damage the inter-connecting pipework.
There are three basic types of hydraulic
steering system, and these are illustrated in
(Fig. 26). Typical connection points for the drive
unit are shown in each case. In all cases it is
strongly recommended that the steering gear
manufacturer be consulted. The drive unit valve
block is tapped l/41) BSP to.accept suitable pipe
fittings and Dowty sealing washers are supplied.
Minimisation of hydraulic fluid loss during
connection of the drive until will help to reduce
the time and effort required later to bleed the
system of trapped air. Absolute cleanliness is
essential since even the smallest particle of
foreign matter could interfere with the correct
function of precision check valves in the steering
system.
When the installation has been completed the
hydraulic pump may be operated by switching the
control unit to ‘Auto’ and operating the +I 0” and
-10” course change buttons. Greater motor
movements will be obtained if the gain control on
the course computer is set to No. 6 and the
rudder control set to maximum.
Two Line System
The hydraulic steering system should be bled
according to the manufacturers instructions. From
time to time during the bleeding process the drive
unit should be run in both directions to clear
trapped air from the pump and inter-connecting
pipe work.
If air is left in the system the steering will feel
spongy particularly when the wheel is rotated to
the hardover position. Trapped air will severely
impair correct operation of the autopilot and the
steering system and must be removed.
During the installation of the system it has not
been necessary to keep track of the connection
sense to the hydraulic steering circuit since
operating sense of the autopilot can be corrected
if necessary by reversing the polarity of the pump
drive motor connections (see section 3.3.1).
CONNECTION OF HYDRAULIC
LINES TO PUMP
, DOWTY SEAL
,DOWTY SEAL
Fll-flNG ~ / ,‘/a” NPTFll-TlNG
Assembly for %” BSP
Line Fitting
\
ADAPTOR
Assembly for % ” NPT
Line Fitting
Two Line
Pressurised System
RESSURISED
-RESERVOIR LINE
Three Line System
RESERVOIR LINE