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
offer a
standard fitting). In certain cases, however, it
may be possible to couple the
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
ball end to
the tiller arm or rudder quadrant is illustrated in
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
will allow for a maximum angular
misalignment between the
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
TYPE
1: LINEAR DRIVE
TILLER ARM LENGTHS
METRES
FEET
I
I
2 5
30
40
45
,
Fig. 22
TYPE
2: LINEAR DRIVE
TILLER ARM LENGTHS
INS. CM
1 5
1 4
1 2
11
W
Q
10
DISPLACEMENT
METRES
1 2
1 3
1 4
1 5
1 6
1 8
FEET
4 0
4 5
5 0
55
6 0
LO A
Fig. 23
