Lewmar Integra Autopilot Drive Product Manual page 5

3.4 Constellation chain and sprockets
Fig 3.4
20 mm
5 mm
C
Chain size
The chain kit, 5/8" pitch is suitable for most applications.
Sprocket sizes
To stop the drive sprocket rotating on the drive sha , the sha has a 5 mm square key that fits into a keyway at
the centre of the sprocket. Use only Lewmar approved drive sprockets, its bore and keyway dimensions must fall
within the ranges specified in Fig.3.4 for it to lock correctly to the drive sha .
Sprocket for steering sha
If the steering shaft does not already have a second, or assigned, autopilot sprocket then an additional
sprocket will be required, size 5/8" pitch, number of teeth to be determined depending upon steering system.
Due to the large variation in sprocket sizes, Lewmar recommends obtaining a steering sprocket from the
steering manufacturer. The sprocket will have to be attached to the steering shaft, in vertical alignment to the
sprocket on the autopilot drive.
To determine the sprocket size required for the steering sha , follow this procedure:
Count the number of times the steering shaft turns when the rudder is moved from hard over to hard over.
Use the table 3.4 (above) to determine the sprocket size required at the steering shaft by matching number of
turns hard over to hard over.
Note:
The Integra drive unit is supplied with a chain kit suitable for a sprocket centre distance of 560- 600mm. If the
distance between your two sprockets is greater you will need to increase the chain length by inserting extra
links.
The sprocket sizes shown in table 3.4 provide good steering performance for most boats. If you think your
boat may have unusual steering characteristics, contact Lewmar's Technical Services or an authorized service
representative for advice.
The additional sprocket must be keyed and screwed to the shaft with a grub screw and secured with thread-
locking compound.
A
25 mm
B
A. Bore
0.312"
B. Keyway
C. 1.8" PCD - 9 tooth, 5/8" pitch
Lewmar Integra Autopilot Drive Manual ref B10420 iss.1
NUMBER OF STANDARD
TURNS LOCK TO DRIVING SPROKET
LOCK NUMBER OF TEETH
1
1.2 9
1.5
DRIVEN SPROCKET
NUMBER OF TEETH
15
13
11
Table 3.4
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