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Simrad Reversible Pump RPU80/160/300
12 20220422N
2 MEASUREMENTS AND CALCULATIONS FOR
APPLYING THE RPU
2.1 Calculation of cylinder volume
The RPU80 is recommended for cylinders between 80-250 cm
3
(4,9-15,2 cu. in.), RPU160 for cylinders between 160-550 cm
3
(9,8-33,5 cu.in.) and RPU300 for cylinders between 290 -960
cm
3
(17,7-58,5 cu.in.). These figures will give for a rudder angle
of 70 degrees (35°-0-35°) a hardover to hardover time of 6-20
seconds equivalent to a rudder speed of 11,6-3,5 deg./second.
Based on experience 6-8 deg./second seems to be the optimum
speed for autopilots with proportional rudder control. However,
a rudder speed between 11,6 deg./second and 3,5 deg./second
should normally cause no problem, particularly not the high
speed which will be reduced by the autopilot electronics.
Depending on type of autopilot the rudder speed is automatically
or manually adjusted during installation and commissioning.
Refer to page 1-1 and the autopilot manual for detailed
information.
The cylinder volume is calculated from the formula:
Volume =
Where
L = stroke length
D = internal cylinder diameter (= outside diameter – 0,6)
d = push rod diameter
π = 3,14
(All dimensions in centimeters)
2.2 Minimum rudder time adjustment
(Applies only for Junction units J1000B, J101A and J45A)
The minimum rudder time can be found as follows (see figure 2-
1):
Draw a horizontal line from the applicable value on the cylinder
volume axis. Rudder time may now be read on the horizontal
axis.
By means of potentiometer RV1 in the Junction unit the rudder
time can be increased.
4
)(
22
π
dDL −
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