Bosch Rexroth Marex SB, Руководство пользователя

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27
General
Overview
Wiring
Operation
Error Analysis
Appendix
Adjustment
Conditions when reversing from ahead to astern:
When reversing from ahead to astern, the gearing is at first shifted to neutral, the shaft is disengaged
from the engine (1). As the ship continues to move ahead, the propeller is driven like a windmill by the
water streaming against it so that the shaft continues to turn. When the gears are then shifted to
astern, the engine must work against the shaft which is still turning. In an unfavourable case, the
engine might stall.
engine
engine
1 gears neutral
2 gears astern
ship -
velocity
ship -
veloccity
neutral
astern
shaft speed depends
on ship velocity
engine speed shaft speed works
against engine speed
To avoid stalling the engine, the control can wait an adjustable time (reversing delay time) before
reversing. The delay time depends on the given lever position of the control head.
The reversing delay time must be determined experimentally during a sea trial. For this, the ship must
accelerate from 1
st
detent ahead to full ahead. The time, the ship needs to reach 2/3 of its maximum
speed, has to be preset as reversing delay time. Afterwards, reversing maneuvers need to be carried
out covering the full speed range.
!
During the reversing maneuvers, start with a slow speed first and increase gently.
If necessary, the reversing delay time must be adjusted (lengthened, if the engine
revolutions drop too heavily or shortened if no deceleration of the engine speed is
recognisable.
If the reversing delay time is too short, clutch, gearing and engine may be
damaged, if it is too long, the manoeuvrability may be restricted.
nominal speed
ahead
nominal position gears
time
time
idle speed
power boost
reversing delay time
TIME
1
2
3
4
5
6
7
8
delay time before clutch
reversing delay time
delay time after clutch
TIME reversing delay time
1
2
3
4
5
6
7
8
5
0 s 1 s 2 s 3 s
astern
4 s 5 s 6 s 7 s 8 s 9 s 10 s 11 s 12 s 13 s 14 s 15 s
For applications with 2 control units, only the portside system must be adjusted.