WÄRTSILÄ Vasa R22, Instruction Manual

Page: 272 / 297

22.5.4 Maintenance
•
remove the tripping mechanism by removing the screws (13)
and (11), Fig 22-6,
•
remove the spindle (4) with piston and spring (5).
Be very careful when removing the spring (5). Use the tool
837015.
1 Check all moving parts for wear and replace by new
ones, if necessary.
2 Check the drain hole (12) to be open.
3 Tighten the screws (11) to torque according to chapter
07. when assembling and lock with steel wire.
4 Tighten the screws (13) to torque according to chapter
07.
5 Use tool 837015 when mounting the spring.
6 Check the tripping speed according to section 22.5.2.
22.6 Electro-pneumatic overspeed trip
device
22.6.1 Description
The overspeed trip device is electronically controlled. Starting air
of maximum 30 bar is used as operating medium. The tripping
speed is according to chapter 06., section 06.1.
There are two separate air inlets, one for starting air and one for
the electro-pneumatic overspeed trip device. The line for the electro-
pneumatic overspeed trip device is provided with a non-return valve
(1), Fig 22-2, and an air vessel (4) large enough to make it possible
to stop the engine even if the air pressure before the non-return valve
disappears.
The three-way solenoid valve (5) gets the stop signal for over-
speed from the electronic speed measuring system. Besides, the
solenoid is also connected to the stop system.
When the solenoid valve opens, air is fed to the pneumatic
cylinders, one for each injection pump. The piston (6) of the air
cylinder actuates the fuel rack, moving it to stop position.
The stop signal is normally energized long enough to stop the
engine completely. When de-energized, the air is evacuated through
the three-way valve and the piston is forced back to the end position
by the fuel rack.
22-9601 Control Mechanism 22
VASA 22 22 - 11