WÄRTSILÄ PAAE051728, Instruction Manual

Page: 319 / 394

21.2.2 Maintenance
1 Remove the main starting valve
from the engine.
2 Remove the hexagon socket head screws
and remove
the pilot valve assembly.
3 Remove the pilot valve piston (22).
4 Clean the pilot valve
of any dirt which may block the
small air passages and holes.
5 Check all O-rings
in the pilot valve and replace if they
have developed flat, become hard and brittle or been damaged
in any way. Lubricate the O-rings with oil.
6 Remove the power piston (24)
and check the O-ring. En-
sure that the small vent hole to atmosphere in the cylinder
under the piston is clear.
7 When reassembling the valve
ensure that the air pas-
sage hole in the upper body flange lines up with the hole in the
lower body.
8 Remove the flange (27),
spring (26) and main valve seat
complete with the valve stem (25). Examine O-rings as in step
5 above.
21.3 Starting air distributor
21.3.1 Description (Fig 21-1)
The starting air distributor is of the piston type with precision
machined interchangeable liners (16). The liners as well as the
pistons are of corrosion resistant materials. The distributor pis-
tons are controlled by a cam at the camshaft end. When the main
starting valve opens, the control pistons (15) are pressed against
the cam, whereby the control piston for that engine cylinder,
which is in starting position, admits control air to the power
piston (33) of the starting valve, see Fig 21-3. The starting valve
opens and allows pressure air to pass into the engine cylinder.
The procedure will be repeated as long as the main starting
valve is open or until the engine speed is so high that the engine
fires.
After the main starting valve has closed, the pressure drops
quickly and the springs (14) lift the pistons off the cam, which
means that the pistons touch the cam only during the starting
cycle, and thus the wear is insignificant.
32-200202-01 Starting Air System 21
WÄRTSILÄ 32 21 - 3