WÄRTSILÄ Vasa R22, Instruction Manual

Page: 275 / 297

2 Check that correct limitation is achieved
during the
acceleration period.
3 The limitation is cut off when 100 RPM below the nominal
speed delayed with two seconds. This can be checked by in-
creasing the speed very slowly above the cutoff speed by turn-
ing slowly the speed control knob of the governor. On main
engines a cutoff speed lower than the minimum running speed
is applied.
22.7.4 Maintenance
1 If limitation gradually retires before the three-way sole-
noid valve (4), Fig 22-4, releases the pressure through the
nozzle (5), it can depend on:
•
leaky piston (1). Replace the sealing by a new one. Take care
not to deform the teflon ring outside the O-ring more than
necessary. Apply a few drops of lubricating oil on piston
before assembly,
•
the non-return valve (8) does not close. Dismantle the valve
and clean. If the valve does not, however, keep tight, replace
it by a new one,
•
leaky three-way valve.
2 If the valve does not receive voltage or receives volt-
age during wrong periods, check the control relays. See wiring
diagram and manufacturers instruction, chapter 23.
3 If the limiter does not work, check the coil (6). If the coil
(6) is undamaged, check that the cylinder (2), three-way valve
(4) or the non-return valve (8) does not stick.
4 The three-way valve requires normally no maintenance.
If the coil has broken, e.g. due to overvoltage, replace the coil
by a new one. If the valve is probable to be blocked by dirt, it
can be dismantled for cleaning provided that special care is
taken. Do not damage the sealing faces. Check that all parts
are mounted correctly. If further troubles, replace the valve by
a new one.
5 Check according to section 22.7.2 and 22.7.3.
22 Control Mechanism 22-9601
22 - 14 VASA 22