FUEL SYSTEM - N.10
Troubles in Service
The first symptoms of atomiser troubles usually fail
in one or more of the following headings:–
1.
Misfiring.
2.
Knocking in one (or more) cylinders.
3.
Engine overheating.
4.
Loss of power.
5.
Smoky exhaust (black).
6.
Increased fuel consumption.
Often the particular atomiser or atomisers causing
trouble may be determined by releasing the pipe union
nut on each atomiser in turn, with the engine running at
a fast "tick-over." This will prevent fuel being pumped
through the nozzle to the engine cylinder, thereby
altering the engine revolutions. If after slackening a pipe
union nut the engine revolutions remain constant, this
denotes a faulty atomiser.
After stopping the engine the nuts from the flange of
the doubtful atomiser should be removed and the
complete unit withdrawn from the cylinder head and
turned round, atomiser nozzle outwards and the unions
retightened. After slackening the unions of the other
atomiser pipes (to avoid the possibility of the engine
starting), the engine should be turned until the nozzle
sprays into the air, when it will be seen at once if the
spray is in order. If the spray is unduly "wet" or "streaky"
or obviously to one side, or the atomiser nozzle
"dribbles," remove from the fuel pipe; the faulty atomiser
should then be securely wrapped, preferably in grease-
proof paper for attention on the maintenance bench.
NOTE: Great care should he taken to prevent the
hands or face from coming into contact with the
spray, as the working pressure will cause the fuel oil
to penetrate the skin with ease.
Preparation
The most suitable bench for atomiser maintenance
is one that is zinc, linoleum or plastic covered, absolutely
free from dust, dirt, filings, grease or acids, where no
other work is done and where the use of cotton waste or
fluffy rags is forbidden. It should also be provided with a
small vice (the jaws being protected with clean soft
copper or aluminum shields) and a dust-proof drawer for
holding the nozzle cleaning tools.
An atomiser is good for service if, when operating
the Atomiser Testing Pump at the recommended rate, it
gives four effective sprays, each breaking into a very fine
mist and the breaking pressure is not less than the
working pressure, (refer page B.12) then the atomiser
may be put back into service.
Fig. N.15.
Exploded view of Atomiser.
1.
Nozzle Holder Cap Nut.
7.
Spindle.
2.
Cap Nut Washer.
8.
Body.
3.
Locknut.
9.
Nozzle Needle.
4.
Spring Cap.
10.
Nozzle.
5.
Identification Tab Washer. 11.
Nozzle Cap Nut.
6.
Spring.
12.
Copper Washer.
