Page 64 - Introduction to Marine Engineering

Diesel engines 51

controllable-pitch propellers are used then engine reversing is not
necessary. A general procedure is now given for engine operation which
details the main points in their correct sequence. Where a manufactur-
er's instruction book is available this should be consulted and used.

Preparations for standby

1. Before a large diesel is started it must be warmed through by
circulating hot water through the jackets, etc. This will enable the
various engine parts to expand in relation to one another.
2. The various supply tanks, filters, valves and drains are all to be
checked.
3. The lubricating oil pumps and circulating water pumps are started
and all the visible returns should be observed.
4. All control equipment and alarms should be examined for correct
operation.
5. The indicator cocks are opened, the turning gear engaged and the
engine turned through several complete revolutions. In this way any
water which may have collected in the cylinders will be forced out.
6. The fuel oil system is checked and circulated with hot oil.
7. Auxiliary scavenge blowers, if manually operated, should be started.
8. The turning gear is removed and if possible the engine should be
turned over on air before closing the indicator cocks.
9. The engine is now available for standby.
The length of time involved in these preparations will depend upon the
size of the engine.

Engine starting

1. The direction handle is positioned ahead or astern. This handle may
be built into the telegraph reply lever. The camshaft is thus
positioned relative to the crankshaft to operate the various cams for
fuel injection, valve operation, etc.
2. The manoeuvring handle is moved to 'start'. This will admit
compressed air into the cylinders in the correct sequence to turn the
engine in the desired direction.A separate air start button may be
used.
3. When the engine reaches its firing speed the manoeuvring handle is
moved to the running position. Fuel is admitted and the combustion
process will accelerate the engine and starting air admission will
cease.