The bedplate is single-walled and arranged with an integral thrust
bearing housing at the aft end . Cross members are steel
fabrications although the centre section, incorporating the main bearing
saddle tie-bolt housings, may be a steel forging. To resist crankshaft
loading and transverse bending, the main bearing keeps are held down
Fig: Sulzer RTA72U diesel engine
The crankcase chamber is arranged by using individual A-frames for
columns which are also the mountings for the double-slippered
crosshead guides. The A-frames are joined together by heavy steel plates
and short angle girders to form a sturdy box frame. The A-frames in
way of the thrust block are manufactured as a one-piece double column
to ensure accurate mesh of the camshaft drive gears which are enclosed
in this section.
Individual cast-iron cylinder blocks are bolted together to form a rigid
unit which is mounted onto the A-frames. Tie bolts extend from the top
of the cylinder block to the underside of the main bearing saddles.
The crankshaft is semi-built, with the combined crankpin and
crankweb elements forged from a single element. The journal pins are
then shrunk into the crankwebs.
For all but the larger numbers of
engine cylinders, the crankshaft is a single unit. The main journal and
bottom-end bearings are thin-walled shells lined with white metal. The
forged connecting rod has a 'table top' upper end for the mounting of
the crosshead bearing. A large crosshead, with floating slippers at each
end, is used. The piston rod is bolted directly to the top of the crosshead
pin. The pistons are oil-cooled and somewhat shorter in length than
earlier designs. There is no piston skirt. Five piston rings are fitted
which are designed to rotate within their grooves.
Cylinder liners have a simple, rotationally symmetrical design with the
scavenge ports at the lower end. The deep collar at the upper end is
bore-cooled, as are all components surrounding the combustion
chamber. Cooling water is fed from below through a water guide
arranged around the liner.
Cylinder lubrication is provided by eight
quills arranged around the lower edge of the collar on the liner. The
more recently introduced RTA series engines all have oil-cooled pistons
with oil supplied from the crosshead bearing up through the piston
A piston rod gland separates the crankcase chamber from the under
piston space. Various scraper and sealing rings are Fitted within the
The cylinder head is a single steel forging arranged for bore cooling
with appropriately drilled holes. Pockets are cut for the air starting valve
and fuel injection valves, the number depending upon the cylinder bore.
The centrally mounted exhaust valve is fitted in a cage with a
bore-cooled valve seat.
The valve stem is fitted with a vane-type impeller
to ensure valve rotation. The valve is opened by hydraulic pressure from
pumps driven by the camshaft and closed by compressed air.
The camshaft is located at engine mid-height and is gear driven from
The initial gear drive is bolted to the rim of the thrust
block and a single intermediate wheel is used. On larger-bore,
high-powered engines the gear drive is in the centre of the engine. The
camshaft extends the length of the engine and each individual segment
carries the exhaust valve actuating and fuel-injection pumps plus the
reversing servo motor for one pair of cylinders.
Constant-pressure turbocharging is used, and electrically driven
blowers cut in automatically when the engine load is at about 40% of the
maximum continuous rating.
Lubricating oil is supplied to a low- and a medium-pressure system.
The low-pressure system supplies the main and other bearings. The
crosshead bearing, reversing servo motors and exhaust valve actuators
are supplied by the medium-pressure system. Cylinder oil is supplied to
lubricators from a high-level service tank.
Double valve controlled, variable injection timing is used to deliver
fuel to multiple, uncooled injectors and an electronic governor is
supplied as standard.
Where the engine has oil-cooled pistols they will
be supplied from the lubricating oil system, possibly at a higher pressure
produced by booster pumps, e.g. the Sulzer RTA engine. An appropriate
type of lubricating oil must be used for oil-lubricated pistons in order to
avoid carbon deposits on the hotter parts of the system.
Four stroke cycle diesel engines operational guideline
MAN B&W diesel engine - Basic principles and operational guideline
Four stroke cycle diesel engines
The fuel oil system for a diesel engine
Function of fuel injector
Lubricating oil system for a marine diesel engine
Fresh water & sea water cooling system
Two stroke cycle diesel engines
Dealing scavange fires
Heat exchanger for running machinery
Starting air system for diesel engine
Power measurement -Engine indicator
Sea water circulation of coolers
Function of governors
MAN B&W diesel engine
Couplings, clutches and gearboxes of a marine diesel engine
Explosion relief valve
Cylinder relief valve
Diesel engine Turning gear
Crankcase oil mist detector
Marine machineries - Useful tags
Marine diesel engines
||Steam generating plant
||Air conditioning system
||Emergency power supply
||Exhaust gas heat exchangers
||Feed extraction pump
|| Four stroke engines
|| Fuel injector
|| Fuel oil system
|| Fuel oil treatment
Lub oil filters
MAN B&W engine
Oily water separator
Overspeed protection devices
Piston & piston rings
Sewage treatment plant
Starting air system
Two stroke engines
Drydocking & major repairs
Deck machineries & cargo gears
|| Control and instrumentation
||Engine room safety