Instructions for k GF type engines ; edition 4

The lower part of the cylinder cover has eight tangential, inter-connected cooling water bores which are closed from the outside by means of plug screws.Cooling water is supplied from th

INSTRUCTIONS FOR

The purpose of this book is to provide general information about the design, themaintenance, and the dismantling af B&W 2-stroke, crasshead engines.

The contents have been prepared on the basis of engine type K90-F, but thebook should not be taken to apply to any specific engine

The descriptions printed on yellow paper are alternative designs

All references to this instruction book should include title, edition No., andpossibly page No

Example: Instructions for K GF Type Engines, edition 4, page 901.02-01

This book is subject to copyright protection The book must not, either wholly

or partly, be copied, reproduced, mode public or in any other way modeavailable to a third part without written consent to this effect from Burmeister

& Wain Engineering Company Limited

B&W Engineering

R,:search, Design & Development

2, Tarvegode DK - 1400 Copenhagen K Denmark

Cables: bwengineering Telex: 31365 bumei dk Telephone: +45 1 542501

901.01 - 01

CYLINDER COVER

The cylinder cover is mode of mild steel and has a centre bore for the exhaustvalve which is attached by means of four studs The cover furthermore has threebores for the fuel valves, which are resiliently mounted by means of springhousings with disc springs under the nuts of the studs Other bores have beenprovided to accommodate starting valve, starting air pipe, safety valve andindicator valve

The lower part of the cylinder cover has eight tangential, inter-connected

cooling water bores which are closed from the outside by means of plug screws.Cooling water is supplied from the cylinder block through four cooling waterconnections to the tangential bores and is thence passed to an annular duct K

at the periphery of the cover From the duct K the water is passed throughrodial bores on the entire circumference of the cover to another annular duct Hsituated at the exhaust valve bore and on through cooling water connections tothe exhaust val ve proper

In oddition to the four cooling water connections mentioned before there is afifth connection between the cylinder block and cover, leading some of the

HYDRAULIC RING FOR CYLINDER COVER

The cylinder cover is tightened against the tQP of the cylinder liner by means

of nuts and studs fitted in the cylinder block On top of the cylinder cover islocated a steel ring incorporating a hydraulic tightening device for each of thecover attachment studs The cylinders of the tightening devices are arranged asbores in this ring, inter-connected through bored oil ducts Each cylinder isequipped with a ring-shaped piston and two sealing rings

The cylinder cover nuts each consist of an inner nut fitted on the cover studand bearing against the piston of the tightening device, and an outer ring-shaped nut suiting the external thread of the inner nut

When tightening the cover, the inner nut, and thus the piston of the tighteningdevice, is screwed up with the aid of a face spanner When hydraulic pressure

is cppl ied to the system, the piston of the tightening device is pressed upwardsresulting in the cover stud being slightly lengthened, following which the outerring-shaped nut can be screwed up with a tommy bar When the system isrelieved of hydraulic pressure, the tightening pressure is transmitted to the outer

nut.

Between two of the tightening devices at the manoeuvring side of the engine isfitted a snap-on coupling for connection of the hydraulic high-pressure pump.Between the other devices there are bl eed screws that are to be opened when

fj IIi ng and' venti ng the system

The hydraul ic ring is attached to the cyl inder cover by means of four eye

screws which are also used when lifting the cover The ring proper can beIifted by removing the eye screws and fitting some larger eye screws that fit

an internal thread in the holes However, the ring is not usually to be

sepa-from the studs.

2 Position the extractor tool and secu'e to the starting valve flange by means

5. If requi red, reface the seating surface using the cutter supplied

6 Grind the seating surface with Carborumdum No 200 and the grinding disc,which is to be fitted on the tool spindle in place of the cutter

7 Clean the valve bore and inspect the seating

8 Fit a union for control air supply to the valve housing Also fit two new0-rings, lubricated with little oil

9 Insert the starting valve in the cylinder caver and tighten the nuts with torquespanner to the value indicated in the I Data I section.

When inserting starting valve studs, also tighten with a torque spanner as

seats

2 The taal for reconditioning the valve bores consists of a common spindle with

a handle and, for the fuel valve bores, of a guide, carban cutter, seating facecutter, and a grinding mandrel Far the starting valve bores: a guide, a seatingface cutter, and a grinding disc

3 C lean the fuel valve bores, using the carbon cutter

4 If required, recondition the tapered seating far the fuel valve using the

appro-priate cutter

5 Grind the seating by means of the grinding mandrel and Carborundum No. 200.

6 After the grinding, clean the seating carefully, and check

7. C lean the starting valve bores in the cylinder cover and examine the seating

surface for the starting valve

8. If required, reface the seating surface by means of the appropriate cutter.

9. Grind the seating surface by means of the grinding disc and Carborundum No.200.

10 Carefully clean and inspect the seating

1l Clean and inspect the seating for the exhaust valve in the cylinder cover.

12 Grind the seating by means of the grinding disc and Carborundum No. 200;

clean and inspect

13 Lift up the cylinder cover by means of the crane, wipe clean and examine thecontact face against the cylinder liner

14 If the contact face of the cover is to be ground, remove the distributing piece

as well as all fuel valve and exhaust valve studs Also remove all cooling

15 Remove the eye screws which secure the hydraulic ring to the cylinder cover.

Fit eye screws for lifting of the ring in the threaded holes and lift the ring

away using the lifting tools for the cylinder cover, and the era ne

16-17. Pass a length of rope through two holes in the cover, as shown, and invert thecover on a couple of wooden blocks

18. Grind the contact face of the cover by means of the grinding machine, according

to the separate instructions

;

.

.

PISTON AND PISTON ROD

The piston consists of three main parts: Piston crown, cooling element, and

At the top, the piston crown has a groove for fitting of tools when lifting thepiston and, besides, the piston crown is provided with chromium-plated groovesfor 5 piston rings All the piston rings have oblique cuts - 3 have right-hand,and 2 left-hand cuts

The piston rod has a through-going bore for the cooling oil outlet pipe, which

is secured to the funnel of the cooling element The cooling oil is supplied

through a telescopic pipe connection on the crosshead and passes through a

bore in the foot of the piston rod and on through the bore in the piston rod tothe cooling element

Four angled bores in the cooling element give the cooling oil a rotary ment inside the piston crown The oil is passed on through a number of milledgrooves in the upper edge of the cooling element to the funnel and the outletpipe in the piston rod From a bore in the piston rod foot the oil is led through

move-a dischmove-arge spout to a slotted pipe on the engine frame and past a sight glass

on the crankcase

The piston rod foot rests on the crosshead, guided by two guide pins The

rod is secured to the crosshead by a stud which is screwed into the rod andwhich has a thread for the piston rod nut and a special tool attachment thread

902.02 - 00

PISTON ROD STUFFING BOX

In the bore for the piston rod in the bottOl1' of the scavenge air box a stuffingbox is mounted to prevent Iubri cati ng oil from bei ng drawn up from the crankcaseinto the scavenge air space The stuffing box also prevents scavenge air fromleaking into the crankcase

The stuffing box is mounted on a ring which is screwed on to the underside ofthe bottom of the scavenge air box The stuffing box is taken out together withthe piston rod during overhaul of the piston, but can also be disassembled forinspection in the crankcase with the piston remaining in position in the engine.The stuffing box housing is in two parts, assembled by a flanged joint In thehousing five ring grooves have been machined out, of which the two uppermostones accommodate sealing rings that prevent scavenge air from blowing downalong the piston rod In the three lowermost grooves scraper rings are fittedwhich scrape the lubricating oil off the piston rod The oil is led throughbores in the housi ng and bock to the crankcase

Between the two uppermost ring grooves, for the sealing rings, and the threelowermost grooves, for the scraper rings, a cofferdam has been machined outwhich, through a bore in the housi ng and a connecti ng pi pe, communi cateswith a control cock on the outside of the engine It can be checked byopening this control cock that sealing rings and scraper rings are functioningproperly; if air escapes, the sealing rings are defective, whereas outflow ofoil means defective scraper rings

The two sealing rings each consist of a four-piece bose ring which accommodateseight sealing segments, guided by four cylindrical pins The parts are heldtogether round the piston rod by means of a helical spring fitted in a groovethat is machined out on the outside of the bose ring

The three scraper rings each consist of a tripartite bose ring In each ringsection two grooves are machined out, and in each of these there is a pres-sed-in laminar piece with a scraping edge facing the piston rod Scraped-offoil is led away through bores in bose ring and stuffing box housing and returned

to the crankcase

Like the seal ing ri ngs, the scraper ri ngs are pressed agai nst the piston rod bythe action of a helical spring fitted in an external groove on the base ring.The gaps at the ends of the sealing and scraper ring sections ensure that the

3 Remove the drain oil pipe and two of the innermost screws from the stuffing

box flonge

4 Place the pulling tool round the piston rod

5 Attach the tool to the stuffing box and tighten round the piston rod Remove allthe outermost screws from the stuffing box f!ange

6 Lower the flange on to the lugs of the pulling tool

7-8 Turr ;·he crosshead ta BDC thereby withdrawing the tuffing box from the crankcasetop "late

9 Mount the worktable on the piston rod between the stuffing box and the flange

10 Release the pulling tool from the stuffing box housing, push the rubber ri ng on

to th" piston rod, and take out the fitted bolts from the stuffing box housing

1l Pull the two halves of the housing apart on the worktable

12 Press down all sealing and scraper rings against the worktable

13 Mount the brass cone (2/2) on top of the topmost ring

14 Slip the springs retaining the rings on to the brass cone

15 Take off the ri ng segments and stack in the correct order

16 Take out the lamellae from the scraper rings by means of a screwdriver

17-18 Press new lamellae into position in the segments

19 Remove the sharp corners of the lamellae by pulling the segments back and

forth a few times over a piece of fine emery cloth that is held round the

piston rod

20 Coat the piston rod with molybdenum disulphide •

21 Position the scraper and sealing rings in the correct order round the piston rod.Push the brass cone down on to the topmost ring and slip the springs into

position

22 Remove the brass cone

23 Position the rings at the correct height according to the template supplied

:::

.• 24 Slide the hal'les of the stuffing box housing into position round the rings

.•

Insert and tighten fitted baits Slide the rubber ring into position and

lubricate with a little oil Attach again the pulling tool to the stuffing

box housing

26 Remove the worktable

27-28 Turn the cross head upwards until the stufEing box has been replaced in

position in the crankcase top

29 Raise the flange up to the crankcase top

30 Insert, tighten and lock the inner and outer screws in the flange. Connect

the drain oil pipe

3l Remove the pulling tool, and insert, tighten and lock the last two screws

of the inner row

32 Grease the piston rod with molybdenum disulphide and turn the engine

through a couple of revolutions

33 Start the engine and keep it running for about 15 minutes at approx. 40 rpm.Ther, stop the engine and inspect the piston rod and stuffing box

,

CYLINDER BLOCK

The C),linder section of the engine consists of a number of cylinder blocks

-one for each cylinder - which are tightened together with the engine frame

and the bedplate by means of through-going tie bolts The cylinder blocks

are arranged in two graups - one on each side of the chain casing - and aretightened together by fitted bolts in the vertical loints

Two central bores, one at the top and one half-way down inside the cylinder

block, enclose the cylinder liner The upper part of the cylinder block formsthe cooling water space around the upper port of the cylinder liner, whereas

the lower port forms the scavenge air space, A central bore in the bottom ofthe cylinder block encloses the piston rod stuffing box The bottom is double

with a hollow space through which the cooling water of the engine is circulated

On the back of the cylinder block there is a circular opening leading into

the longitudinal scavenge air receiver of the engine Furthermore, the cylinderblock is provided with cleaning and inspection covers for the cooling water

and scavenge air spaces At the bock of the cylinder block there is an inlet

pipe for cooling and lubricating oil

The cylinder"liner is tightened against the top of the cylinder block by the

cylinder cover and is guided by the bore half-way down inside the block,

so that it can expand freely downwards when heated during the running of theengine Sealing against leakage af cooling water and scavenge air is obtained

by means af four silicane rubber rings located in machined grooves in the guide

of the cylinder liner, - two for cooling water and two for scavenge air

The part of the cylinder liner which is uppermost in the scavenge air space ofthe cylinder block is provided with a number of scavenge air ports, which areuncovered by the piston when this is in its lower position The scavenge ajr

ports are bored at an oblique angle to the axis of the cylinder liner so as togive the scavenge air a rotary movement in the cylinder

In the free port of the cylinder liner between the cooling water and scavenge

air spaces there are a number of bores with non-return valves for supply of

lubricating oil to the cylinder On the working face of the cylinder the boresare connected to zigzagging lubricating grooves to ensure an even distribution

of the oil

The flange of the cylinder liner is cooled by means of water circulated through