Main bearing T 18-1/5. No. Name of article Check item 1 Jack bolt Check upper &lower face for damage 2 Column center piece

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1 Main bearing Structure Pin for fall prevention Fit plug after work is over No. Name of article Check item 1 Jack bolt Check upper &lower face for damage 2 Column center piece 3 Bearing cover Check unbalanced tightening P-S side a1-a2 =max 0.3mm 4 Vent valve 6 Set screw 7 Cylinder 8 Nut Loosen center screw for air vent. Air vent must be completed. Before dismantling, give mating mark to cylinder & nut Keep jointing face clean between cylinder and nut. 9 Slit for spanner For Mark 1.5 The bearing is numbered as No.1,No.2 Light weight type etc. from aft end. Tools (Main bearing bolt) Tools (Main bearing shell) 1 Special feeler gauge Roller support Depth gauge Removing device for 1 Port power bearing shell Press. gauge 2 Wire (1,000Kg/cm 2 ) Support Connectors & hoses Port power, HP hoses Hydraulic jack Pliers 1 Dial gauge with 1 Spanner (AF 80mm) magnet base 10 Rubber ring 11 Locking wire 12 Shim D Pressure space V Release valve 20 Main bearing 21 Crankshaft Main parts weight table (Kg) Type Bearing cover Bearing Jack bolt shell (Mark1) (No.1/Others) 948 / (Mark1.5) 770 Remarks : Mark1 type was applied on DU3159, DU3206, and Mark1.5 type was applied on the other engines. 84T 18-1/5

2 2. Check item 2-1. Overhaul Normally, every 5 years (30,000 ~ 40,000 Hrs.) It will be enough by the Classification Society's requirement, unless there are damage of white metal, overheat of main bearing, unusual deflection of crankshaft (See the section on crankshaft ) were observed. Height of bearing cover Check items at the time of main bearing overhaul 1) Measure the difference in height (between S and P side) of bearing cover. Adjusted value : Admissible difference a1-a2 Max. 0.3mm 2) Check the loosening pressure for jack bolt. Adjusted value : The tightening pressure can sometimes go down to around -10 MPa at the first overhaul, which is not abnormal. Tighten it again by regular value (=60MPa). 3) Check the upper and lower spherical surfaces of Jack bolts. If anything unusual is found about the following items, contact the engine maker after taking pictures and record of locations and sizes. Peeled segments of white metal should be kept to investigate the cause later. 4) Damage, discoloring and separation of white metal of bearing. Temporary measures : Remove white metal likely to come off and scrape around the removed boundaries slightly. 5) Worsened roughness and damage of journal surface. Temporary measures : Finish it smoothly with an oilstone and hand pad (nylon scrubbing brush). 6) Damage of shell metal back surface (fretting) Temporary measures : Remove the convex with emery cloth. By placing the shell metal on a flat face, check it for absence of twist and deformation. 84T 18-2/5

3 2-2. Points to be noted in measuring clearance of main bearing upper parts 2-3. Periodic checks 3. Overhaul / reassembly 3-1. Basic construction 3-2. History of white metal thickness and number of pin for lower metal Every 1,000 Hrs. 1) Measure the clearance of main bearing upper part with the depth gauge or feeler gauge after ensuring that the crankshaft is contacting surely on the lower bearing. (Refer to Standard inspection dimension in item 3-4 of 18-4/5 page) 2) When measuring the clearance of main bearing upper part with the depth gauge, subtract a value equal to the metal thickness stamped nearby the measuring hole of shell metal. 1) Check inside of crankcase whether falling of white metal fragment is observed. 2) Check damaged place that can be presumed by the shape of fragment. (crank / cross metal: curved surface, guide shoe: flat shape) 3) Check main bearing damage at F&A edge by using with L-shape wire bent at its end. Type Upper metal Lower metal White metal into casting cover Shell metal Thickness of white metal (mm) Type Number of History Upper metal Lower metal pin for lower metal First engine 3 3 Original 2 Revise Ditto 2 Revise Ditto 2 The engine that entered service after January, ~ ~ 3.3 Modified type 4 Original Added bore relief Modified type 284 2Pin Pin 84T 18-3/5

4 3-3. Cautions 3-4. Standard inspection dimension 4. Failure sample 4-1. Metal damage sample 1) Make sure to tighten the jack bolt after tightening the tie rod. (Loosen the tie rod after loosening the jack bolt) 2) When detaching the lower metal, never supply the hydraulic pressure of more than 60MPa(600 bar), and/or put 2 jacks on one end. (An excessive force may bend the hydraulic jack support and the runoff the jack may damage the components inside the crankcase.) The permissible pushing up height of the crankshaft is 0.1 to 0.15mm in the main bearing unit where it disassembles. 3) Admissible difference of bearing cover is to be within 0.3mm. 4) After the work is finished, provide various locking devices, and take care not to leave rag and tools behind. (Secondary accident may occur with the rotating portions. The left rag acts as one of the major causes for bearing seizure.) Main bearing jack bolt tightening force () : Tightening hydraulic pressure; 60MPa(600bar) : Loosening hydraulic pressure; 62MPa(620bar) (Unit: mm) Main bearing clearance (b1) Jack bolt Type Normal clearance Max. clearance Admissible difference a1-a ~ 0.68 Max. 0.8 Max ) Hard contact, damage or peel off of white metal around the mating face of the lower shell metal and bearing cover. Measures : Improve the formation of lube oil film by means of an improved oil groove and a modified bearing clearance. 2) Damage and peel off of specific metal in a short time due to poor alignment of engine. 3) Poor centering of cover. One-sided contact and damage in the F-A direction due to unbalanced tightening. 84T 18-4/5

5 4-2. Features of damaged metal 1) Features of white metal fragments found in the crankcase. White metal fragments with curved faces: Source : Refer the table of Thickness of white metal in page 18-3/5 for upper and lower metal Cause : Poor bonding, hydrogen blister, fatigue destruction due to overload. Foil-shaped white metal fragments: Cause : White metal foil runs out from the bearing clearance (Seizure) White metal fragment is struck and extended in the clearance between shaft and bearing. (Exfoliation) 4-3. Other damage sample 1) Fretting of the back of lower bearing shell 5. Technical information Service information DUQ1-038E Main parts where white metal is used 6. Addition 1. Main ingredients of the white metal material 2. The bearings are cast in white metal by using mold. Mark % Sn Remainder Sb Cu Cd Ni Ag Co T 18-5/5

Main bearing C 18-1/7. Remark): Both types of stud bolt and jack bolt have been adopted on the ship, which delivered before on March 2002.

Main bearing C 18-1/7. Remark): Both types of stud bolt and jack bolt have been adopted on the ship, which delivered before on March 2002. Main bearing 1132 1.1 Structure Jack bolt type Remark): Both types of stud bolt and jack bolt have been adopted on the ship, which delivered before on March 2002. 8 ~ 12Cyl Stud bolt Jack bolt No. Name