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Procedure for Cross Head Bearing Removal of Marine Engine – MAN B&W S50MC-C
Submitted by Anil.S on August 3, 2011 – 8:39 amNo Comment
It is very important in a large two ...view middle of the document...
12) Put blower and ventilate the crankcase thoroughly as it is an enclosed space.
13) Prepare enclosed space entry checklist.
14) After sufficient ventilation wearing proper PPE you can enter the C/C.
15) Turn the crank throw to 90° before BDC.
16) Check the bearing clearance by inserting feeler gauge b/w bearing cap and crosshead journal exactly next to the landing surface of the piston rod foot.
17) The wear limit for a cross head bearing shell is limited to 50% reduction of the oil wedge length (L).[ L=10mm]
18) Turn the crankshaft down enough to give access to nuts and screws on piston rod.
19) Mount two chain blocks on the top of the crankcase for suspending the piston rod.
20) Loosen and remove the locking wire and screws on the piston rod foot.
21) Mount the lifting eye bolt on each side of the piston rod foot.
22) Turn the crosshead to TDC.
23) Hook the chain blocks to the eye bolt on the piston rod foot. And turn the crosshead down so that piston is now suspended on the chain blocks.
24) Turn to BDC.
25) Mount the hydraulic jack on the crosshead bearing cap nut and loosen them. [pressure : 1500-1650 bars]
26) Mount the lifting attachment on the head of the connecting rod.
27) Suspend the two chain blocks from the lifting brackets in the athwart ship direction.
28) Mount the 2 eye bolts on the top of the cross head bearing cap.
29) With the help of the two chain blocks lift the bearing cap. Take it out of the engine and place it on a wooden base.
30) To check the upper bearing shell, remove the locking screws and push the shell out.
31) Mount the chain blocks to the lifting brackets on the frame box wall.
32) Turn the crosshead up until the piston rod lands on the crosshead. Ensure that the guide ring in the crosshead fits correctly in the centre hole of the piston rod.
33) Do not remove the chain blocks or the lifting eye bolts.
34) Turn the crosshead to TDC and attach the chain blocks to the lifting arrangement and haul it tight.
35) Mount the four supports for the guide shoes on the crosshead guide.
36) Carefully and slowly turn the crankshaft towards to exhaust side and make sure the crosshead guide sits on the supports.
37) Turn the crank throw towards BDC slowly while following with the chain blocks, thus continuously supporting the connecting rod.
38) In case it is necessary to remove the lower bearing shell, tilt the connecting rod towards the door on the cam shaft side with means of chain blocks.
39) Dismount the locking screws and turn the bearing shell so far up that an eye bolt can be mounted. Lift the bearing shell out.
Top clearance in crosshead bearing
Max: 0.29mm Min: 0.17mm
Video for Cross head bearing removal-
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