Xd By Hand Typing

Assuming that the x-hd pin and piston rod assembly is resting on the support bracket bolted to the guides and that con-rod is swung down to c/c door level ( as shown in diagram) Inspection of bearing half on con rod ( the loaded part) for evidence of---1. Scoring

: which indicates hard particles in LO or damage to x-hd pin

2. Squeezing & cracking

: points towards overloading

3. Wiping

: indicates poor lubrication and overloading.

4. Corrosive attack

: a) If the oil develops a week acid b) If the salt water content in the lube oil is higher than 1%. The water will attack the white metal, and result in formation of a very hard black tinoxide encrustation (SnO) which may scratch and roughen the pin surface.

Some manufacturer have an overlay of a tin/led alloy on the tin aluminum bearing metal, and state that the bearing should be replaced if this overlay has worn away. Other manufacturer have wedge machined in the bearing material and recommended replacement when wedge are reduced to half original width. Inspection of top half: To perform this check the con rod reconnect and engine must turn to BDC and top cover lifted. Inspection of x-hd pin: Inspect closely under side of the pin as it is continuously the loded part. The surface finish should be mirror finish like no evidence of scoring or roughness. If any is found then pin must be replaced or polished as per manufacturer recommendation. X-hd is not hydro dynamically lubricated , so care must be taken as damaged pin will damage the bearing metarial. Roughness of crosshead pins: a) New or repolished : 0.05 Ra b) Acceptable in service : 0.05-0.1 Ra c) Repolishing if over : 0.1 Ra Average bearing wear rate is 0.01 mm/10,000 hrs. As long as the wear rate is in the region of this value, the bearing function can be regarded as normal. •

Check the guide shoe and guide stripe for evidence of squeezed out of metal

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Also check the sump pan for any white metal

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If any dout to the condition of the guide shoes, then con rod must be removed and pin must be lowered to the C/S so that guide shoe can be examined.

These defect can be minimized with correct operation and maintenance as follows: Operation of engine: 1. Do not overload engine 2. Blow throw engine (keep indicator cocks open) before starting to avoid any hydraulic locking due fuel or water leakage to cylinders. 3. Maintain proper lubricating oil temp and pressure on running gear to avoid seizure. 4. Do not run bearing with high temperature 5. Do not operate on critical RPM 6. Maintain correct fuel injection timing. Early injection cause rapid rise of pressure which casing sock load which may damage both bearing and journal 7. Maintain proper power blanching Maintenance: 1. Maintain the filterization of LO to aboid any abrasive particle in the system. 2. Send the Lo for laboratory analysis. And act accordingly 3. Beside this carry on board LO test at regular interval. 4. Aboid any aciudic condition. Of Lo to prevent acidic corrosion. 5. Check the bearing clearances at regular interval. 6. Check the Lo flow and jets from the bearing at regular interval.