THIS KIND OF DAMAGE MANIFEST ITSELF BY PARTS OF THE OVERLAY ND/ OR WHITE METAL CONTACT FACE BEING WIPED OUT, SO THAT OIL GROOVES IN EXTREME CASES DISAPPEAR.
CAUSE:-
PROVIDED ADEQUATE OIL SUPPLY HAS BEEN MAINTAINED, THE DAMAGE CAN ALWAYS BE ASCRIBED TO A TOO HIGH DEGREE OF ROUGHNESS OF THE CROSSHEAD JOURNAL SURFACE. THE CAUSE OF EXCESSIVE JOURNAL ROUGHNESS MAY BE AN ORIGINAL DEFECT IN WORKMANSHIP, SUBSEQUENT MECHANICAL OR CORROSIVE DAMAGE OF THE SURFACE DURING TRANSPORTATION, STORAGE, OR HARD PARTICLES IN THE LUBE OIL. THE ROUGHNESS CAN ALSO ARISE LATER BY CORROSION DURING THE OPERATIVE PERIOD OF THE ENGINE IF THE LUBE OIL DEVELOPS WEAK ACIDS OR IF STRONG ACID- ANHYDRIDES ARE ADDED TO IT, WHICH , WHEN COMBINED WITH WATER IN OIL DEVELOPS ACID.
REPAIRS ON THE SPOT :-
SLIGHT DAMAGE CAN BE REPAIRED BY LIGHT SCRAPING. FOR EXAMPLE IN THE CASE OF SLIGHT WIPING OF THE OVERLAY OR THE WHITE METAL IN THE WEDGE-SHAPED OIL GROOVES, THESE CAN BE RE-ESTABLISHED BY MEANS OF A SCRAPER. IN GENERAL, IT IS RECOMMENDED TO REPLACE DAMAGE SHELLS.
THE JOURNAL IS POLISHED ON THE SPOT WITH A HEMP STRING AND POLISHING WAX. A CLEAN, SOFT HEMP STRING, POSSIBLE BRAIDED , OF ABOUT THREE QUARTERS OF AN INCH THICKNESS IS WRAPPED TWICE ROUND THE JOURNAL AND IS PULLED TO AND FROM UNTIL THE COIN TEST PROVES THE SURFACE TO BE ADEQUATELY SMOOTH.
POLISHING WAX AND GAS OIL FORMING AN ABRASIVE PASTE OF A SUITABLY SOFT CONSISTENCY, ARE TO BE APPLIED TO THE HEMP STRING AT REGULAR INTERVAL. LET THE STRING TRAVEL SLOWLY FROM ONE JOURNAL END TO OTHER DURING THE GRINDING.