Lubrication of Chain Drive
Special attention to be paid to the securing of the lubricating oil pipes and spray nozzles. The spray nozzles must be directed so that the oil jets correctly hit the side bars. During operation, the functioning of the spray nozzles must be periodically checked and the nozzles cleaned if necessary.
Maintenance of Chain Drive
The chain drive is to be checked at the prescribed intervals given in the manual. At overhauls, the chain must be examined for signs of damage, such as cracks in the wheels or side bars, jamming links, pitted wheels, traces of blows on the outer parts on account of catching, or scoring on the insides of the side bars, due to poorly aligned sprocket wheels. The causes of these defects must be put right immediately. Damaged or broken chains must be replaced as soon as possible.
During operation, the teeth of the sprocket wheels acquire a polished or slightly worn band above the root circle. A slight polish is often produced on the inner side bars, in-spite of correctly aligned wheels. If there are signs of marked wear, however, its cause is to be investigated and chain closely inspected. Burrs on the edges of the teeth point to vibration of the chain. Sprocket wheels cause teeth sustained major deformation should be replaced as soon as possible. The bearings and bearing pins, there fastenings and their true and even running are to be checked at overhauls.
Admissible Wear of the Chains
The chain wear is directly proportional to the lengthening of the chain. The maximum admissible chain elongation is approximately 1% of the length of the chain. Also check relative position of camshaft w.r.t. crankshaft, the limiting maximum deviation allowed be 2 degree.
Reference and Images
“Marine Engineering Practice” by Vikram Gokhale and N. Nanda