| Wear rings or rubbing bands made of bronze alloy or steel or cast iron(in hfo engines). Their purpose are- they provide rubbing surfaces with low frictional characteristics & they prevent hot upper side wall of piston from making contact with liner working surface of liner. this is achieved by increasing the radial clearance between piston and liner. |
Since very small needle lift is obtained in the test equipment result in an unequal pressure distribution in the cut off shaft resulting in a hard contact in a small area along with high frequency oscillations, low lubricity of test oil will increase the chance of seizure. Full lift and high lubricity of heavy oil eliminates this risk of seizure during normal operation.( Always open and clean slide type valves before testing as cold sticky heavy oil along with small clearances can cause restriction in the movement of the spindle).
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