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In spark-ignition internal combustion engines, knocking (also knock, detonation, spark knock, pinging or pinking) occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but when one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.
False brinelling of a bearing. False brinelling is a bearing damage caused by fretting, with or without corrosion, [1] that causes imprints that look similar to brinelling, but are caused by a different mechanism. False brinelling may occur in bearings which act under small oscillations [2] or vibrations. [3]
Torsional vibration is a concern in the crankshafts of internal combustion engines because it could break the crankshaft itself; shear-off the flywheel; or cause driven belts, gears and attached components to fail, especially when the frequency of the vibration matches the torsional resonant frequency of the crankshaft.
Engine balance refers to how the inertial forces produced by moving parts in an internal combustion engine or steam engine are neutralised with counterweights and balance shafts, to prevent unpleasant and potentially damaging vibration. The strongest inertial forces occur at crankshaft speed (first-order forces) and balance is mandatory, while ...
In most steam engine designs there is a short time at the end of the return stroke of the piston when all the valves are shut and it is compressing any remaining steam. Water can be introduced from the boiler or in a cold engine, steam will condense to water on the cool walls of the cylinders and can potentially hydrolock an engine.
Harmonic balancer lower pulley on a four-cylinder engine. A harmonic damper is a device fitted to the free (accessory drive) end of the crankshaft of an internal combustion engine to counter torsional and resonance vibrations from the crankshaft.
A rolling element bearing's static load rating is defined to avoid this failure type. Increasing the number of elements can provide better distribution of the load, so bearings intended for a large load may have many balls, or use needles instead. This decreases the chances of brinelling, but increases friction and other factors.
Headphones allow humans to listen to ultrasound as well. A high pitched 'buzzing sound' in bearings indicates flaws in the contact surfaces, and when partial blockages occur in high pressure fluids the orifice will cause a large amount of ultrasonic noise. Ultrasound is used in the Shock Pulse Method [19] of condition monitoring.