Search results
Results from the WOW.Com Content Network
Overspeed is a condition in which an engine is allowed or forced to turn beyond its design limit. The consequences of running an engine too fast vary by engine type and model and depend upon several factors, the most important of which are the duration of the overspeed and the speed attained.
Dieseling or engine run-on is a condition that can occur in spark-plug-ignited, gasoline-powered internal combustion engines, whereby the engine keeps running for a short period after being turned off, drawing fuel through the carburetor, into the engine and igniting it without a spark.
Diesel engine runaway is an occurrence in diesel engines, in which the engine draws excessive fuel from an unintended source and overspeeds at higher RPMs, producing up to ten times the engine's rated output resulting in a catastrophic mechanical failure due to a lack of lubrication. [1]
The reduced engine speeds allow more time for autoignition chemistry to complete thus promoting the possibility of pre-ignition and so called "mega-knock". Under these circumstances, there is still significant debate as to the sources of the pre-ignition event. [3] Pre-ignition and engine knock both sharply increase combustion chamber temperatures.
Pressure in cylinder pattern in dependence on ignition timing: (a) - misfire, (b) too soon, (c) optimal, (d) too late. In a spark ignition internal combustion engine, ignition timing is the timing, relative to the current piston position and crankshaft angle, of the release of a spark in the combustion chamber near the end of the compression stroke.
The principal conditions are decompression illness (which covers decompression sickness and arterial gas embolism), nitrogen narcosis, high pressure nervous syndrome, oxygen toxicity, and pulmonary barotrauma (burst lung). Although some of these may occur in other settings, they are of particular concern during diving activities.
At idle speeds on a new engine poor machining tolerances could prevent the lifter from spinning and destroy the camshaft. After 20 minutes of wear, or "self machining" at higher engine speeds they would typically be able to spin freely. In the past, the engine break-in period was very important to the overall life and durability of the engine.
Narcosis results from breathing gases under elevated pressure, and may be classified by the principal gas involved. The noble gases, except helium and probably neon, [2] as well as nitrogen, oxygen and hydrogen cause a decrement in mental function, but their effect on psychomotor function (processes affecting the coordination of sensory or cognitive processes and motor activity) varies widely.