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A pair of poppet valves bent by collision with a piston after timing belt failure. The engine was running at 4500 RPM. In interference engine designs, replacing a timing belt in regular intervals (manufacturers recommend intervals ranging from 60,000 to 104,000 miles) or repairing chain issues as soon as they are discovered is essential, as incorrect timing may result in the pistons and valves ...
The valves are typically operated by a camshaft rotating at half the speed of the crankshaft. It has a series of cams along its length, each designed to open a valve during the appropriate part of an intake or exhaust stroke. A tappet between valve and cam is a contact surface on which the cam slides to open the valve. Many engines use one or ...
With traditional fixed valve timing, an engine will have a period of "valve overlap" at the end of the exhaust stroke, when both the intake and exhaust valves are open. The intake valve is opened before the exhaust gases have completely left the cylinder, and their considerable velocity assists in drawing in the fresh charge. Engine designers ...
A possible downside to early intake valve closing is that it significantly lowers the temperature of the combustion chamber, which can increase hydrocarbon emissions. [3] Early intake valve opening Early intake valve opening is another variation that has significant potential to reduce emissions. In a traditional engine, a process called valve ...
Valve float is an adverse condition which can occur at high engine speeds [1] when the poppet valves in an internal combustion engine valvetrain do not properly follow the closure phase of the cam lobe profile. This reduces engine efficiency and performance.
The example locomotive is a simple, non-compound, type with two outside cylinders and valve gear, coupled driving wheels and a separate tender. Only basic balancing is covered with no mention of the effects of different cylinder arrangements, crank angles, etc. since balancing methods for three- and four-cylinder locomotives can be complicated ...
These Crossley Otto Scavenging Engines were made possible by the recent change from slide valves to poppet valves, which allowed more flexible control over valve timing events. [1] The closing of the exhaust valve occurred more than 30 degrees later than on earlier engines, giving a long 'overlap' period (when both the intake and exhaust valves ...
A stroke is the action of a piston travelling the full length of its cylinder.In a two-stroke engine, one of the two strokes combines primarily the intake stroke and the combustion stroke, while the other stroke primarily combines the compression stroke and the exhaust stroke, though technically since both ports are exposed during both the combustion and compression strokes, some reversion ...