Valve Action
Thursday, September 10, 2009
, Posted by Subru at 6:30 PM
There are usually two valves per cylinder.The valves are opened and closed by the action of the valve train.One of the simplest valve trains shown below.
It has a camshaft mounted on the top of the cylinder head.The camshaft is driven from crankshaft by a belt with teeth on its inside.The teeth match the teeth on the sprockets on the crankshaft and camshaft.
the camshaft has two cams for each cylinder,one for the intake valve and one for exhaust valve.The cam is a round collar with a high spot, or lobe.
The top of the valve stem is covered with a small hollow cylinder called a bucket valve tappet.It is called a bucket valve tappet because it is shaped like an upside-down bucket.When the camshaft and cam rotate,the lobe comes around and pushes the valve tappet and valve stem,down.The valve opens.When the lobe passes out from valve up so that the valve closes.
Engine with the camshaft on the cylinder head are called overhead-camshaft engines.They are more responsive than other type of valve train.This is because there are fewer parts in the valve tarin
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