The task of the sleeves is to provide sealing in the engine together with the valves. It is to control the fuel entering the combustion chamber for the intake valves and the exit of the burning gases for the exhaust valves.
It is fixed to the cover like Gayd. There are also covers with direct bearing, ie not attached to the trunk. The guide and trunk axis of the valve must be compatible with each other. When the axis is misaligned or the valve angle is not fully centered, the sealing cannot be ensured and the engine loses power. Burning starts at the angles of the exhaust valves. Likewise, circularity should be appropriate at the angle of the bag. It should be mounted on the cover with suitable tightness. These directly affect the working performance of the valve.
Therefore, care should be taken to avoid these inconveniences during the end-of-assembly grinding of the boot. The most important task of the valve is to show wear resistance in the engine at high temperatures. Lugs made of high alloy and hardness are therefore made of steel or white cast iron.