Valve tappet
The function of the tappet is to transmit the thrust of the cam to the push rod (or valve stem) and to withstand the lateral force exerted by the rotation of the camshaft. For the valve side-mounted valve mechanism, the tappet is generally made of a fungus type, and an adjusting screw is installed on the top of the tappet to adjust the valve clearance. The tappet of the valve-mounted valve train is generally made into a cylinder type to reduce weight. Shown is the roller-type hold, which has the advantage of reducing the lateral force on the tappet caused by friction. This tappet has a complex structure and a large weight. Generally used in large-bore diesel engines. Tappets are usually made of nickel-chromium alloy cast iron or chilled alloy cast iron. The friction surface should be finely ground after heat treatment.
The tappets of some engines are directly installed in the guide holes drilled at the corresponding positions on the cylinder block, and the tappets of some engines are installed in detachable tappet guide bodies.