The main parts of the valve train of the forklift:
Valve: The valve is divided into two types: the intake valve and the exhaust valve. Its function is to open and close the intake and exhaust passages. It consists of the head and the rod. The head is used to open and close the intake and exhaust passages, and the rod is used to guide the movement of the valve. The intake valve is made of ordinary alloy steel, and the exhaust valve is made of heat-resistant alloy steel because the exhaust valve head is directly in contact with the combustion gas and is seriously heated.
In order to ensure that the valve head and the valve seat are in close contact and heat conduction, a tapered joint surface is adopted between the valve head and the valve seat, and is ground. The angle between the cone and the top plane is called the valve cone angle, and the common valve cone angle is 30° and 45°. The valve shaft is the valve movement guide. A common valve stem has a groove at the end for mounting a tapered locking tab.
Valve seat: The valve seat is a circular seat hole directly machined on the cylinder (side-mounted valve) or cover (overhead valve), which cooperates with the valve to seal. Some valve seats can be machined into a seat ring with wear-resistant alloy cast iron, embedded in the cylinder block or cylinder head.
Valve guide: Its function is to guide the valve to make correct axial movement, and also transfer the heat of the valve stem to the water jacket indirectly. In order to facilitate repair and replacement, the valve guide is made separately and pressed into the cylinder block (or cylinder head). When the valve guide is pressed into the cylinder block (or cylinder head), there should be a certain amount of interference and penetration depth to ensure good heat transfer.
Valve spring: Its function is to ensure the tightness of the valve and the valve seat, and to slow down and overcome the inertial force generated by the valve and other transmission parts, so as to prevent the normal operation of the valve train.
Valve lifter: It transmits the push motion of the cam to the valve (side-mounted) or push rod (overhead) to control the opening and closing of the valve.
Valve push rod: In the overhead valve type valve train, the movement of the tappet is transmitted to the rocker arm. The push rod is a straight rod made of hollow steel tube, the ends are welded with different shapes of ends, the upper end is concave spherical, the ball head of the adjustment screw on the rocker arm is located therein; the lower end is a ball head for insertion The concave ball bearing of the rod.
Valve rocker arm: Its function is to transfer the movement of the tappet to the valve. It is a unequal length lever with a round hole in the middle. The end of the long arm has a circular arc working surface in contact with the valve tail; the end of the short arm has a screw hole for mounting the adjusting screw and the lock nut to adjust the valve clearance. The middle is a rocker bearing with a bronze bushing.
Rocker shaft: It is a hollow circular shaft. It is mounted on the cylinder head with several supports. The rocker arm is set on the rocker shaft and can swing on the shaft. The inner bore of the shaft communicates with the main oil passage to supply the lubricating oil of the valve train.
Camshaft: Used to control the closing time and opening degree of each cylinder valve. And drive oil pump, gasoline pump, distributor and other accessories. It is made up of an intake cam, an exhaust cam, a journal, a gear that drives the oil pump and the distributor, and an eccentric that pushes the rocker arm of the gasoline pump.
Timing Gear: A camshaft is typically driven by a crankshaft through a pair of timing gears. The pinion is mounted on the front end of the crankshaft and is called the crankshaft timing gear. The large gear is mounted on the front end of the camshaft and is called a camshaft timing gear. The ratio of the large and small gears is 2:1, that is, the crankshaft is rotated for two weeks, and the camshaft is rotated one revolution.
In order to ensure the correct valve phase and ignition timing, the corresponding positions of the two gears are engraved with the engagement mark. In order to limit the axial sway caused by the change of the camshaft during operation with the engine speed, an axial limiting device is provided in the installation.
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